Volume XVIII No. 7 April 2007 gggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg Gem in the Woods by Karl Hricko If you haven't heard about it already, there's a dark sky site in northwestern New Jersey, from where you can actually see the Milky Way. It's located at Latitude 40° 54' 26.8" North, Longitude 74° 55' 31.8" West, and 1100 feet above sea level in Jenny Jump State Forest, near Hope, New Jersey, in Warren County. The site is one of the few dark sky locations left in the state. At this site, is a facility which is maintained and operated by the United Astronomy Clubs of New Jer-sey (UACNJ). It has a 16-inch Newtonian telescope in its Greenwood Observatory and it maintains an edu-cation center with a lecture hall and a modest New Jersey astronomy museum. It has a research library, sleeping accommodations, meeting room, full bath, and kitchen facilities available for its member observ-ers. The UACNJ leases the property from the New Jersey Department of Environmental Protection. The UACNJ was formed in 1988 as a loosely associated umbrella networking group for New Jersey area amateur astronomy clubs. It's not a club, but a consortium of a dozen and a half clubs, united to bet-ter help support, coordinate, and communicate ideas among over 1400 individuals who make astronomy their hobby, in and around the state. To offer something special to our member clubs, the UACNJ maintains a Speakers' Bureau, and it awards Messier, Asteroid, and Spectroscopic Certifi-cates to qualifying observers, (these are in the proc-ess of being rejuvenated). UACNJ maintains a web-site at www.uacnj.org which provides information on member clubs and provides links directly to all their web sites. Three member clubs (Amateur Astronomers Inc., Skyland Star Gazers of East Hanover, and the Ama-teur Astronomers Association of Princeton, Inc.) already have operational observatories on the UACNJ site at Jenny Jump. Under construction are two other observatories. One will be maintained as a solar ob-servatory, while the other will be available for doing research. Another observatory is in the planning stage and will house a donated 0.7-meter Newtonian-Nasmuth Cassegrain instrument. A radio telescope will also be available very shortly, along with the Tuthill 20-inch Trailer Telescope (currently being restored by members of AAI). Another major function of UACNJ is to promote public awareness of astronomy through use of our (continued page 3: Gem) Deep Sky Divide by Gordon Bond Astronomy books and magazines lie. Well, ok, maybe that's too strong an indictment. But they do mislead. Anyone who has put eye to eyepiece knows that the reality is never quite what they show in those stunning pictures that we all we 'ooh' and 'ahhh' over. More often than not, it falls extremely short. A long time ago, when I still had the time to be a rabid deep sky observer, I came to the conclusion that there's a rather critical moment when you run headlong into that disappointing disparity. It's the difference between being an amateur astronomer or following some other hobby. But even if you do still succumb to the former's calling, it can still be the difference between becoming a deep sky observer or a lunar/planetary aficionado. The Moon and many of the planets, on a good night, can illicit the same kinds of 'oohs' and 'ahhhs' as their pictures. Saturn is pretty darn neat even at low powers. Mars can be capricious, but in those moments when the features pop out, it can be inspiring. Plus, they change, as anyone who has followed the festoons of Jupiter can attest. Even the Moon, though somewhat stagnant itself, shows both subtly and breathtakingly dramatic differences in aspect, all depending on the lighting. By contrast, deep sky objects just sit there - the odd supernova spicing up a galaxy aside. And, with the exception of a handful of showpiece objects, they always fall exponentially short of their presence on film or a CCD chip. So why do deep sky folks overcome the initial disappointment and continue to chase the proverbial "faint-n- fuzzies"? The act of observing exists on two fundamental planes. On the one is the ascetic - the sheer enjoyment of something beautiful. The Orion Nebula can live up to its image if you have a dark enough sky, a big enough aperture and a few nebular filters. Indeed, it's possible to see details with the eye that are washed out in photographs or CCD images. The bigger globular clusters like M13 in Hercules glitter as if they were alive. The Ring Nebula is clearly a ring and the Andromeda Galaxy is neat even naked eye under a dark sky. This is that 'ooh' and 'ahh' factor and it's pretty universal (no pun intended!). Even folks who know nothing of astronomy or telescopes appreciate it. This is what the books and magazines use to hook the potential buyer. The other is the intellectual plane. Imagine spending hours in the cold, your back aching from trying to hold the same position at the eyepiece, trying des-perately to determine if that hint of light you thought you saw with averted vision is really NGC-whatever or just a case of wishful seeing. There's no big payoff. No spectacular vistas. No 'ooh' and or 'ahh.' So why bother? The perverse charm of this kind of observing is in the intellectual curiosity that the mere breath of light you can barely snatch a glimpse of is, in fact, a galaxy - billions of stars so far away that their sum- total barely registers on your retina. Yet, for those scant moments, those few stray photons ended their billions-of-miles journey by being absorbed, processed and appreciated by a human in their backyard. Either that enchants you or it doesn't. Back in the day, I was indeed enchanted by it. I still am, even if I only have time to write about it now and