Via Earthsky.org: The origin of the term is religious, at least according to Christian pastor John Hagee, who wrote a 2013 book about Blood Moons.
Meanwhile, both astronomers and some proponents of Christian prophesy are talking about the upcoming lunar tetrad – the series of four total lunar eclipses – beginning on the night of April 14-15.
Total eclipse of October 27, 2004 via Fred Espenak of NASA
Other times in astronomy you hear “moon” and “blood” in same sentence. The full moon nearly always appears coppery red during a total lunar eclipse. That’s because the dispersed light from all the Earth’s sunrises and sunsets falls on the face of the moon at mid-eclipse. Thus the termblood moon can be and probably is applied to any and all total lunar eclipses. It’s only in years where volcanic activity is pronounced that the moon’s face during a total lunar eclipse might appear more brownish or gray in color. Usually, the moon looks red. We astronomy writers often say it looks blood red. Why? Because it sounds dramatic, and a lunar eclipse is a dramatic natural event. Read more here: Why does the moon look red during a total lunar eclipse?
The Hunter’s Moon, in skylore, is also sometimes called the Blood Moon. Why? Probably because it’s a characteristic of these autumn full moons that they appear nearly full – and rise soon after sunset – for several evenings in a row. Many people see them when they are low in the sky, shortly after they’ve risen, at which time there’s more atmosphere between you and the moon than when the moon is overhead. When you see the moon low in the sky, the extra air between you and the moon makes the moon look reddish. Voila. Blood moon.
The second total lunar eclipse of the coming lunar tetrad will take place on October 8, the same night as the Hunter’s Moon. So there will be two reasons to use the term Blood Moon that night.
Dates for the Northern Hemisphere’s Harvest and Hunter’s Moons in 2014 and 2015:
Harvest Moon: September 9
Autumn Equinox: September 23
Hunter’s (Blood) Moon: October 8
Autumn Equinox: September 23
Harvest Moon: September 28
Hunter’s (Blood) Moon: October 27
Bottom line: The term Blood Moon in Biblical prophecy appears to have been popularized by two Christian pastors, Mark Blitz and John Hagee. They use the term Blood Moon to apply to the full moons of the upcoming tetrad – four successive total lunar eclipses, with no partial lunar eclipses in between, each of which is separated from the other by six lunar months (six full moons) – beginning on the night of April 14-15, 2014.
The moon took on an eerie blood-red hue early Tuesday during the first total lunar eclipse of 2014, a celestial sight that wowed potentially millions of stargazers across North and South America.
The total lunar eclipse of April 15 lasted about 3.5 hours between late Monday and early Tuesday, with the Earth’s shadow slowing darkening the face of the so-called “Blood Moon” in a jaw-dropping sight for stargazers willing to stay up extra late or rise super-early for the event.
Photographer Sean Parker of Tucson, Ariz., created this mosaic of the total lunar eclipse phases on April 15, 2014 using images taken with a through a 12″ LX Meade 200 telescope with a Canon 6D camera.
The lunar eclipse peaked at 3 a.m. EDT (0700 GMT), with the moon taking 78 minutes to pass through the darkest point of Earth’s shadow. It was visible from most of North and South America, Hawaii and parts of Alaska. The eclipse was the first of four consecutive total lunar eclipses, known as a “tetrad,” between April 2014 and September 2015.
Astronomer Bob Berman, who hosted a live lunar eclipse webcast for the Slooh community telescope using views from Arizona’s Prescott Observatory, said event was also one for the record books because of another bright object in the predawn sky.
“It was the most special one, I would say, of our lives,” Berman said during the Slooh webcast. “What made it particularly extraordinary was that it happened on the same night as the closest approach of Mars to Earth in years.”
Mars made its closest approach to Earth since 2008 on Monday night (April 14), coming within 57.4 million miles (92.4 million km) of our planet.
So the Red Planet and the “Blood Moon” shined together in the predawn sky in a rare event, Berman said, adding that the bright blue star Spica completed the show.
Millions of people were greeted last night with a strange celestial sighting, the “blood moon” lunar eclipse. The phenomenon occurs when the moon passes into the earth’s shadow and, for about an hour, takes on a reddish hue from the sunlight being refracted around the earth’s horizon.
Due to cloud cover over much of North America, many people, particularly on the east coast, didn’t get a chance to see the blood moon Tuesday morning. Don’t worry though, we’ve got a time lapse of the event for you right here.
Year New Moon First Quarter Full Moon Last Quarter
2014 Jan 1 11:14 Jan 8 03:39 Jan 16 04:52 Jan 24 05:19
Jan 30 21:39 Feb 6 19:22 Feb 14 23:53 Feb 22 17:15
Mar 1 08:00 Mar 8 13:27 Mar 16 17:09 Mar 24 01:46
Mar 30 18:45 Apr 7 08:31 Apr 15 07:42 t Apr 22 07:52
Apr 29 06:14 A May 7 03:15 May 14 19:16 May 21 12:59
May 28 18:40 Jun 5 20:39 Jun 13 04:11 Jun 19 18:39
Jun 27 08:09 Jul 5 11:59 Jul 12 11:25 Jul 19 02:08
Jul 26 22:42 Aug 4 00:50 Aug 10 18:09 Aug 17 12:26
Aug 25 14:13 Sep 2 11:11 Sep 9 01:38 Sep 16 02:05
Sep 24 06:14 Oct 1 19:33 Oct 8 10:51 t Oct 15 19:12
Oct 23 21:57 P Oct 31 02:48 Nov 6 22:23 Nov 14 15:16
Nov 22 12:32 Nov 29 10:06 Dec 6 12:27 Dec 14 12:51
Dec 22 01:36 Dec 28 18:31
In 2014, there are two solar eclipses and two total lunar eclipses as follows.
Predictions for the eclipses are summarized in Figures 1, 2, 3, and 4. World maps show the regions of visibility for each eclipse. The lunar eclipse diagrams also include the path of the Moon through Earth’s shadows. Contact times for each principal phase are tabulated along with the magnitudes and geocentric coordinates of the Sun and Moon at greatest eclipse.
All times and dates used in this publication are in Universal Time or UT. This astronomically derived time system is colloquially referred to as Greenwich Mean Time or GMT. To learn more about UT and how to convert UT to your own local time, see Time Zones and Universal Time.
The first eclipse of the year is well placed for observers throughout the Western Hemisphere. The eclipse occurs at the lunar orbit’s ascending node in Virgo. The apparent diameter of the Moon is close to its average since the eclipse occurs nearly midway between apogee (April 08 at 14:53 UT) and perigee (April 23 at 00:28 UT). This is the first of four consecutive total lunar eclipses in 2014 and 2015 (see Lunar Eclipse Tetrads).
The Moon’s orbital trajectory takes it through the southern half of Earth’s umbral shadow. Although the eclipse is not central, the total phase still lasts 78 minutes. The Moon’s path through Earth’s shadows as well as a map illustrating worldwide visibility of the event are shown in Figure 1. The times of the major eclipse phases are listed below.
Penumbral Eclipse Begins: 04:53:37 UT
Partial Eclipse Begins: 05:58:19 UT
Total Eclipse Begins: 07:06:47 UT
Greatest Eclipse: 07:45:40 UT
Total Eclipse Ends: 08:24:35 UT
Partial Eclipse Ends: 09:33:04 UT
Penumbral Eclipse Ends: 10:37:37 UT
At the instant of greatest eclipse (07:45:40 UT) the Moon lies at the zenith for a point in the South Pacific about 3000 km southwest of the Galapagos Islands. The umbral eclipse magnitude peaks at 1.2907 as the Moon’s northern limb passes 1.7 arc-minutes south of the shadow’s central axis. In contrast, the Moon’s southern limb lies 9.0 arc-minutes from the southern edge of the umbra and 40.0 arc-minutes from the shadow centre. Thus, the northern half of the Moon will appear much darker than the southern half because it lies deeper in the umbra. Since the Moon samples a large range of umbral depths during totality, its appearance will change significantly with time. It is not possible to predict the exact brightness distribution in the umbra, so observers are encouraged to estimate the Danjon value at different times during totality (see Danjon Scale of Lunar Eclipse Brightness). Note that it may also be necessary to assign different Danjon values to different portions of the Moon (i.e., north verses south).
During totality, the spring constellations are well placed for viewing so a number of bright stars can be used for magnitude comparisons. Spica (m = +1.05) is the most conspicuous star lying just 2° west of the eclipsed Moon. This juxtaposition reminds the author of the total lunar eclipse of 1968 Apr 13 when Spica appeared only 1.3° southwest of the Moon at mid-totality. The brilliant blue color of Spica made for a striking contrast with the crimson Moon. Just a week past opposition, Mars (m = -1.4) appears two magnitudes brighter than Spica and lies 9.5° northwest of the Moon. Arcturus (m = +0.15) is 32° to the north, Saturn (m = +0.2) is 26° to the east, and Antares (m = +1.07) is 44° to the southeast.
The entire event is visible from both North and South America. Observers in the western Pacific miss the first half of the eclipse because it occurs before moonrise. Likewise most of Europe and Africa experience moonset just as the eclipse begins. None of the eclipse is visible from north/east Europe, eastern Africa, the Middle East or Central Asia.
Table 1 lists predicted umbral immersion and emersion times for 25 well-defined lunar craters. The timing of craters is useful in determining the atmospheric enlargement of Earth’s shadow (see Crater Timings During Lunar Eclipses).
