Eclipse

The sun's corona surrounds the dark silhouette of the moon during the March 29, 2006, total solar eclipse. Coronal streamers and polar plumes are held in place by the sun's magnetic field.  (Jay M. Pasachoff and Miloslav Druckmüller) licensed under Creative Commons CC-by-nc-nd/3.0 http://www.flickr.com/photos/24701402@N03/2336329282/ 

Introduction

An eclipse is when one astronomical body hides another as seen from a third.  Though mainly applied to eclipses of the sun or of the moon as seen from Earth, more distant astronomical bodies can also eclipse each other.

Streamers in the solar corona extend from the moon at the total solar eclipse of March 29, 2006. (Jay M. Pasachoff and Miloslav Druckmüller)
licensed under Creative Commons CC-by-nc-nd/3.0
http://www.flickr.com/photos/24701402@N03/2335495525/ 

Eclipses of the Sun

The moon's diameter is about 400 times smaller than that of the sun, but it is also about 400 times closer.  As a result, both the moon and the sun appear about the same size in the sky.  Consequently, when the moon goes in front of the sun, it blocks that everyday sun, cutting the sunlight reaching us on Earth.  If the Earth, moon, and sun are perfectly aligned, when the moon completely blocks the sun we have a total solar eclipse.

At a total solar eclipse, the bright everyday sun, known as the photosphere (from the Greek: the sphere the light comes from) is hidden.  The sky darkens by a factor of about a million, so that it is merely as dark as twilight or as a full moon on Earth.  Without the normal blue sky of the daytime, which arises when light from the photosphere hits the Earth's atmosphere and scatters around in it, faint outer layers of the sun come into view.

Such an eclipse occurs somewhere in the world about every 18 months.  But if you wait at one average location on Earth without traveling, total solar eclipses don't again appear for about 300 years.  (A few specific spots, though, can have total solar eclipses twice within a year.)

What does a total solar eclipse look like?

At a total solar eclipse, first the moon begins to cover the sun.  When the moon's silhouette first touches the sun, we have first contact.  The interval of partial eclipse, until the moon entirely covers the photosphere, is approximately two hours.  Just before the moon entirely covers the sun, the sky darkens so much that the reddish solar chromosphere and the pearly white solar corona become visible.  Since the moon's edge is irregular, a few beads of bright sunlight come through the valleys between the mountains on the moon, and are called Baily's beads.  The last Baily's bead seems so bright compared with anything else in the sky that it is known as the diamond ring effect.  The Baily's beads last less than a minute and the diamond ring effect lasts only a few seconds.  When the diamond ring is extinguished, we have second contact, with the moon's silhouette entirely covering the solar photosphere.  Second contact marks the beginning of totality.  Within a few more seconds, the reddish solar chromosphere is also covered by the advancing moon.

During totality, which can last from a fraction of a second up to approximately seven minutes, amateur astronomers and tourists gaze in awe at the phenomenon occurring in the sky, while the surrounding darkness that rapidly occurred may induce a primal feeling of anxiety.  Professional astronomers use the brief time to study the solar corona, using recent instruments or recent theoretical ideas to learn how it is heated to temperatures of millions of degrees or to study motions within it.  Further, they study how the sun's magnetic field holds this million-degree gas into beautiful shapes, providing information that can lead to improvements in scientists' understanding of the physical mechanisms that we also desire to use to hold hot gases into place on Earth to provide power through nuclear fusion.

During the seconds or minutes of totality, the sky is sufficiently dark that stars and planets become visible.  Mercury is perhaps more commonly seen at total eclipses than at other times, when it is never far from the horizon at sunset or sunrise.  Eclipse darkness was famously used in 1919 and 1922 to test Einstein's general theory of relativity, which predicted that the sun's mass would apparently bend light (by warping space) enough to displace slightly the positions of stars near the sun.  During the 1919 eclipse, the sun fortuitously was located in a cluster of stars during totality.  When the results became known, Einstein immediately gained his lasting fame with scientists and with the public.  His prediction has been better verified by other means in recent years, though, so eclipses are no longer used for testing relativity.

All too briefly, the phenomena that marked second contact occur in reverse to mark third contact.  The chromosphere becomes visible followed by a second diamond ring and then an increasing set of Baily's beads.  The abrupt return of sunlight with the diamond ring brightens the sky so much that views of the corona are quickly lost.  The final partial phases, through fourth (and last) contact, again take hours, though relatively few observers bother to watch them all, since the main glory of the eclipse has passed.