reminisce. The thrill was in the hunt - just not in the brutal find-something-magnificent-and-kill-it mentality. The thrill is in the challenge - of bringing every bit of brute force aperture you can afford, every technological 'cheat' of filters and eyepieces in your accessory case, every subtle art of averted vision, all your patience for that one moment when the seeing is perfect, all to bear on cajoling one more smudge of light out of the sky. Deep sky observers are a bit like collectors of anything rare or precious. Diehards seek to push their own personal envelopes to add another score to their list; another checkmark in the catalogs. In the late 1980s and early 1990s, some observers, such as Steve Gottlieb, Jack Marling, Alister Ling, Alan Goldstein, etc. - legends to the rest of us - even mined the professional journals and catalogs in the quest to be the very first humans to visually record obscure objects. Most professional discoveries were made by examining photographic plates or CCD images. This was in the days before the widespread availability of information via the internet or public domain catalogs on CDs. Field time was augmented by trips to university libraries and pumping quarters into the copy machines. That was how I hunted down the obscure planetary nebula in Hercules called DDDM-1. Also known as DdDm-1 after its discoverers, Doldize and Dzimselejsvili, there was never a DDDM-2! Not that it was particularly difficult to locate or pick out with an O[III] filter, mind you. Enter "DDDM-1" into Google and lots of subsequent observations by both professionals and amateurs come up (some 45,200 hits, most of which seem to be about this object, though I haven't looked at all of 'em!). But the point is that while not exactly a showpiece object (it just looks like a star that blinks on and off with and without the (Continued page 6: Divide) Gem (Continued from page 1) telescopes, presentations, and interactive museum displays. As part of this mission, UACNJ closely collaborates with Jenny Jump State Park so that we are considered to be part of their activities. Our astron- omy programs are available to the public on Saturday evenings from April through October, from 8:00 to 10:30 p.m. It includes a lecture from 8:00 to 9:00 pm, followed by an observing session until 10:300 pm. Other public activities include special presentations made on Astronomy Day, (this year on April 21), and at our UACNJ Symposium (September 15 in 2007). Club Membership in the UACNJ may be made by any New Jersey astronomy club (or a club from a bordering state whose membership includes New Jersey residents) if it has been in existence for at least one year. Club Membership is $25 per year per club. FOCUS, the UACNJ newsletter, is mailed to each club representative in hopes that it will be reproduced with the local club's newsletter. A copy of the speakers bureau is distributed regularly to each club. Club Supporting Membership for the Observatory at Jenny Jump is an additional $1 per member per year ($10 min.). Supporting clubs may hold regular club star parties at Jenny Jump. Observership at Jenny Jump is open to any individual who is a member in good standing of a UACNJ member club. The annual dues are $20 for members from UACNJ supporting clubs (AAI is a supporting club, therefore, their members qualify for this rate), and $25 from members of non-supporting clubs. What's also required are two nights of public duty per year. Sustaining Observership is $50. Observers have access to the observatory (and sleeping accommodations) at any time to observe or do research. The C-14 Schmidt-Cassegrain telescope mount in the AAI observatory at Jenny Jump is about to undergo a significant upgrade. See Al Witzgall about checkout on its operation. AAI members can thus enjoy a significant added benefit of membership. To find out more about UACNJ, go to our website at www.uacnj.org You can also use an interactive map ( at http://tinyurl.com/2j8lke ) that can be moved and zoomed. The map can also give you driving directions from any starting point. So if you're looking for a convenient dark sky site, and want to promote astronomy throughout New Jersey, consider becoming a member observer of the UACNJ at Jenny Jump State Park. It will give you an opportunity to enjoy the night skies, and to help others in realizing the joy of astronomy. Stewart's Skybox By Stewart Meyers Inspired by the recent total lunar eclipse, that beautiful image of the Moon transiting the Sun as seen by one of the STEREO spacecraft provided by Ken Kremer for the photographic supplement to last month's online edition of the Asterism, and the recent appearance in the area by Dr. Fred Espenak (America's foremost eclipse expert), I have decided to devote this column to discussing eclipses. As almost everybody knows, there are two basic types of eclipses: solar and lunar. I am also sure that just about everyone knows the difference between the two - the Moon passes in front of the Sun in a so-lar eclipse while the Earth gets in between the Sun and the Moon during a lunar eclipse. Astronomical Prehistory Tour In ancient times, eclipses were mysterious spec- tacles. Solar eclipses were probably quite terrifying since it appeared that something was trying to eat or at least attack the Sun. Lunar eclipses were a bit less frightening, but the sight of the bright full Moon dim-ming and changing color must have been unsettling and was thought of as a bad omen. At some point, a few thousand years ago (no one is certain as to when or where), people figured out the basics of what was happening, and eventually that these events could be predicted. According to Fred Espenak, it was most likely that lunar eclipses were predicted first. This was because lunar