The April 15 eclipse is the 56th eclipse of Saros 122. This series began on 1022 August 14 and is composed of 74 lunar eclipses in the following sequence: 22 penumbral, 8 partial, 28 total, 7 partial, and 9 penumbral eclipses (Espenak and Meeus, 2009). The last eclipse of the series is on 2338 October 29. Complete details for Saros 122 can be found at:
The first solar eclipse of 2014 occurs at the Moon’s descending node in southern Aries. This particular eclipse is rather unusual because the central axis of the Moon’s antumbral shadow misses Earth entirely while the shadow edge grazes the planet. Classified as a non-central annular eclipse, such events are rare. Out of the 3,956 annular eclipses occurring during the 5,000-year period -2000 to +3000, only 68 of them or 1.7% are non-central (Espenak and Meeus, 2006).
The northern edge of the antumbral shadow first touches down in Antarctica at 05:57:35 UT. The instant of greatest eclipse occurs just six minutes later at 06:03:25 UT. For an observer at the geographic coordinates nearest the shadow axis (131° 15.6′ E, 79° 38.7′ S), the Sun would appear on the horizon during the 49-second annular phase. Six minutes later (06:09:36 UT), the antumbral shadow lifts off the surface of Earth as the annular eclipse ends. The entire zone of annularity appears as a small D-shaped region in eastern Antarctica (Figure 2).
A partial eclipse is seen within the much broader path of the Moon’s penumbral shadow, that includes the southern Indian Ocean, the southern edge of Indonesia and all of Australia (Figure 2). Local circumstances for a number of cities in Australia are found inTable 2. All times are given in Universal Time. The Sun’s altitude and azimuth, the eclipse magnitude and obscuration are all given at the instant of maximum eclipse.
This is the 21st eclipse of Saros 148 (Espenak and Meeus, 2006). The family began with a series of 20 partial eclipses starting on 1653 Sep 21. The 2014 Apr 29 eclipse is actually the first annular eclipse of the series. It will be followed by another annular on 2032 May 09. The series switches to hybrid on 2050 May 20 followed by the first 40 total eclipses on 2068 May 31. After a final 12 partial eclipses, Saros 148 terminates on 2987 Dec 12. Complete details for the 75 eclipses in the series (in the sequence of 20 partial, 2 annular, 1 hybrid, 40 total, and 12 partial) may be found at:
The second lunar eclipse of 2014 is also total and is best seen from the Pacific Ocean and bordering regions. The eclipse occurs at the Moon’s descending node in southern Pisces, two days after perigee (October 06 at 09:41 UT). This means that the Moon will appear 5.3% larger than it did during the April 15 eclipse (32.7 vs. 31.3 arc-minutes).
This time the orbital path of the Moon takes it through the northern half of Earth’s umbral shadow. The total phase lasts 59 minutes primarily because the diameter of the umbral shadow is larger (1.49° verses 1.39°). The lunar path through Earth’s shadows as well as a map illustrating worldwide visibility of the event are shown in Figure 3. The times of the major eclipse phases are listed below.
Penumbral Eclipse Begins: 08:15:33 UT
Partial Eclipse Begins: 09:14:48 UT
Total Eclipse Begins: 10:25:10 UT
Greatest Eclipse: 10:54:36 UT
Total Eclipse Ends: 11:24:00 UT
Partial Eclipse Ends: 12:34:21 UT
Penumbral Eclipse Ends: 13:33:43 UT
At the instant of greatest eclipse (10:54:36 UT) the Moon lies near the zenith from a location in the Pacific Ocean about 2000 km southwest of Hawaii. At this time, the umbral magnitude peaks at 1.1659 as the Moon’s southern limb passes 6.6 arc-minutes north of the shadow’s central axis. In contrast, the Moon’s northern limb lies 5.4 arc-minutes from the northern edge of the umbra and 39.3 arc-minutes from the shadow centre. As a result, the southern half of the Moon will appear much darker than the northern half because it lies deeper in the umbra. The Moon samples a large range of umbral depths during totality so its appearance will change considerably with time. The exact brightness distribution in the umbra is difficult to predict, so observers are encouraged to estimate the Danjon value at different times during totality (see Danjon Scale of Lunar Eclipse Brightness). It may also be necessary to assign different Danjon values to different portions of the Moon (e.g., north vs. south).
During totality, the autumn constellations are well placed for viewing and the brighter stars can be used for magnitude comparisons. The center of the Great Square of Pegasus lies 15° to the northwest, its brightest star being Alpheratz (m = +2.02). Deneb Kaitos (m = +2.04) in Cetus is 30° south of the eclipsed Moon, while Hamal (m = +2.01) is 25° to the northeast, Aldebaran (m = +0.87) is 56° to the east, and Almach (m = +2.17) is 40° to the north.
Although relatively faint, the planet Uranus (m = +5.7) lies just 2/3° southeast of the Moon during totality. Is a transit of the Earth and Moon across the Sun’s disk visible from Uranus during the eclipse? An interesting idea but calculations show a miss. From Uranus, the Sun’s disk is only 1.7 arc-minutes in diameter and this is a very small target to hit. Nevertheless, transits of Earth from Uranus are possible – the next one takes place on 2024 November 17 (Meeus, 1989).
The entire October 08 eclipse is visible from the Pacific Ocean and regions immediately bordering it. The northwestern 1/3 of North America also witnesses all stages. Farther east, various phases occur after moonset. For instance, the Moon sets during totality from eastern Canada and the USA. Observers in South America also experience moonset during the early stages of the eclipse. All phases are visible from New Zealand and eastern 1/4 of Australia – the Moon rises during the early partial phases from Australia’s west coast. Most of Japan and easternmost Asia catch the entire eclipse as well. Farther west in Asia, various stages of the eclipse occur before moonrise. None of the eclipse is visible from Europe, Africa, and the Middle East.
Table 3 lists predicted umbral immersion and emersion times for 25 well-defined lunar craters. The timing of craters is useful in determining the atmospheric enlargement of Earth’s shadow (see Crater Timings During Lunar Eclipses).
The October 08 eclipse is the 42nd eclipse of Saros 127. This series is composed of 72 lunar eclipses in the following sequence: 11 penumbral, 18 partial, 16 total, 20 partial, and 7 penumbral eclipses (Espenak and Meeus, 2009). The family began with the penumbral eclipse of 1275 July 09, and ends with another penumbral eclipse on 2555 September 02. Complete details for Saros 127 can be found at:
The final event of 2014 occurs at the Moon’s ascending node in southern Virgo. Although it is only a partial solar eclipse, it is of particular interest because the event is widely visible from Canada and the USA (Figure 4).
The penumbral shadow first touches Earth’s surface near the Kamchatka Peninsula in eastern Siberia at 19:37:33 UT. As the shadow travels east, much of North America will be treated to a partial eclipse. The eclipse magnitude from cities like Vancouver (0.658), San Francisco (0.504), Denver (0.556), and Toronto (0.443) will surely attract the media’s attention.
Greatest eclipse occurs at 21:44:31 UT in Canada’s Nunavut Territory near Prince of Wales Island where the eclipse in the horizon will have a magnitude of 0.811. At that time, the axis of the Moon’s shadow will pass about 675 km above Earth’s surface. A sunset eclipse will be visible from the eastern half of the USA and Canada (except for the far northeast). The partial eclipse ends when the penumbra leaves Earth at 23:51:40 UT.
Local circumstances and eclipse times for a number of cities in Canada and Mexico are listed in Table 4, and for the USA in Table 5. All times are in Local Daylight Time. The Sun’s altitude and azimuth, the eclipse magnitude and eclipse obscuration are all given at the instant of maximum eclipse. When the eclipse is in progress at sunset, this information is indicated by ‘- s’.
This is the 9th eclipse of Saros 153 (Espenak and Meeus, 2006). The series began on 1870 Jul 28 with a string of 13 partial eclipses. The first of 49 annular eclipses begins on 2104 Dec 17. The series ends with a set of 8 partial eclipses the last of which occurs on 3114 Aug 22. In all, Saros 153 produces 70 solar eclipses in the sequence of 13 partial, 49 annular, and 8 partial eclipses. Complete details for the series can be found at:
The lunar eclipses of 2014 are the first of four consecutive total lunar eclipses – a series known as a tetrad. During the 5000-year period from -1999 to +3000, there are 4378 penumbral eclipses (36.3%), 4207 partial lunar eclipses (34.9%) and 3479 total lunar eclipses (28.8%). Approximately 16.3% (568) of all total eclipses belong to one of the 142 tetrads occurring over this period (Espenak and Meeus, 2009). The mechanism causing tetrads involves the eccentricity of Earth’s orbit in conjunction with the timing of eclipse seasons (Meeus, 2004). During the present millennium, the first eclipse of every tetrad occurs sometime from February to July. In later millennia, the first eclipse date gradually falls later in the year because of precession.
Italian astronomer Giovanni Schiaparelli first pointed out that the frequency of tetrads is variable over time. He noticed that tetrads were relatively plentiful during one 300-year interval, while none occurred during the next 300 years. For example, there are no tetrads from 1582 to 1908, but 17 tetrads occur during the following 2 and 1/2 centuries from 1909 to 2156. The ~565-year period of the tetrad “seasons” is tied to the slowly decreasing eccentricity of Earth’s orbit. Consequently, the tetrad period is gradually decreasing (Meeus, 2004). In the distant future when Earth’s eccentricity is 0, tetrads will no longer be possible.