As a rule, the chromosphere is about a thousand times fainter than the everyday sun and the corona is about a million times fainter, about the same brightness as a full moon.

 

The paths of total and annular solar eclipses from 2001 to 2020 (Fred Espenak, NASA's Goddard Space Flight Center)
licensed under Creative Commons CC-by-nc-nd/3.0
http://www.flickr.com/photos/24701402@N03/2336329406/ 

When were the last total solar eclipses?

 • August 1, 2008: The eclipse started in islands of northern Canada, passed over Greenland, and descended through Siberia to western Mongolia and adjacent China.  Novosibirsk, the third largest Russian city, was in the path.  Successful observations were made from airplanes near Greenland and across most sites in Russia, Mongolia, and China, with only a small percentage of observers bothered by cloudiness.

A ground-based total solar eclipse image from Akademgorodok, Siberia, in Russia on August 1, 2008, merged with two space images from the ESA/NASA SOHO spacecraft.  (credit: Eclipse image credit: Williams College Eclipse Expedition: Jay M. Pasachoff, Bryce A. Babcock, William G. Wagner, Matthew Baldwin, Katherine DuPré, Marcus Freeman, Marek Demianski, Paul Rosenthal; disk image from Extreme-Ultraviolet Telescope team, NASA's Goddard Space Flight Center; outer image from Naval Research Laboratory/SOHO is a joint project of the European Space Agency and NASA; compositing by Steele Hill, NASA's Goddard Space Flight Center)

licensed under Creative Commons CC-by-nc-nd/3.0

A ground-based total solar eclipse image from Tianhuangping, in China, on July 22, 2009, merged with two space images from the ESA/NASA SOHO spacecraft.  The corona was sparse, given the low level of solar activity as the minimum of the sunspot cycle continued.  (credit: Eclipse image credit: Williams College Eclipse Expedition: Jay M. Pasachoff, Bryce A. Babcock, Katherine DuPré, Sara Dwyer, Rachel Wagner-Kaiser, Yung Hsien Ng Tam, and Huajie Cao; disk image from Extreme-Ultraviolet Telescope team, NASA's Goddard Space Flight Center; outer image from Naval Research Laboratory/SOHO is a joint project of the European Space Agency and NASA; compositing by Steele Hill, NASA's Goddard Space Flight Center)

licensed under Creative Commons CC-by-nc-nd/3.0

• July 22, 2009: The eclipse passed over India, though during the monsoon season when clear skies were rare.  Most observers were in China, where such large cities as Shanghai, Hangzhou, and Wuhan were within the path of totality.  Visibiity was spotty, with a few sites clear many sites having visibility of the eclipse phenomena through clouds, and some sites (notably the Shanghai region) rainy.  About 5 minutes 40 seconds of totality was the duration in eastern China.  Several ships intersected the path of totality in the Pacific with about 6 minutes 40 seconds of totality.  Clear observations were gotten from Enewetak atoll, Marshall Islands, with 5 minutes 40 seconds of totality.

interactive map of the 2009 total eclipse 
Miloslav Druckmüller's images

When are the next total solar eclipses?

interactive map of the 2010 total eclipse 
Jay Anderson's weather predictions

The next total solar eclipse that crosses the United States will be on August 21, 2017.  The path of totality will extend from the Pacific Northwest to the southeast.  Totality will reach the coast centered on Salem, Oregon, though Portland will be just out of totality to the north.  It will pass Kansas City and Nashville and Knoxville, Tennessee, reaching the east coast including Columbia, South Carolina's 2½ minutes of totality.  The rest of the United States, Canada, Mexico, Central America, and northern South America will have a partial eclipse.  Several eclipses after that, the total solar eclipse of April 8, 2024, will cross the United States from central Texas to northern New England, including such cities as Austin and Dallas (Texas), Cleveland (Ohio), Erie (Pennsylvania), and Buffalo and Rochester (New York).

interactive map of the 2017 total eclipse 

When are the next annular or partial solar eclipses visible in the United States?

Annular solar eclipses

The moon's silhouette can be a few percent bigger than the sun's, leading to a total eclipse, but it can also be a few percent smaller.  When the moon is relatively far from the Earth in its elliptical orbit and, to a lesser degree, the Earth is relatively close to the sun, the moon does not cover the solar photosphere even when it passes centrally across it.  A ring, or annulus, of everyday, photospheric sunlight remains.  This type of eclipse is called annular.