The umbral magnitudes of the total eclipses making up a tetrad are all relatively small. For the 300-year period 1901 to 2200, the largest umbral magnitude of a tetrad eclipse is 1.4251 on 1949 Apr 13. For comparison, some other total eclipses during this period are much deeper. Two examples are the total eclipses of 2000 Jul 16 and 2029 Jun 26 with umbral magnitudes of 1.7684 and 1.8436, respectively.
Table 6 gives the dates of each eclipse in the 8 tetrads occurring during the 21st century. The tetrad prior to 2014-15 was in 2003-04 while the next group is nearly 20 years later in 2032-33.
The altitude a and azimuth A of the Sun or Moon during an eclipse depend on the time and the observer’s geographic coordinates. They are calculated as follows:
h = 15 (GST + UT - α ) + λ
a = arcsin [sin δ sin φ + cos δ cos h cos φ]
A = arctan [-(cos δ sin h)/(sin δ cos φ - cos δ cos h sin φ)]
h = hour angle of Sun or Moon
a = altitude
A = azimuth
GST = Greenwich Sidereal Time at 0:00 UT
UT = Universal Time
α = right ascension of Sun or Moon
δ = declination of Sun or Moon
λ = observer's longitude (east +, west -)
φ = observer's latitude (north +, south -)
During the eclipses of 2014, the values for GST and the geocentric Right Ascension and Declination of the Sun or the Moon (at greatest eclipse) are as follows:
Eclipse Date GST α δ
Total Lunar 2014 Apr 15 13.560 13.556 -10.050
Annular Solar 2014 Apr 29 14.475 2.431 14.448
Total Lunar 2014 Oct 08 1.133 0.919 6.307
Partial Solar 2014 Oct 23 2.148 13.887 -11.613
Van Allen Probes Find Storage Ring in Earth’s Outer Radiation Belt
Since their discovery over 50 years ago, the Earth’s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. Observations from NASA’s Van Allen Probes reveal an isolated third ring in the outer radiation belt.
A cutaway model of the radiation belts with the 2 RBSP satellites flying through them. The radiation belts are two donut-shaped regions encircling Earth, where high-energy particles, mostly electrons and ions, are trapped by Earth’s magnetic field. This radiation is a kind of “weather” in space, analogous to weather on Earth, and can affect the performance and reliability of our technologies, and pose a threat to astronauts and spacecraft.
The inner belt extends from about 1000 to 8000 miles above Earth’s equator. The outer belt extends from about 12,000 to 25,000 miles. This graphic also shows other satellites near the region of trapped radiation.
NASA’s Van Allen Probes Discover a Surprise Circling Earth
After most NASA science spacecraft launches, researchers wait patiently for months as instruments on board are turned on one at a time, slowly ramped up to full power, and tested to make sure they work at full capacity. It’s a rite of passage for any new satellite in space, and such a schedule was in place for the Van Allen Probes when they launched on Aug. 30, 2012, to study two giant belts of radiation that surround Earth.
But a group of scientists on the mission made a case for changing the plan. They asked that the Relativistic Electron Proton Telescope (REPT) be turned on early – just three days after launch — in order that its observations would overlap with another mission called SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer), that was soon going to de-orbit and re-enter Earth’s atmosphere.
It was a lucky decision. Shortly before REPT turned on, solar activity on the sun had sent energy toward Earth that caused the radiation belts to swell. The REPT instrument worked well from the moment it was turned on Sep. 1. It made observations of these new particles trapped in the belts, recording their high energies, and the belts’ increased size.
Then something happened no one had ever seen before: the particles settled into a new configuration, showing an extra, third belt extending out into space. Within mere days of launch, the Van Allen Probes showed scientists something that would require rewriting textbooks.
“By the fifth day REPT was on, we could plot out our observations and watch the formation of a third radiation belt,” says Shri Kanekal, the deputy mission scientist for the Van Allen Probes at NASA’s Goddard Space Flight Center in Greenbelt, Md. and a co-author of a paper on these results. “We started wondering if there was something wrong with our instruments. We checked everything, but there was nothing wrong with them. The third belt persisted beautifully, day after day, week after week, for four weeks.”
The scientists published their results in a paper in the journal Science on Feb. 28, 2013. Incorporating this new configuration into their models of the radiation belts offers scientists new clues to what causes the changing shapes of the belts – a region that can sometimes swell dramatically in response to incoming energy from the sun, impacting satellites and spacecraft or pose potential threats to manned space flight.
Since their discovery over 50 years ago, the Earth’s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. Observations from NASA’s Van Allen Probes reveal an isolated third ring in the outer radiation belt.
The radiation belts, or Van Allen belts, were discovered with the very first launches of satellites in 1958 by James Van Allen. Subsequent missions have observed parts of the belts – including SAMPEX, which observed the belts from below – but what causes such dynamic variation in the belts has remained something of a mystery. Indeed, seemingly similar storms from the sun have at times caused completely different effects in the belts, or have sometimes led to no change at all.
The Van Allen Probes consist of two identical spacecraft with a mission to map out this region with exquisite detail, cataloging a wide range of energies and particles, and tracking the zoo of magnetic waves that pulse through the area, sometimes kicking particles up to such frenzied speeds that they escape the belts altogether.
Published on 28 Feb 2013
A new radiation belt and storage ring has been discovered above Earth; It is shown here using actual data as the middle arc of orange and red of the three arcs seen on each side of the Earth. The new belt was observed for the first time by Relativistic Electron-Proton Telescopes (REPT) flying on NASA’s twin Van Allen Probes, which launched on Aug. 30 2012. CREDIT: JHUAPL/LASP
“We’ve had a long run of data from missions like SAMPEX,” says Daniel Baker, who is the principal investigator for REPT at the University of Colorado in Boulder and first author on the Science paper. “But we’ve never been in the very throat of the accelerator operating a few hundred miles above our head, speeding these particles up to incredible velocities.”
In its first six months in orbit, the instruments on the Van Allen Probes have worked exceptionally well and scientists are excited about a flood of observations coming in with unprecedented clarity. This is the first time scientists have been able to gather such a complete set of data about the belts, with the added bonus of watching from two separate spacecraft that can better show how events sweep across the area.
Spotting something new in space such as the third radiation belt has more implications than the simple knowledge that a third belt is possible. In a region of space that remains so mysterious, any observations that link certain causes to certain effects adds another piece of information to the puzzle.
Baker likes to compare the radiation belts to the particle storage rings in a particle physics accelerator. In accelerators, magnetic fields are used to hold the particles orbiting in a circle, while energy waves are used to buffet the particles up to ever faster speeds. In such accelerators, everything must be carefully tuned to the size and shape of that ring, and the characteristics of those particles. The Van Allen Belts depend on similar fine-tuning. Given that scientists see the rings only in certain places and at certain times, they can narrow down just which particles and waves must be causing that geometry. Every new set of observations helps narrow the field even further.
“We can offer these new observations to the theorists who model what’s going on in the belts,” says Kanekal. “Nature presents us with this event – it’s there, it’s a fact, you can’t argue with it — and now we have to explain why it’s the case. Why did the third belt persist for four weeks? Why does it change? All of this information teaches us more about space.”
› View larger
On Aug. 31, 2012, a giant prominence on the sun erupted, sending out particles and a shock wave that traveled near Earth. This event may have been one of the causes of a third radiation belt that appeared around Earth a few days later, a phenomenon that was observed for the very first time by the newly-launched Van Allen Probes. This image of the prominence before it erupted was captured by NASA’s Solar Dynamics Observatory (SDO). Credit:NASA/SDO/AIA/Goddard Space Flight Center
Scientists already have theories about just what kind of waves sweep out particles in the “slot” region between the first two belts. Now they must devise models to find which waves have the right characteristics to sweep out particles in the new slot region as well. Another tantalizing observation to explore lies in tracking the causes of the slot region back even further: on Aug. 31, 2012, a long filament of solar material that had been hovering in the sun’s atmosphere erupted out into space. Baker says that this might have caused the shock wave that led to the formation of the third ring a few days later. In addition, the new belt was virtually annihilated four weeks after it appeared by another powerful interplanetary shock wave from the sun. Being able to watch such an event in action provides even more material for theories about the Van Allen belts.
Despite the 55 years since the radiation belts were first discovered, there is much left to investigate and explain, and within just a few days of launch the Van Allen Probes showed that the belts are still capable of surprises.
“I consider ourselves very fortunate,” says Baker. “By turning on our instruments when we did, taking great pride in our engineers and having confidence that the instruments would work immediately and having the cooperation of the sun to drive the system the way it did – it was an extraordinary opportunity. It validates the importance of this mission and how important it is to revisit the Van Allen Belts with new eyes.”
The Johns Hopkins University Applied Physics Laboratory (APL) built and operates the twin Van Allen Probes. The Van Allen Probes comprise the second mission in NASA’s Living With a Star (LWS) program to explore aspects of the connected sun-Earth system that directly affect life and society. The program is managed by NASA Goddard.
A playlist of 4 Video’s on the Radiation Belt Storm Probe (RBSP) mission will explore Earth’s Van Allen Radiation Belts. The protons, ions, and electrons in these belts can be hazardous to both spacecraft and astronauts.
Published on 28 Sep 2012
the twin Radiation Belt Storm Probes (RBSP) have recorded the “music” of the Van Allen Radiation Belts -actually radio waves at acoustic frequencies. These frequencies may play a role in speeding up electrons in the belts. Video From you tube user ‘Coconut Science Lab’ his website: Jungle Joel
Van Allen Probes Find Storage Ring in Earth’s Outer Radiation Belt
NASA’s Living With a Star (LWS) program is a space-weather focused and applications driven research program. Its goal is to develop the scientific understanding necessary to effectively address those aspects of the connected sun–Earth system that directly affect life and society. The program is implemented by a series of inter-related science missions, space environment testbeds, and a targeted theory, modeling, and data analysis program. The Van Allen Probes are the second mission in the LWS program.Credit: NASA
This two part movie shows an Aug. 31 coronal mass ejection (CME) from the sun , the same event that caused depletion and refilling of the radiation belts just after the Relativistic Electron-Proton Telescope (REPT) instruments on the Van Allen Probes were turned on. The first movie shows the CME as captured by NASA’s Solar Dynamics Observatory (SDO); the second shows several views of the same CME from the Solar and Heliospheric Observatory (SOHO).
This graph shows energetic electron data gathered by the Relativistic Electron-Proton Telescope (REPT) instruments, on the twin Van Allen Probes satellites in eccentric orbits around the Earth, from Sept. 1, 2012 to Oct. 4, 2012 (horizontal axis). It shows three discrete energy channels (measured in megaelectron volts, or MeV). The third belt region (in yellow) and second slot (in green) are highlighted, and exist up until a coronal mass ejection (CME) destroys them on Oct. 1. The vertical axis in each is L*, effectively the distance in Earth radii at which a magnetic field line crosses the magnetic equatorial plane.Credit: LASP
One of the two Relativistic Electron-Proton Telescope (REPT) instruments for the Van Allen Probes is shown prior to and then during integration into the spacecraft in 2012. Each Van Allen Probe carries an identical suite of five instruments; REPT is part of the Energetic Particle, Composition, and Thermal Plasma Suite (ECT) aboard the Van Allen Probes.Credit: JHUAPL
Duration: 18.6 seconds
Available formats: 1280×720 MPEG-4 5 MB 320×180 PNG 229 KB 160×80 PNG 63 KB 80×40 PNG 17 KB How to play NASA’s movies
This long-term plot (approximately 12 years) from NASA’s Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) spacecraft shows the established two-belt structure of the Van Allen radiation belts above the Earth. The L value is distance above the Earth. New, more advanced instrumentation on the Van Allen Probes has revealed a third belt.
This animation shows meridional (from north-south) plane projections of the REPT-A and REPT-B electron flux values. The animation first shows the expected two-belt Van Allen zone structure; from Sept. 3 through Sept. 6 only an intense belt of electrons remains and the inner zone and traditional slot region have not changed; next, the third ‘storage ring’ belt feature persists while a new slot region is seen and a completely new outer zone population has formed. Then, around Oct. 1, the storage ring feature remains while the outer zone decays away.Credit: LASP
Duration: 30.2 seconds
Available formats: 1280×720 MPEG-4 6 MB 320×180 PNG 122 KB 160×80 PNG 34 KB 80×40 PNG 10 KB
This visualization, created using actual data from the Relativistic Electron-Proton Telescopes (REPT) on NASA’s Van Allen Probes, clearly shows the emergence of new third belt and second slot regions. The new belt is seen as the middle orange and red arc of the three seen on each side of the Earth. The twin Van Allen Probes launched on Aug. 30 2012.Credit: JHU/APL, from REPT data/LASP
Duration: 1.1 minutes
Available formats: 1280×720 MPEG-4 20 MB 320×180 PNG 159 KB 160×80 PNG 50 KB 80×40 PNG 16 KB
Radiation regions like the belts are found throughout our solar system and the universe. We are fortunate that we have this region of interest just a few thousand kilometers above the planet – it is like having our very own particle accelerator in the backyard. Here are four objects with radiation regions: The sun, Earth, Jupiter, and the Crab Nebula.Credit: NASA/JHUAPL
This Sept. 28 coronal mass ejection (CME) from the sun, captured by NASA’s Solar Dynamics Observatory (SDO), is the event which caused the near total annihilation of the new radiation belt and slot region on Oct. 1.Credit: NASA
Duration: 10.3 seconds
Available formats: 1000×1034 QT 8 MB 320×330 PNG 511 KB 160×80 PNG 67 KB 80×40 PNG 17 KB
This movie shows NASA’s Earth-orbiting heliophysics fleet as of 2013, from near Earth orbit out to the orbit of the moon. These missions study the thermosphere, ionosphere, and mesosphere; geospace and the magnetosphere; the heliosphere; and take solar observations and imagery. The Van Allen Probes (marked here as RBSP-A and RBSP-B) are in a highly elliptical orbit, shown in blue, around the Earth. Working as a team, these spacecraft provide the most comprehensive picture ever provided of how our sun interacts with our world.Credit: NASA
The Forecast Office of NOAA’s Space Weather Prediction Center is the nation’s official source of alerts, warnings, and watches. The office, staffed 24/7, is always vigilant for solar activity that can affect critical infrastructure.
The Space Weather Prediction Center has offered an email subscription service to customers both nationally and internationally since 2005. Now numbering over 32,000 subscribers, the satellite community accounts for about 9,500. Credit:NOAA.
Satellite industry revenues globally have grown at about nine percent on average since 2006. In 2011, the last year for which data are available, the revenue was more than $177B (USD).Credit: Satellite Industry Association.
Available formats: 864 x 648 JPEG 295 KB 320 x 240 PNG 257 KB 160 x 80 PNG 55 KB 80 x 40 PNG 27 KB
Satellite anomalies of various types are the result of high levels of charged particles. The Van Allen Probes offer unique measurements of these populations for the benefit of satellite builders and operators.Credit: JHUAPL
The presence of the Moon moderates Earth’s wobble on its axis, leading to a relatively stable climate over billions of years. From Earth, we always see the same face of the Moon because the Moon rotates once on its own axis in the same time that it travels once around Earth (called synchronous rotation).
The light areas of the Moon are known as the highlands. The dark features, called maria (Latin for seas), are impact basins that were filled with lava between 4 and 2.5 billion years ago.
Though the Moon has no internally generated magnetic field, areas of magnetism are preserved in the lunar crust, but how this occurred is a mystery. The early Moon appears not to have had the right conditions to develop an internal dynamo, the mechanism for global magnetic fields for the terrestrial planets.
How did the Moon come to be? The leading theory is that a Mars-sized body collided with Earth approximately 4.5 billion years ago, and the resulting debris from both Earth and the impactor accumulated to form our natural satellite. The newly formed Moon was in a molten state. Within about 100 million years, most of the global “magma ocean” had crystallized, with less dense rocks floating upward and eventually forming the lunar crust.
2013 Phases of the Moon
NOTE: All times are Universal time (UTC); to convert to local time add or subtract the difference between your time zone and UTC, remembering to include any additional offset due to summer time for dates when it is in effect.
A waxing crescent moon 17 jan 2013
Perigee and Apogee Dates and Times
a:For each perigee and apogee the distance in kilometres between the centres of the Earth and Moon is given. Perigee and apogee distances are usually accurate to within a few kilometres compared to values calculated with the definitive ELP 2000-82 theory of the lunar orbit; the maximum error over the years 1977 through 2022 is 12km in perigee distance and 6km at apogee.
b: The closest perigee and most distant apogee of the year are marked with “++” if closer in time to full Moon or “–” if closer to new Moon. Other close-to-maximum apogees and perigees are flagged with a single character, again indicating the nearer phase. Following the flags is the interval between the moment of perigee or apogee and the closest new or full phase; extrema cluster on the shorter intervals, with a smaller bias toward months surrounding the Earth’s perihelion in early January.
c: “F” indicates the perigee or apogee is closer to full Moon, and “N” that new Moon is closer. The sign indicates whether the perigee or apogee is before (“-“) or after (“+”) the indicated phase, followed by the interval in days and hours. Scan for plus signs to find “photo opportunities” where the Moon is full close to apogee and perigee
As the relative position of the Sun, Moon and Earth changes, differing proportions of the Moon’s visible surface are illuminated by the Sun. The phases of the Moon are specific instances in this process.
A new Moon occurs when the apparent longitudes of the Moon and Sun differ by 0°. At this time, the Moon does not appear to be illuminated.
Occurs when the apparent longitudes of the Moon and Sun differ by 90°. At this time 50 per cent of the Moon’s visible surface is illuminated.
Occurs when the apparent longitudes of the Moon and Sun differ by 180°. At this time 100 per cent of the Moon’s visible surface is illuminated.
Occurs when the apparent longitudes of the Moon and Sun differ by 270°. At this time 50 per cent of the Moon’s visible surface is illuminated.
Moonrise and moonset
Moonrise is defined as the instant when, in the eastern sky, under ideal meteorological conditions, with standard refraction of the Moon’s rays, the upper edge of the Moon’s disk is coincident with an ideal horizon.
Moonset is defined as the instant when, in the western sky, under ideal meteorological conditions, with standard refraction of the Moon’s rays, the upper edge of the Moon’s disk is coincident with an ideal horizon.
Equinoxes and Solstices
The equinoxes represents either of two times of the year when the Sun crosses the plane of the Earth’s equator and day and night are of equal length, while the solstices is either of the two times of the year when the Sun is at its greatest distance from the celestial equator.