An annular eclipse can last up to about 12 minutes.  Annular eclipses occur, on the average, at about the same rate as total eclipses: about every 18 months.  One sees a partial eclipse first for perhaps a couple of hours, and then Baily's beads at second contact.  In fact, Francis Baily reported the beads now named after him (they had been previously reported as well) at an annular eclipse).  But in an annular eclipse, with perhaps 7% of the photosphere's area remaining visible (and even with a much smaller remaining area), the blue sky remains sufficiently bright that one cannot see the solar corona.

Occasionally, an eclipse is total at its path's center, when the tip of the moon's shadow barely touches the Earth, but is annular at one or both ends of the path.  These annular-total eclipses are also known as hybrid eclipses.

How often are solar eclipses visible on Earth?

When was the last annular solar eclipse?

 • January 26, 2009: The annular phase was seen in parts of Indonesia, especially western Java (through haze) and eastern Sumatra.  Australia's Cocos Islands were under cloudy and rainy weather.  Partial phases were seen elsewhere in southeast Asia, such as the Philippines and western Australia.

The January 26, 2009, annular eclipse from National Geographic News. 

When are the next annular solar eclipses?

• January 15, 2010: The eclipse passes over the Maldive islands, southernmost India, northmost Sri Lanka, southernmost Bangladesh, and Myanmar before going into China, where it goes south of Chengdu and north of Shanghai.

interactive map of the 2010 annular eclipse 

• May 20, 2012: The path of annularity starts in China, including Guangzhou and Hong Kong, leaving China at Fuzhou.  It crosses eastern Japan (4 min 19 s), including Tokyo (4 min 4 s).  After reaching its peak in mid-Pacific, it will be visible from the northwestern United States, as far as Crescent City (4 min 45 s) and Eureka (4 min 00 s), California; Reno, Nevada (4 min 25 s); Albuquerque, New Mexico (4 min 26 s); and Lubbock, Texas (4 min 14 s but only about 1° above the horizon + any effect of altitude from refraction).  Partial phases will be visible throughout the United States and Canada except for the extreme northeast.  88% of the sun will be covered.

interactive map of the 2012 annular eclipse 

Observing solar eclipses safely

One often reads that one goes blind by looking at the sun.  This statement is an exaggeration, since clearly the sun passes through the field of view of many of us very often.  The correct statement is "Don't stare at the sun, unless you are looking through a proper solar filter."

Normally, an eye-blink reflex causes us to close our eyes when the sun comes into view.  But in the last minutes of a total solar eclipse, the total amount of sunlight can be sufficiently diminished that the eye-blink reflex doesn't work yet the crescent sun is bright enough that it can burn the retina.  Sometimes such injuries are permanent, though at other times they can heal.  Further, with enough bright sun, the inside of the eye can become hot enough to cause a thermal injury.

But various types of filters cut down the solar brightness by a factor of approximately 100,000, making the brightness roughly that of the full moon and no more dangerous.  The most widespread and least expensive of these filters are made from aluminized Mylar.  They are often mounted in 3"x4" cards or even in cardboard glasses.  One should always search for certification that such solar filters are safe, looking for official certifications and also making sure you can't see an ordinary light bulb through them and that there are no tiny holes ("pinholes") through which sunlight passes.

Note that these "solar filters" are for use only when all or part of the everyday sun is visible, not hidden behind the moon.  During totality, one looks at the totally eclipsed sun directly, without filters.  Indeed, the corona is so faint—only about the brightness of the full moon—that you wouldn't see it at all if you still had the "solar filter" before your eyes.  The filters would better be called "partial-eclipse filters."

Looking at the partial phase of the February 7, 2008, solar eclipse through a solar filter that reflects most of the sunlight, letting only about 0.001% through. (Jay M. Pasachoff)
licensed under Creative Commons CC-by-nc-nd/3.0

http://www.flickr.com/photos/24701402@N03/2335505841/  

More expensive filters come from aluminum deposited on glass; such filters are commonly available at telescope providers and other astronomical-goods companies.  Welders glass of grades 13 and above are also safe, though the images through them are not always of the best quality.