Uploaded on 20 Feb 2012
New images acquired by NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft show that the moon’s crust is being slightly stretched, forming small valleys – at least in some small areas. High-resolution images obtained by the Lunar Reconnaissance Orbiter Camera (LROC) provide evidence that these valleys are very young, suggesting the moon has experienced relatively recent geologic activity.
Smithsonian Institution Senior Scientist Tom Watters explains more about the moon’s recent geological activity in this short video.
by Geoff Gaherty , (Space.Com) Starry Night Education
Date: 13 August 2012
Fact or fiction?
The phases of the moon are caused by the shadow of the Earth falling on the moon.
This is probably the most commonly held misconception in all astronomy. Here’s how the moon’s phases really come about:
The moon is a sphere that travels once around the Earth every 29.5 days. As it does so, it is illuminated from varying angles by the sun. At “new moon,” the moon is between the Earth and sun, so that the side of the moon facing towards us receives no direct sunlight, and is lit only by dim sunlight reflected from the Earth. As it moves around the Earth, the side we can see gradually becomes more illuminated by direct sunlight.
Here’s how the moon changes phases as it orbits the Earth, constantly changing the angle that sunlight hits the moon and is reflected, or not, to our eyes.
CREDIT: Starry Night Software
After a week, the moon is 90 degrees away from the sun in the sky and is half illuminated, what we call “first quarter” because it is about a quarter of the way around the Earth.
A week after this, the moon is 180 degrees away from the sun, so that sun, Earth and moon form a line. The moon is fully illuminated by the sun, so this is called “full moon.” This is the only time in the whole month when the Earth’s shadow is anywhere close to the moon. The Earth’s shadow points towards the moon at this time, but usually the moon passes above or below the shadow and no eclipse occurs.
A week later the moon has moved another quarter of the way around the Earth, to the third quarter position. The sun’s light is now shining on the other half of the visible face of the moon.
Finally, a week later, the moon is back to its new moon starting position. Usually it passes above or below the sun, but occasionally it passes right in front of the sun, and we get an eclipse of the sun.
So, the moon’s phases are not caused by the shadow of the Earth falling on the moon. In fact the shadow of the Earth falls on the moon only twice a year, when there are lunar eclipses.
This article was provided to SPACE.com by Starry Night Education, the leader in space science curriculum solutions.Amateur astronomer Geoff Gaherty operates his own Foxmead Observatory in Coldwater, Ontario, Canada.
Example only; the following Information when Astro’s article was Published
Friday, January 04, 2013, 08:00 UT
381174 km (29.91 Earth diameters)
J2000 Right Ascension, Declination
12h 6m 49s, -5° 5′ 45″
Subsolar Longitude, Latitude
Sub-Earth Longitude, Latitude
The animation archived on this page shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2013, at hourly intervals. Until the end of 2013, the initial Dial-A-Moon image will be the frame from this animation for the current hour.
Published on 20 Nov 2012
This visualization shows the moon’s phase and liberation throughout the year 2013, at hourly intervals. Each frame represents one hour. In addition, this visualization also shows other relevant information, including moon orbit position, sub earth and sub solar points, distance from the Earth. Click each graphic to learn more about what it means! Finally, to learn more about this visualization, or to see what the moon will look like at any hour in 2013, visit http://svs.gsfc.nasa.gov/goto?4000!
The jagged, cratered, airless lunar terrain casts sharp shadows that clearly outline the Moon’s surface features for observers on Earth. This is especially true near the terminator, the line between day and night, where surface features appear in high relief. Elevation measurements by the Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) make it possible to simulate shadows on the Moon’s surface with unprecedented accuracy and detail.
The Moon always keeps the same face to us, but not exactly the same face. Because of the tilt and shape of its orbit, we see the Moon from slightly different angles over the course of a month. When a month is compressed into 24 seconds, as it is in this animation, our changing view of the Moon makes it look like it’s wobbling. This wobble is calledlibration.
The word comes from the Latin for “balance scale” (as does the name of the zodiac constellation Libra) and refers to the way such a scale tips up and down on alternating sides. The sub-Earth point gives the amount of libration in longitude and latitude. The sub-Earth point is also the apparent center of the Moon’s disk and the location on the Moon where the Earth is directly overhead.
The Moon is subject to other motions as well. It appears to roll back and forth around the sub-Earth point. The roll angle is given by the position angle of the axis, which is the angle of the Moon’s north pole relative to celestial north. The Moon also approaches and recedes from us, appearing to grow and shrink. The two extremes, called perigee (near) and apogee (far), differ by more than 10%.
The most noticed monthly variation in the Moon’s appearance is the cycle of phases, caused by the changing angle of the Sun as the Moon orbits the Earth. The cycle begins with the waxing (growing) crescent Moon visible in the west just after sunset. By first quarter, the Moon is high in the sky at sunset and sets around midnight. The full Moon rises at sunset and is high in the sky at midnight. The third quarter Moon is often surprisingly conspicuous in the daylit western sky long after sunrise.
Celestial north is up in these images, corresponding to the view from the northern hemisphere. The descriptions of the print resolution stills also assume a northern hemisphere orientation. To adjust for southern hemisphere views, rotate the images 180 degrees, and substitute “north” for “south” in the descriptions.
The orbit of the Moon in 2013, viewed from the north pole of the ecliptic, with the vernal equinox to the right. The sizes of the Earth and Moon are exaggerated by a factor of 30. The frames include an alpha channel. Duration: 4.9 minutes Available formats: 420×420 MPEG-4 10 MB 420×420 Frames 320×180 PNG 10 KB How to play our movies
From this birdseye view, it’s somewhat easier to see that the phases of the Moon are an effect of the changing angles of the sun, Moon and Earth. The Moon is full when its orbit places it in the middle of the night side of the Earth. First and Third Quarter Moon occur when the Moon is along the day-night line on the Earth.The First Point of Aries is at the 3 o’clock position in the image. The sun is in this direction at the spring equinox. You can check this by freezing the animation at the 1:03 mark, or by freezing the full animation with the time stamp near March 20 at 11:00 UTC. This direction serves as the zero point for both ecliptic longitude and right ascension.The north pole of the Earth is tilted 23.5 degrees toward the 12 o’clock position at the top of the image. The tilt of the Earth is important for understanding why the north pole of the Moon seems to swing back and forth. In the full animation, watch both the orbit and the “gyroscope” Moon in the lower left. The widest swings happen when the Moon is at the 3 o’clock and 9 o’clock positions. When the Moon is at the 3 o’clock position, the ground we’re standing on is tilted to the left when we look at the Moon. At the 9 o’clock position, it’s tilted to the right. The tilt itself doesn’t change. We’re just turned around, looking in the opposite direction.
An animated diagram of the subsolar and sub-Earth points for 2013. The Moon’s north pole, equator, and meridian are indicated. The frames include an alpha channel. Duration: 4.9 minutes Available formats: 320×320 MPEG-4 5 MB 320×320 Frames 320×180 PNG 21 KB How to play our movies
The subsolar and sub-Earth points are the locations on the Moon’s surface where the sun or the Earth are directly overhead, at the zenith. A line pointing straight up at one of these points will be pointing toward the sun or the Earth. The sub-Earth point is also the apparent center of the Moon’s disk as observed from the Earth.In the animation, the blue dot is the sub-Earth point, and the yellow dot is the subsolar point. The lunar latitude and longitude of the sub-Earth point is a measure of the Moon’s libration. For example, when the blue dot moves to the left of the meridian (the line at 0 degrees longitude), an extra bit of the Moon’s western limb is rotating into view, and when it moves above the equator, a bit of the far side beyond the north pole becomes visible.At any given time, half of the Moon is in sunlight, and the subsolar point is in the center of the lit half. Full Moon occurs when the subsolar point is near the center of the Moon’s disk. When the subsolar point is somewhere on the far side of the Moon, observers on Earth see a crescent phase.
An animated diagram of the Moon’s distance from the Earth for 2013. The sizes and distances are true to scale, and the lighting and Earth-tilt are correct. The frames include an alpha channel. Duration: 4.9 minutes Available formats: 1920×1080 MPEG-4 2 MB 1280×720 MPEG-4 1 MB 640×360 MPEG-4 656 KB 1920×1080 Frames (Distance) 320×180 PNG 1 KB How to play our movies
The Moon’s orbit around the Earth isn’t a perfect circle. The orbit is slightly elliptical, and because of that, the Moon’s distance from the Earth varies between 28 and 32 Earth diameters, or about 356,400 and 406,700 kilometers. In each orbit, the smallest distance is called perigee, from Greek words meaning “near earth,” while the greatest distance is called apogee. The Moon looks largest at perigee because that’s when it’s closest to us.The animation follows the imaginary line connecting the Earth and the Moon as it sweeps around the Moon’s orbit. From this vantage point, it’s easy to see the variation in the Moon’s distance. Both the distance and the sizes of the Earth and Moon are to scale in this view. In the full-resolution frames, the Earth is 50 pixels wide, the Moon is 14 pixels wide, and the distance between them is about 1500 pixels, on average.Note too that the Earth appears to go through phases just like the Moon does. For someone standing on the surface of the Moon, the sun and the stars rise and set, but the Earth doesn’t move in the sky. It goes through a monthly sequence of phases as the sun angle changes. The phases are the opposite of the Moon’s. During New Moon here, the Earth is full as viewed from the Moon.