Fogged and exposed black-and-white film that contains silver can also be used, but newer black-and-white films, often those that can be developed with the same chemistry as color films, are not safe because they let too much infrared radiation through to be safe.  Traditional x-ray films, fogged and developed are good--but you have to look through the darkest parts and not the images of bones!  Some CD-ROM's or DVD's cut down the solar brightness sufficiently, but novice observers can't be sure of the fraction of light they allow through so it is best not to use them--and certainly don't try to look through the central holes, as has been reported.

Though a glance at the crescent, partly eclipsed sun with the unaided eye isn't unsafe, a mere glance through a telescope or binocular, with the sun focused, can be instantly and permanently harmful.  Anyone using a solar filter with a telescope should be careful that the filter is free of cracks or pinhole leaks, firmly affixed, and placed at the front of the telescope, since it could burn or be cracked at the eyepiece end, and that it is pinhole free and firmly affixed.

One can safely look at the partial phases of an eclipse with a pinhole camera, quickly and cheaply made by simply punching a hole in a piece of cardboard and using that hole to project a solar image on the wall or floor.  Then you are standing with the sun at your back; never look up through the hole.

Note that the advice sometimes given to people that the safest way to observe a total eclipse is to watch it on television misses the point about the joy of experiencing one of nature's greatest natural phenomena.  The glory of a total solar eclipse is not merely in the details of the structure of the corona, but includes experiencing the tremendous changes in the Earth's atmosphere over a short interval.  Television images of eclipse lose most of the excitement and the depth of the unusual and pleasurable experience.

Giving correct information about the hazards and value of observing eclipses can be an important matter of public safety.  Children and adults, if they discover that public authorities have given false warnings of hazards at eclipses or otherwise, will in the future not trust the accuracy of other warnings.  Thus the authorities who exaggerate the hazards of observing eclipses risk their readers and listeners winding up with greater risks, since warnings about drugs, smoking, and other noncontroversial hazards may not be taken as seriously.  The children who are locked in rooms by school authorities so as not to risk their looking at a total eclipse may wind up at greater risk, since they will soon after talk to people who saw the eclipse and realize that they had not been given accurate information about eclipse hazards.  

Using a grater to make many pinholes in order to make hundreds of pinhole images (just for fun) of the partially eclipsed sun at the solar eclipse of February 7, 2008. (Jay M. Pasachoff)
licensed under Creative Commons CC-by-nc-nd/3.0
http://www.flickr.com/photos/24701402@N03/2335506371/ 

Using a grater to make many pinholes in order to make hundreds of pinhole images of the partially eclipsed sun at the solar eclipse of February 7, 2008. (Jay M. Pasachoff)
licensed under Creative Commons CC-by-nc-nd/3.0

http://www.flickr.com/photos/24701402@N03/2336340434/ 

Science at solar eclipses

That the solar corona is part of the sun's atmosphere and not part of the moon's is a result from a 19th-century total solar eclipse, as is the discovery of helium, a gas first found only in the sun and therefore named after the Greek sun god, Helios.  Soon thereafter, another eclipse spectrum of the corona seemed to show a different unknown element, which was analogously given the name "coronium."  In the first half of the 20th century, it was found that the corona is millions of degrees in temperature by studying its spectrum. Theoretical work on the spectrum identified the spectral radiations previously known as coronium as extreme ions of common elements rather than as its own element.  Thus helium turned out to be a real discovery from study of an eclipse spectrum, while coronium turned out merely to be a false interpretation of  a spectrum resulting from iron and other elements at high coronal temperatures.

But by the 21st century, spacecraft enabled the sun to be under constant surveillance.  Spectra of the sun in the ultraviolet and x-ray regions of the spectrum revealed emissions typical of million-degree temperatures and allowed temperature maps of the sun to be made.  Time-lapse movies showed eruptions and other motions in the corona.  Coronagraphs, telescopes that blocked the solar photosphere, allowed the shape of the outer corona to be followed on an hourly basis.