Waxing crescent. Visible toward the southwest in early evening.Available formats: 3600 x 3600 TIFF 8 MB 320 x 320 PNG 280 KB
First quarter. Visible high in the southern sky in early evening.Available formats: 3600 x 3600 TIFF 9 MB 320 x 320 PNG 293 KB
Waxing gibbous. Visible to the southeast in early evening, up for most of the night.Available formats: 3600 x 3600 TIFF 12 MB 320 x 320 PNG 352 KB
Full Moon. Rises at sunset, high in the sky around midnight. Visible all night.Available formats: 3600 x 3600 TIFF 16 MB 320 x 320 PNG 398 KB
Waning gibbous. Rises after sunset, high in the sky after midnight, visible to the southwest after sunrise.Available formats: 3600 x 3600 TIFF 12 MB 320 x 320 PNG 358 KB
Third quarter. Rises around midnight, visible to the south after sunrise.Available formats: 3600 x 3600 TIFF 10 MB 320 x 320 PNG 317 KB
Waning crescent. Low to the east before sunrise.Available formats: 3600 x 3600 TIFF 7 MB 320 x 320 PNG 281 KB
New Moon. By the modern definition, New Moon occurs when the Moon and Sun are at the same geocentric ecliptic longitude. The part of the Moon facing us is completely in shadow then. Pictured here is the traditional New Moon, the earliest visible waxing crescent, which signals the start of a new month in many lunar and lunisolar calendars.Available formats: 3600 x 3600 TIFF 6 MB 320 x 320 PNG 261 KB
Published on 20 Nov 2012
This visualization shows the moon’s phase (Only no detail) and liberation throughout the year 2013, at hourly intervals. Each frame represents one hour
Earth’s only moon is 3,476 km in diameter & orbits at an average distance of 384,400km
By Mark Thompson 24 August 2011
There can be few objects that have inspired both artists and scientists as much as the Moon. Perhaps surprisingly its appearance has barely changed in the thousands of years that mankind has walked the Earth and ancient civilisations enjoyed much the same view as the one we see today. During the Moon’s relentless orbit around the Earth it has witnessed civilisations come and go, entire species evolve and die out and even continents slowly shift. The one thing that has changed over all those years though is our understanding of it, and its still giving us plenty of surprises.
As natural planetary satellites go, the Moon is actually quite large with a diameter of 3,476km (2,155 miles) around the equator. It orbits the Earth at an average distance of 384,400km (238,000 miles) but this varies from its closest, or perigee at 362,570km (225,000 miles) to its most distant point, or apogee of 405,410km (251,000 miles). There are a couple of things people will always think of when you mention the Moon: craters and phases which can both be observed without a telescope.
The phases of the Moon are simple to understand and anyone who has looked at it over a series of nights will notice that it changes progressively night after night with a whole cycle taking about a month. In fact the word month has its origin in the word Moon relating to the approximate length of a full lunar phase cycle. To understand the phases its important to realise that we only see the Moon because it’s a sphere and reflects sunlight – turn the Sun off and the Moon would no longer be visible.
We see the phases change as the Moon orbits around the Earth and the angle between the Sun and Moon alters. During a full Moon, the Sun and Moon are opposite each other in the sky and we see the fully illuminated or daytime face, but at new Moon they are both in the same direction and we see the night time portion of the Moon. As it moves around the Earth, the angle between the Earth, Sun and Moon changes and we see varying amounts of the daytime/nighttime side.The line between the illuminated and un-illuminated faces is called the terminator and its down this line where the Sun is just rising or setting.
From an observational point of view, the surface features are much more prominent if observed when they are near the terminator. The low altitude of the Sun from that point means the shadows cast by the features are much longer making them stand out clearly against the lunar surface. The worst time to observe the Moon is when it’s full and the shadows are minimal.
The phases of the Moon are a little more complicated than I’ve just explained though because the orbit of the Moon around the Earth is very slightly tilted with respect to the Earth’s orbit around the Sun. If it wasn’t then every time we had a full Moon the Earth would block sunlight from reaching the Moon and we would see a lunar eclipse. Clearly we don’t have one every month and its because the Moon’s orbit is tilted that on most occasions the Moon is slightly above or below the Earth’s shadow.
Look at the Moon more closely and you will see dark grey patches, turn binoculars or even a telescope on it and some will turn into great plains while others turn into cavernous craters. The craters were created by meteoric impacts where pieces of space rock smashed into the lunar surface. We see evidence of this process throughout the Solar System even here on Earth. The larger plains, or mare as they are properly called, are the aftermath of much larger impacts that have cracked the lunar surface allowing molten lava to seep up through the mantle. The lava solidifies over time leaving the plains we see today. Before good quality telescopes it was thought these great plains were actually lunar seas.
Another effect of the Moon’s orbit around the Earth are the tides. Like the Earth, the Moon has a gravitational pull and as a result it pulls on the Earth producing a bulge. As the Earth spins once on its axis it ‘passes underneath’ the bulge which we then experience as a tide. There are actually two bulges, one pointing roughly toward the Moon, the other in the opposite direction. When a location passes under the bulge it’s seen as high tide, hence we see two every day.
This bulge is pretty crucial and is having a big impact on the Earth-Moon system. You would think that the bulge lies directly between the Earth and Moon, given that it’s the pull of the Moon’s gravity that causes it. It turns out that the rotation of the Earth drags the bulge a little ahead of the Moon in its orbit. As it lays ahead of the Moon, the extra ‘lump’ of material produces a little extra pull on the Moon causing it to accelerate in its orbit. If you accelerate an orbiting object, it moves into a higher orbit -in other words, it moves further away. Thanks to the Apollo astronauts who left a special mirror on the surface, we can now accurately measure its distance and have found that the Moon is moving away from the Earth at a rate of 3.8cm per year!
It’s not only the Earth that experiences the tides, the Moon too has tides, though to a much lesser degree. The gravitational pull from Earth acts to distort the Moon and produce a lunar tidal bulge toward the Earth. When the Moon first formed it was spinning much faster than it does today and its rotation displaced the tidal bulge from its alignment between the Earth and Moon. The Earth’s gravitational pull still acted upon this bulge causing a braking effect on the Moon’s rotation. Over many millions of years this tidal interaction caused the Moon to slow down so much that it now rotates once on its axis for every orbit around the Earth, every 29.5 days. It’s an effect called captured or synchronous rotation and its result is that we now only ever see one half of the Moon from Earth. In reality we see can see a little more than 50% but this is due to the Moon’s orbital properties allowing us to glance a little further around.
With the Moon moving away from Earth it would be reasonable to assume that at some point they were in the same place. It is believed that the Moon was in fact once part of the Earth. At the time the Earth formed, the Solar System was a war zone with large chunks of rock and proto-planets flying around at ballistic speed. One piece about the size of Mars is thought to have smashed into the Earth throwing vast amounts of material into orbit. It’s believed that most of the heavy elements settled back on Earth while the lighter material stayed in orbit. Recent studies suggest that two moons could have formed, sharing the same orbit, which ultimately collided forming the Moon we see today. This new theory nicely accounts for the observation that one side of the Moon seems to have a much thicker crust which is now thought to be the remains of the Moon’s ancient companion.
Perhaps one of the most incredible discoveries in recent years was the discovery of water ice in some of the deep lunar craters. In these deep craters, that remain almost permanently in shadow, temperatures remain sub zero all year round allowing the ice crystals to form. This discovery opens up tantalising possibilities for future space exploration. The water molecules on the Moon could be harnessed for and purified for future explorers to drink. Taking this a step further, separate the water molecules into their hydrogen and oxygen components and they could be used to create rocket fuel for further onward exploration. No longer can we consider the Moon as a lifeless and hostile place, instead its becoming more likely that mankind’s next step out into the Solar System will involve using the Moon as an outpost for future giant leaps!
The word “quasar” refers to a “quasi-stellar radio source.” The first quasars were discovered in the 1960s when astronomers measured their very strong radio emissions. Later, scientists discovered that quasars are actually radio-quiet, with very little radio emission. However, quasars are some of the brightest and most distant objects we can see.
An artist’s rendering of the most distant quasar
These ultra-bright objects are likely the centers of active galaxies where supermassive black holes reside. As material spirals into the black holes, a large part of the mass is converted to energy. It is this energy that we see. And though smaller than our solar system, a single quasar can outshine an entire galaxy of a hundred billion stars.
To date, astronomers have identified more than a thousand quasars.
Starburst galaxies appear in red. Credit: ESO, APEX (MPIfR/ESO/OSO), A. Weiss et al., Spitzer
By Amanda Doyle at SEN
27 January 2012
(Sen) – Astronomers observing ancient starburst galaxies have made a connection between them and the elliptical galaxies we see today.
There are many different types of galaxies in the Universe and astronomers have long desired to join the dots and solve the puzzles of galaxy evolution. Looking at galaxies that are far, far away is also a way of looking back in time. Their light has taken billions of years to reach us, and thus we see those galaxies as they were billions of years ago. Galaxies in the ancient Universe are often very different than the host of spiral and elliptical galaxies that we are surrounded by today. For example, the extremely bright quasars are common in the distant Universe and yet none exist locally.
However, astronomers using NASA’s Spitzer Space Telescope along with ESO’s Very Large Telescope and 12 metre Atacama Pathfinder Experiment (APEX) telescope have managed to see how distant submillimetre galaxies, quasars, and modern elliptical galaxies fit together in the jigsaw of the Universe.