Still, even with several solar spacecraft from various nations aloft, various parts of the corona can best be studied scientifically at eclipses.  For example, the spacecraft thus far cannot take images more often than every few seconds, so eclipse observations at cadences faster than that are unique.  Such observations can bear on theoretical models of coronal heating.  Coronagraphs, such as those from the U.S. Naval Research Laboratory  on the European Space Agency's Solar and Heliospheric Observatory, launched in 1995, have to hide not only the photosphere but also a considerable region around it.  Such regions are exactly those that are seen at total eclipses, so compound images taken on eclipse day and containing both space and ground-based eclipse images reveal the whole extent of the corona, from the base of coronal streamers on the solar surface, seen in the ultraviolet from spacecraft, through the lower and middle corona seen at eclipse and through the outer corona seen from spacecraft.  The Japanese Hinode spacecraft, launched in 2006, carries an American X-Ray Telescope from the Smithsonian Astrophysical Observatory that reveals the corona on the solar surface in high detail, giving images that will be compared with eclipse images at every opportunity.  The eclipse images, especially when processed with new methods of computer analysis, reveal finer spatial detail in the corona than is available from spacecraft coronagraph images.

Other advances in coronal research can be made with types of instrumentation that aren't carried on current spacecraft, such as spectrographs that take spectra of the emissions from highly ionized coronal gases for a two-dimensional set of positions.  Observations of the continuous rainbow of spectrum and of emissions from specific ions with infrared detectors are among the unique observations to be carried out at contemporary eclipses.  Polarization measurements of the coronal continuous radiation and of the spectral lines are other current scientific objectives.

Eclipse research, coupled with simultaneous observations from spacecraft, remains a viable part of solar investigations.  The lower and middle corona, which are not visible from spacecraft, are the locations where the solar wind is accelerated and where coronal mass ejections are in their infancy.  Ground-based eclipse observations contribute to their study.

Links to review articles on the scientific value of eclipses

Eclipses of the Moon

At a total eclipse of the moon, the moon actually moves completely into Earth's shadow in space.  This shadow is more than twice the moon's diameter, so the moon remains in the shadow and therefore totally eclipsed for a couple of hours.

Actually, the darkest part of the Earth's shadow, the umbra, is a cone that tapers with distance from Earth, though it is still much wider than the moon at the moon's distance from Earth of 238,000 miles (400,000 kilometers).  From the region around the umbra, the penumbra, part of the sun is visible.

When the moon is totally eclipsed, completely in the umbra, nonetheless some sunlight is bent around the edge of the Earth by Earth's atmosphere.  The blue component of that light is largely scattered out to make blue skies for the people on Earth below it, leaving mainly red light to reach the moon.  A totally eclipsed moon therefore glows faintly red in the sky, much darker than the full moon it replaced.  The total phase of a lunar eclipse lasts approximately an hour. 

The end of the partial phases before totality at the total lunar eclipse of February 20/21, 2008, already showing the reddish light bent around the Earth to hit the moon while a crescent of only partially eclipsed moon remains relatively bright. (Jay M. Pasachoff)
licensed under Creative Commons CC-by-nc-nd/3.0
http://www.flickr.com/photos/24701402@N03/2336340478/ 

For an hour and a half or so prior to the total eclipse, the moon moves gradually into the Earth's shadow, providing a partial lunar eclipse.  Prior to that, the outer part of the Earth's shadow, from which only part of the everyday solar surface is visible, provides a penumbral lunar eclipse, which is hardly noticeable.

That the shadow of the Earth as visible on the Moon is round has shown for thousands of years that the Earth is round.  The story that Columbus in 1492  didn't know that the Earth was round is but a myth.

Observing a lunar eclipse

The moon at a lunar eclipse is an especially good full moon, one that occurs when the moon in its orbit is near a node when the lunar orbit crosses the plane of the Earth's orbit around the sun.  Projected onto the sky, a lunar eclipse occurs when the moon is near the crossing point of its path in the sky with sun's path, though the sun at that time is on the opposite side of the Earth.

Since the sun and moon move sufficiently slowly on their orbits, there are always solar and lunar eclipses separated by two weeks from each other, though one or both may be partial.  By the time the moon has moved halfway around the Earth during that two-week interval, the tilt of its orbit has not been enough to raise it high enough to avoid having that second eclipse.

The moon's surface brightness is about the same as that on Earth, since both Earth and moon are about the same distance from the sun.  It is therefore always safe to look at the moon with your eye or with binoculars or telescopes.  During an eclipse, there is even less moonlight reflecting back toward us than at other times.  The full moon is sufficiently bright that only the brightest stars are visible in the sky; during a total lunar eclipse, fainter stars become visible.

Decades ago, before crewed and robotic spacecraft were sent to the moon, some scientific results could be gleaned at lunar eclipses.  For example, the thermal properties of the lunar surface could be monitored as parts of the lunar surface cooled.  But such investigations were superseded by spacecraft measurements and even by the Apollo astronauts directly, so no scientific research is now carried out at lunar eclipses.

The darkness of the totally eclipsed moon reveals the particle content of the Earth's atmosphere, since the reddishness is light that has come through the Earth's atmosphere.  Volcanic eruptions put particles into our atmosphere that absorb sunlight, making the lunar disk relatively dark.  The darknesses of lunar eclipses are rated on the Danjon scale, from L=0 for total eclipses in which the lunar disk is almost invisible during totality to L=4 for total eclipses in which the moon appears relatively bright and reddish, though still much dimmer than the full moon it replaced.

When are the next lunar eclipses?

• December 31, 2009: A partial eclipse will be visible across Eurasia, with some partial phases visible from New England in the United States and eastern Canada.

• December 21, 2010: A total lunar eclipse will be visible across the Americas.

The next total lunar eclipses to be visible from North America will be on April 15, 2014, December 8, 2014, April 4, 2015 (western North America only), and September 27, 2015.

There are always at least two lunar eclipses per year, though they can be merely partial.

Other eclipses

A class of double star known as eclipsing binaries have two components that go in front of each other.  As seen from Earth, the total brightness of the combined pair diminishes during the eclipses.  

A prominent example of an eclipsing binary star is Algol, known as the Demon Star.  It is beta Persei, the second brightest star in Perseus.  Every 2.9 days, on a predictable schedule, it drops from magnitude 2.2 to 3.4, a drop by a factor of over 3.

When one astronomical body goes in front of another, a transit, as in a transit of Venus across the face of the sun or a transit of an exoplanet across the face of its star, is equivalent to an annular eclipse.  Transit implies that a body of smaller angular size is going in front of a body of larger angular size.  When the nearer body completely hides the farther body, that type of eclipse is called an occultation.  For example, Pluto occasionally occults stars, allowing Pluto's atmosphere to be studied as it bends and absorbs the starlight.  Many exoplanet transits across the faces of their parent stars are being observed, for example, by NASA's Kepler spacecraft.

More Information

Web Resources

International Astronomical Union Working Group on Eclipses: http://www.eclipses.info 
NASA's Eclipse Web Site: http://eclipse.gsfc.nasa.gov/eclipse.html 
Fred Espenak: Fifty Year Canon of Solar Eclipses: 1986 - 2035: http://eclipse.gsfc.nasa.gov/SEpubs/RP1178.html 
Fred Espenak and Jean Meeus: Five Millennium Canon of Solar Eclipses: –1999 to +3000 (2000 BCE to 3000 CAE): http://eclipse.gsfc.nasa.gov/SEpubs/5MCSE.html 
Fred Espenak: Five Millennium Canon of Lunar Eclipses: –1999 to +3000 (2000 BCE to 3000 CAE): http://eclipse.gsfc.nasa.gov/LEcat/LEcatalog.html 
Eclipse images from Williams College: http://www.williams.edu/astronomy/eclipse 
Eclipse images from Fred Espenak: http://www.mreclipse.com 
Maps and weather from Jay Anderson: http://home.cc.umanitoba.ca/~jander/ 
Solar eclipse links from the Poitevins: http://uk.geocities.com/solareclipsewebpages@btopenworld.com/SELinks.html 
Solar links from Jay Pasachoff:
http://www.solarcorona.net/solarlinks 
Xavier Jubier: Interactive Google Maps eclipse maps: http://xjubier.free.fr/en/site_pages/SolarEclipsesGoogleMaps.html 
Xavier Jubier: Interactive Google Earth eclipse: maps:http://xjubier.free.fr/en/site_pages/SolarEclipsesGoogleEarth.html 
Magda Stavinschi: Small Dictionary of Eclipses: http://www.tug.tubitak.gov.tr/tutulma/dictionary/eclipse_dictionary.pdf 
2009 China eclipse site at Tianhuangping (US-China-India-Greece-Russia-Georgia-Bulgaria/IAU)

http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2009_GM_WilliamsCollege.html 

4 simultaneous movies from Williams College 2008 eclipse site in Siberia

4 simultaneous movies from Williams College 2008 eclipse site in Siberia

4 simultaneous movies from Williams College 2009 eclipse site in China

4 simultaneous movies from Williams College 2009 eclipse site in China

References

Fred Espenak and Jean Meeus: Five Millennium Canon of Solar Eclipses: –1999 to +3000 (2000 BCE to 3000 CAE): http://eclipse.gsfc.nasa.gov/SEpubs/5MCSE.html 