Sub~millimetre galaxies (SMGs) are situated 10 billion light years from us, and are extremely bright in the infrared region of the spectrum, specifically the submillimetre band. Because the SMGs are located so far away, the light emitted by the galaxies is shifted to much longer wavelengths. These galaxies are also starburst galaxies, meaning that for a short while there is a phenomenal rate of star formation. A supernova explosion would occur every few years and on a planet in a starburst galaxy the night sky would be almost as bright as day.
Astronomers have been able to measure the mass of the dark matter halos surrounding a group of SMGs. Dark matter is invisible and we don’t know what it is, but indirect detections tells us that galaxies are usually engulfed in it. The dark matter typically extends far beyond the edge of the visible galaxy. But measuring the mass of dark matter halos 10 billion light years away is no easy task. Ryan Hickox, lead author of the paper on the subject, explains to Sen how this was done.
“We measure how strongly the galaxies are clustered together in space, using a statistical tool called a ‘correlation function’. If the galaxies were distributed randomly, the correlation function would be equal to zero. However if they are clustered together (sort of like buildings in towns and cities) then they have a positive correlation function. We know from simulations of the Universe how halos of dark matter are clustered together, and this clustering depends strongly on the mass of the halos. Galaxies that live in these halos will be clustered the same way. So by measuring the clustering of the galaxies, we can tell how massive the typical halos that host them are.”
By knowing the mass of the halos of the SMGs, Hickox and his colleagues were able to use computer simulations to fast forward to the present day and show that these galaxies will eventually form giant elliptical galaxies in the modern Universe. However, elliptical galaxies are typically devoid of star formation. So what stopped the immense star formation in the SMGs? Continue Reading
Light that is bent by a galaxy can be used to measure the galaxy’s mass. Credit: Joerg Colberg, Ryan Scranton, Robert Lupton, SDSS
By Amanda Doyle at SEN
14 February 2012
Researchers have used advanced computer simulations to show that the space between galaxies is teeming with dark matter.
Everything that we can see around us in the Universe only makes up around 4.5 per cent of the total mass of the Universe. The remaining “missing mass” is made up of dark matter and dark energy, and the origin of both of these is still a mystery.
While dark matter cannot be directly detected, its presence can be inferred from an effect known as gravitational lensing. Light from a distant object, such as a quasar, is bent around a foreground galaxy so that the light from the quasar becomes distorted. The way in which the light is bent depends on the mass of the “lens” galaxy.
The image on the left shows a simulation of how light from distant sources should appear if there is no intervening “lens,” while the image on the right shows how light can be distorted when there is a galaxy between us and the distant light sources.
However the mass of galaxies is usually much greater than what is expected from looking at the amount of matter that is visible. It has been known for some time that large dark matter halos exist around galaxies, which stretch up to 100 million light years from the centre of the galaxies.
New computer simulations now show that the dark matter does not end at 100 million light years, but instead knows no boundaries as it extends into intergalactic space. Continue Reading
For daily space news follow Sen on Twitter: @sen. They’re also on Google+
Space dot Com Video
Astronomers have found a quasar that’s more than five times more powerful than any previously seen. Quasars are mega-bright geysers of matter and energy powered by super-massive black holes at the centers of young galaxies.
Quasars are the brightest and most distant objects in the known universe. In the early 1960’s, quasars were referred to as radio stars because they were discovered to be a strong source of radio waves. In fact, the term quasar comes from the words, “quasi-stellar radio source”. Today, many astronomers refer to these objects as quasi-stellar objects, or QSOs. As the resolution of our radio and optical telescopes became better, it was noticed that these were not true stars but some type of as yet unknown star-like objects. It also appeared that the radio emissions were coming from a pair of lobes surrounding these faint star-like objects. It was also discovered that these objects were located well outside our own galaxy. Quasars are very mysterious objects. Astronomers today are still not sure exactly what these objects are. What we do know about them is that they emit enormous amounts of energy. They can burn with the energy of a trillion suns. Some quasars are believed to be producing 10 to 100 times more energy than our entire galaxy. All of this energy seems to be produced in an area not much bigger than our solar system.
We do know that quasars are extremely distant. In fact, they may be the most distant objects in the universe. They also have the largest red shift of any other objects in the cosmos. Astronomers are able to measure speed and distance of far away objects by measuring the spectrum of their light. If the colors of this spectrum are shifted toward the red, this means that the object is moving away from us. The greater the red shift, the farther the object and the faster it is moving. Since quasars have such a high red shift, they are extremely far away and are moving away from us at extremely high speeds. It is believed that some quasars may be moving away from us at 240,000 kilometers per second or nearly 80% the speed of light. Quasars are, in fact, the most distant objects to ever be detected in the universe. We know that light travels a certain distance in a year. Quasars are so far away that the light we see when we observe them has been traveling for billions of years to reach us. This means that quasars are among the most ancient objects known in the universe. The most distant quasars observed so far are over 10 billion light-years away. This means we are seeing them as they appeared 10 billion years ago. It is entirely possible that some or all of the quasars we see today may not even exist any more.
Peering back to the early Universe, Europe’s Very Large Telescope has found gas-filled galaxies that lacked the gravity dynamics to form stars. A long-sought faint fluorescent glow was detected, revealing these previously invisible objects.
We still do not know exactly what a quasar is. But the most educated guess points to the possibility that quasars are produced by super massive black holes consuming matter in an acceleration disk. As the matter spins faster and faster, it heats up. The friction between all of the particles would give off enormous amounts of light other forms of radiation such as x-rays. The black hole would be devouring the equivalent mass of one Sun per year. As this matter is crushed out of existence by the black hole, enormous amounts of energy would be ejected along the black hole’s north and south poles. Astronomers refer to these formations as cosmic jets. Another possible explanation for quasars is that they are very young galaxies. Since we know very little about the evolutionary process of galaxies, it is possible that quasars, as old as they are, represent a very early stage in the formation of galaxies. The energy we see may be ejected from the cores of these very young and very active galaxies. Some scientists even believe that quasars are distant points in space where new matter may be entering our universe. This would make them the opposite of black holes. But this is only conjecture. It may be some time before we really understand these strange objects.
The first identified quasar was called 3C 273 and was located in the constellation Virgo. It was discovered by T. Matthews and A. Sandage in 1960. It appeared to be associated with a 16th magnitude star like object. Three years later, in 1963, It was noticed that the object had an extremely high red shift. The true nature of this object became apparent when astronomers discovered that the intense energy was being produced in a relatively small area. Today, quasars are identified primarily by their red shift. If an object is discovered to have a very high red shift and appears to be producing vast amounts of energy, it becomes a prime candidate for quasar research. Today more than 2000 quasars have been identified. The Hubble space telescope has been a key tool in the search for these elusive objects. As technology continues to enhance our windows to the universe, we may one day fully understand these fantastic lights
Pulsars are among the strangest objects in the universe. In 1967, at the Cambridge Observatory, Jocelyn Bell and Anthony Hewish were studying the stars when they stumbled on something quite extraordinary. It was a star-like object that seemed to be emitting quick pulses of radio waves. Radio sources had been known to exist in space for quite some time. But this was the first time anything had been observed to give off such quick pulses. They were as regular as clockwork, pulsing once every second. The signal was originally thought to be coming from an orbiting satellite, but that idea was quickly disproved. After several more of these objects had been found, they were named pulsars because of their rapidly pulsing nature. Bright pulsars have been observed at almost every wavelength of light. Some can actually be seen in visible light. Many people tend to get pulsars confused with quasars. But the two objects are totally different. Quasars are objects that produce enormous amounts of energy and may be the result of a massive black hole at the center of a young galaxy. But a pulsar is a different animal entirely.
Astronomers know of only four “pulsar planets” so far, and much remains unknown about such worlds, but scientists propose that they formed in the chaos after the supernova explosions that gave birth to the pulsars.
A pulsar is a kind of neutron star, a stellar corpse left over from a supernova, a giant star explosion that crushes protons with electrons to form neutrons. Neutron star matter is the densest known material: A sugar cube-size piece weighs as much as a mountain, about 100 million tons. The mass of a single neutron star surpasses that of the sun while fitting into a ball smaller in diameter than the city of London.
The Lighthouse Factor
A pulsar is basically a rapidly spinning neutron star. A neutron star is the highly compacted core of a dead star, left behind in a supernova explosion. This neutron star has a powerful magnetic field. In fact, this magnetic field is about one trillion times as powerful as the magnetic field of the Earth. The magnetic field causes the neutron star to emit strong radio waves and radioactive particles from its north and south poles. These particles can include a variety of radiation, including visible light. Pulsars that emit powerful gamma rays are known as gamma ray pulsars. If the neutron star happens to be aligned so that the poles face the Earth, we see the radio waves every time one of the poles rotates into our line of sight. It is a similar effect as that of a lighthouse. As the lighthouse rotates, its light appears to a stationary observer to blink on and off. In the same way, the pulsar appears to be blinking as its rotating poles sweep past the Earth. Different pulsars pulse at different rates, depending on the size and mass of the neutron star. Sometimes a pulsar may have a binary companion. In some cases, the pulsar may begin to draw in matter from this companion. this can cause the pulsar to rotate even faster. The fastest pulsars can pulse at well over a hundred times a second
Excitement is riding high in the astronomical community with the recent discovery of Comet ISON, which is destined to pass exceedingly close to the sun in late November 2013 and might possibly become dazzlingly bright.
The latest information issued by NASA’s Jet Propulsion Laboratory suggests that this comet could get as bright as magnitude -11.6 on the astronomers’ brightness scale; that’s as bright as nearly full moon! That would also be bright enough for Comet ISON to be visible during the daytime.