Fred Espenak and Jay Anderson: Total Solar Eclipse of 2008 August 01, NASA Technical Publication TP-2007-214149, 2007. http://eclipse.gsfc.nasa.gov/SEpubs/20080801/rp.html 

Fred Espenak and Jay Anderson: Total Solar Eclipse of 2009 July 22, NASA Technical Publication, 2008. http://eclipse.gsfc.nasa.gov/SEpubs/20090722/rp.html 

Fred Espenak: Fifty Year Canon of Solar Eclipses: 1986 - 2035 (Sky Publishing Corporation). http://eclipse.gsfc.nasa.gov/SEpubs/RP1178.html 

Fred Espenak: Fifty Year Canon of Lunar Eclipses: 1986 - 2035 (Sky Publishing Corporation). http://eclipse.gsfc.nasa.gov/SEpubs/RP1216.html 

Fred Espenak and Jean Meeus: Five Millennium Canon of Solar Eclipses: –1999 to +3000 (2000 BCE to 3000 CAE): http://eclipse.gsfc.nasa.gov/SEpubs/5MCSE.html 

Leon Golub and Jay M. Pasachoff: Nearest Star: The Surprising Science of Our Sun (Cambridge, Mass.: Harvard University Press, 2001). http://www.williams.edu/astronomy/neareststar 

Leon Golub and Jay M. Pasachoff: The Solar Corona (New York and Cambridge, U.K.: Cambridge University Press, 1997). www.williams.edu/astronomy/corona.  The second edition is in press for publication in late 2009.

Pierre Guillermier and Serge Koutchmy: Total Eclipses: Science, Observations, Myths and Legends (UK: Springer Praxis), 1999; translated from the French.

Philip S. Harrington: Eclipse! The What, Where, When, Why & How Guide to Watching Solar and Lunar Eclipses (New York: Wiley), 1997.

Wolfgang Held: Eclipses 2005—2017 (Edinburgh, Scotland: Floris Books); translated from the German.

Mark Littmann, Fred Espenak, and Ken Willcox: Totality: Eclipses of the Sun (New York and Oxford: Oxford University Press, 3rd ed., 2008).

Michael Maunder and Patrick Moore: The Sun in Eclipse (New York, Heidelberg, and Berlin: Springer, 1998).

Martin Mobberley: Total Solar Eclipses and How to Observe Them (New York: Springer, 2007).

Guy Ottewell: The Under-Standing of Eclipses (Greenville, SC: Astronomical Workshop, 1991).

Jay M. Pasachoff and Michael A. Covington: The Cambridge Eclipse Photography Guide (New York and Cambridge, UK: Cambridge University Press, 1993).

Jay M. Pasachoff: A Field Guide to the Stars and Planets, 4th ed. (Boston: Houghton Mifflin Co., updated 2006). http://www.williams.edu/astronomy/fieldguide 

Jay M. Pasachoff: The Complete Idiot's Guide to the Sun (Indianapolis: Alpha Books), 2003.  http://www.williams.edu/astronomy/sun .  The entire book is online.
http://books.google.com/books?id=uB_l_OgKf3kC 

Jay M. Pasachoff and Alex Filippenko: The Cosmos: Astronomy in the New Millennium (Belmont, California: Cengage), 2007. http://www.solarcorona.net 

Jay M. Pasachoff, "Scientific Observations at Total Solar Eclipses," Research in Astronomy and Astrophysics 9, 613-634, 2009,

                 http://www.raa-journal.org/raa/index.php/raa/article/view/182

Duncan Steel:  Eclipse: The celestial phenomenon that changed the course of history (Joseph Henry Press, Washington, DC), 2001.

F. Richard Stephenson: Historical Eclipses and the Earth's Rotation (Cambridge, UK: Cambridge University Press), 1997.
http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=9780521461948 

Jack Zirker: Total Eclipses of the Sun (Princeton, NJ: Princeton University Press), 1995.
http://press.princeton.edu/titles/5636.html 

Jack Zirker: Journey From the Center of the Sun (Princeton, NJ: Princeton University Press), 2004.
http://press.princeton.edu/titles/7127.html