Comets that are visible to the naked eye during the daytime are rare, but such cases are not unique. In the last 332 years, it has happened only nine other times. Here is a listing of past comets that have achieved this amazing feat.
In this list we quote the brightness of the comets in terms of magnitude. On this scale, larger numbers represent dimmer objects; the brightest stars are generally zero to first magnitude, while super-bright objects such as Venus and the moon achieve negative magnitudes. [Spectacular Comet Photos (Gallery)]
Great Comet of 1680 —This comet has an orbit strikingly similar to Comet ISON, begging the question of whether both objects are one and the same or at the very least are somehow related. Discovered on Nov. 14, 1680 by German astronomer Gottfried Kirsch, this was the first telescopic comet discovery in history. By Dec. 4, the comet was visible at magnitude +2 with a tail 15 degrees long. On Dec. 18 it arrived at perihelion — its closest approach to the sun — at a distance of 744,000 miles (1.2 million kilometers).
A report from Albany, N.Y. indicated that it could be glimpsed in daylight passing above the sun. In late December, it reappeared in the western evening sky, again of magnitude +2, and displaying a long tail that resembled a narrow beam of light that stretched for at least 70 degrees. The comet faded from naked-eye visibility by early February 1681.
Great Comet of 1744 — First sighted on Nov. 29, 1743 as a dim 4th-magnitude object, this comet brightened rapidly as it approached the sun. Many textbooks often cite Philippe Loys de Cheseaux, of Lausanne, Switzerland as the discoverer, although his first sighting did not come until two weeks later. By mid-January 1744, the comet was described as 1st-magnitude with a 7-degree tail.
By Feb. 1 it rivaled the star Sirius in brightness and displayed a curved tail 15 degrees in length. By Feb. 18 the comet was as bright as Venus and now displayed two tails. On Feb. 27, it peaked at magnitude -7 and was reported visible in the daytime, 12 degrees from the sun. Perihelion came on March 1, at a distance of 20.5 million miles (33 million km) from the sun. On March 6, the comet appeared in the morning sky, accompanied by six brilliant tails that resembled a Japanese hand fan.
Great Comet of 1843 — This comet was a member of the Kruetz Sungrazing Comet Group, which has produced some of the most brilliant comets in recorded history. Such comets actually graze through the outer atmosphere of the sun, and often do not survive.
The 1843 comet passed only 126,000 miles (203,000 km) from the sun’s photosphere on Feb 27, 1843. Although a few observations suggest that it was seen for a few weeks prior to this date, on the day when of its closest approach to the sun it was widely observed in full daylight. Positioned only 1 degree from the sun, this comet appeared as “an elongated white cloud” possessing a brilliant nucleus and a tail about 1 degree in length. Passengers onboard the ship Owen Glendower, off the Cape of Good Hope described it as a “short, dagger-like object” that closely followed the sun toward the western horizon.
In the days that followed, as the comet moved away from the sun, it diminished in brightness but its tail grew enormously, eventually attaining a length of 200 million miles (320 million km). If you were able to place the head of this comet at the sun’s position, the tail would have extended beyond the orbit of the planet Mars!
A chromolithograph of the great comet of 1881 by Trouvelot CREDIT: E.L. Trouvelot/NYPL
Great September Comet of 1882 — This comet is perhaps the brightest comet that has ever been seen; a gigantic member of the Kreutz Sungrazing Group. First spotted as a bright zero-magnitude object by a group of Italian sailors in the Southern Hemisphere on Sept.1, this comet brightened dramatically as it approached its rendezvous with the sun.
By Sept. 14, it became visible in broad daylight and when it arrived at perihelion on the 17th, it passed at a distance of only 264,000 miles (425,000 km) from the sun’s surface. On that day, some observers described the comet’s silvery radiance as scarcely fainter than the limb of the sun, suggesting a magnitude somewhere between -15 and -20!
The following day, observers in Cordoba, Spain described the comet as a “blazing star” near the sun. The nucleus also broke into at least four separate parts. In the days and weeks that followed, the comet became visible in the morning sky as an immense object sporting a brilliant tail. Today, some comet historians consider it as a “Super Comet,” far above the run of even Great Comets.
Great January Comet of 1910 — The first people to see this comet — then already at first magnitude — were workmen at the Transvaal Premier Diamond Mine in South Africa on Jan. 13, 1910. Two days later, three men at a railway station in nearby Kopjes casually watched the object for 20 minutes before sunrise, assuming that it was Halley’s Comet.
Later that morning, the editor of the local Johannesburg newspaper telephoned the Transvaal Observatory for a comment. The observatory’s director, Robert Innes, must have initially thought this sighting was a mistake, since Halley’s Comet was not in that part of the sky and nowhere near as conspicuous. Innes looked for the comet the following morning, but clouds thwarted his view. However, on the morning of Jan. 17, he and an assistant saw the comet, shining sedately on the horizon just above where the sun was about to rise. Later, at midday, Innes viewed it as a snowy-white object, brighter than Venus, several degrees from the sun. He sent out a telegram alerting the world to expect “Drake’s Comet” — for so “Great Comet” sounded to the telegraph operator.
It was visible during the daytime for a couple more days, then moved northward and away from the sun, becoming a stupendous object in the evening sky for the rest of January in the Northern Hemisphere. Ironically, many people in 1910 who thought they had seen Halley’s Comet instead likely saw the Great January Comet that appeared about three months before Halley. [Photos of Halley’s Comet Through History]
Comet Skjellerup-Maristanny, 1927 —Another brilliant comet, first seen as a 3rd magnitude object in early December 1927, had the unfortunate distinction of arriving under the poorest observing circumstances possible. The orbital geometry was such that the approaching comet could not be seen in a dark sky at any time from either the Northern or the Southern Hemisphere.
Nonetheless, the comet reached tremendous magnitude at perihelion on Dec. 18. Located at a distance of 16.7 million miles (26.9 million km) from the sun, it was visible in daylight about 5 degrees from the sun at a magnitude of -6. As the comet moved out of the twilight and headed south into darker skies, it faded rapidly, but still threw off an impressively long tail that reached up to 40 degrees in length by the end of the month.
This painting of Comet Ikeya-Seki, visible during the day, was done by now-retired Hayden Planetarium artist Helmut K. Wimmer and was based on a description made by Hayden’s Chief Astronomer, Ken Franklin, from an airplane hovering over West Point, New York. It was originally published in the February 1966 issue of Natural History magazine. Republished with permission.
Comet Ikeya-Seki, 1965 — This was the brightest comet of the 20th century, and was found just over a month before it made perihelion passage in the morning sky, moving rapidly toward the sun.
Like the Great Comets of 1843 and 1882, Ikeya-Seki was a Kreutz Sungrazer, and on Oct. 21, 1965, it swept within 744,000 miles (1.2 million km) of the center of the sun. The comet was then visible as a brilliant object within a degree or two of the sun, and wherever the sky was clear, the comet could be seen by observers merely by blocking out the sun with their hands.
From Japan, the homeland of the observers who discovered it, Ikeya-Seki was described as appearing “ten times brighter than the full moon,” corresponding to a magnitude of -15. Also at that time, the comet’s nucleus was observed to break into two or three pieces. Thereafter, the comet moved away in full retreat from the sun, its head fading very rapidly but its slender, twisted tail reaching out into space for up to 75 million miles (120 million km), and dominating the eastern morning sky right on through the month of November.
Comet West, 1976 — This comet developed into a beautiful object in the morning sky of early March 1976 for Northern Hemisphere observers. It was discovered in November 1975 by Danish astronomer Richard West in photographs taken at the European Southern Observatory in Chile. Seventeen hours after passing within 18.3 million miles (29.5 million km) of the sun on Feb. 25, 1976, it was glimpsed with the naked eye 10 minutes before sunset by John Bortle.
In the days that followed, Comet West displayed a brilliant head and a long, strongly structured tail that resembled “a fantastic fountain of light.” Sadly, having been “burned” by the poor performance of Comet Kohoutek two years earlier, the mainstream media all but ignored Comet West, so most people unfortunately failed to see its dazzling performance.
Michael Jager and Gerald Rhemann photographed comet C/2006 P1 (McNaught) from Austria in twilight 45 minutes before sunrise on Jan. 3. Rhemann told SPACE.com they used 7×50 binoculars to find the comet. They estimate that today (Jan. 5) it shone at magnitude +1 and they expect to see it with the naked eye next week.
Comet McNaught, 2007 —Discovered in August 2006 by astronomer Robert McNaught at Australia’s Siding Spring Observatory, this comet evolved into a brilliant object as it swept past the sun on Jan. 12, 2007 at a distance of just 15.9 million miles (25.6 million km). According to reports received from a worldwide audience at the International Comet Quarterly, it appears that the comet reached peak brightness on Sunday, Jan. 14 at around 12 hours UT (7:00 a.m. EST, or 1200 GMT). At that time, the comet was shining at magnitude 5.1.
Some observers, such as Steve O’Meara, located at Volcano, Hawaii, observed McNaught in daylight and estimated a magnitude as high as -6, noting, “The comet appeared much brighter than Venus!”
After passing the sun, Comet McNaught developed a stupendously large, fan-shaped tail somewhat reminiscent of the Great Comet of 1744. Unfortunately for Northern Hemisphere observers, the best views of Comet McNaught were mainly from south of the equator.
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.