eclipses are easier to observe and that many societies kept track of motion and phase of the Moon. Stonehenge and several other Neolithic structures in Britain are thought to have alignments with the rising and setting points of the Moon. Lunar alignments have been also claimed for a mound complex con-structed by the Hopewell tribe near Newark, Ohio. From such observations, it was deduced that eclipses repeated over a period of 18 years and 11 days. This is called the Saros cycle, though it seems that the concept was first recorded by the early societies in Mesopotamia (modern day Iraq). Solar eclipse prediction came a little bit later, and the first written account of a predicted solar eclipse was when Greek scientist, Thales, predicted a solar eclipse for May 28, 585 BC. However, it is likely that the Chinese could also predict eclipses around this time as shown by the story (probably apocryphal) of two Chinese court astrologers who got drunk one night and were so hung over that they were unable to do their duty of eclipse prediction. They were axed - literally - when the emperor found out. Dark Side of The Moon Now we discuss the eclipses themselves. Solar eclipses come in three varieties - total, partial, and annular. A total eclipse is when the Moon appears to completely cover the Sun. Partial eclipses are ones where only some portion of the Sun is covered, and annular eclipses occur when the Moon is just a little too small to cover the Sun, leaving a ring of solar sur-face exposed. The fact that we have these eclipses is due to coincidence. The Sun is about 400 times lar-ger than the Moon, but it is also about 400 times fur-ther away. Still, the Moon is a little too small. But when it is at or near perigee, the reduced distance increases the apparent size enough to do the job. Since the Moon is gradually receding from the Earth, this situation was not always the same and it will change in the far future. Up until about 600 million years ago, annular eclipses were impossible since the Moon was close enough to the Earth that it never appeared too small to completely cover the Sun. And in about 500 million years, there will be no more total solar eclipses as the Moon will no longer appear large enough to cover the Sun completely. Despite the fact that solar eclipses slightly out-number the lunar eclipses, they are observed less frequently. This is because of geometry. Since the Moon is quite a bit smaller than the Earth and some distance away, it forms a two-part shadow, as seen in this diagram. If an observer is in an area crossed by the penumbra but not the umbra, they see a partial eclipse. People in the path swept out by the umbra see a total eclipse. Sometimes, the umbra misses the Earth completely and all one can see is the partial. In the case of an annular eclipse, the umbral shadow reaches a point above the Earth's surface. This is why we see a ring of sunlight in those eclipses. There is also a rare type of eclipse called a hybrid, which can be annular or total depending on location. (Continued Appendix page 1: Skybox) Ed Note: The conclusion of this article will be pub-lished in the May edition of the Asterism. However, it is immediately available as an appendix to the online ver-sion. Visit the AAI website at www.asterism.org and click "Newsletter". A Brief Discussion Of Comets by Dr. Lew Thomas The most recent comets easily seen with the naked eye in our local region were Comet Hyakataki in 1996 and Hale-Bopp a few years later. What are these visitors from space, why are they called comets, what are they made of, what determines their brightness, where do they come from, how can they be destroyed, how are they named? Despite their extremely low mass, comets are perhaps the most spectacular objects in the solar sys-tem. Made of ices and rock, periodic comets move along elliptical orbits that often pass beyond Neptune and Pluto. Some comets have open orbits which are parabolic or hyperbolic. These latter ones never return. Comets become visible to earth observers generally when they cross the orbit of Mars. In this region, the increase in temperature causes the ices in comets to begin to sublime. At first, a coma is formed around the head of the comet. Then, as the comet passes toward the inner solar system, gases released from the head form a tenuous tail that can stretch for millions of miles beyond the head. The tail often is of two parts; a gas tail and a dust tail. The gas tail, being composed of less massive particles, is ejected from the head at a higher velocity than the dust tail. Since the comet is moving in a curved path, the lower velocity dust tail curves away from the gas tail which remains relatively straight. Both tails point away from the Sun. Sometimes a jet of gas ejected from the comet's head can point toward the Sun. Cometary orbits may be elliptical as with periodic comets, or parabolic or hyperbolic. The latter two cases represent a one time appearance of a comet within the Solar System. The word comet comes from the Greek and means "hairy star". This is a good description of the naked eye comets which often have long tails. Spectra of comets have indicated emission lines of molecules and radicals such as carbon (C2), cyanogen (CN), and hydroxyl (OH). These come from the break up of parent molecules such as water (H2O), carbon monoxide (CO), methane (CH4), ammonia (NH3), and more complex molecules of H2CO2, H2CO, CO2, and HCN. Much has been learned about comets by Soviet, Japanese, and European space probes sent to Comet Halley and the United States probe to Comet Giacobini-Zinner. The tail usually grows longer and brighter as the comet approaches the Sun. The emitted light is partly reflected sunlight and partly a secondary emission of the gasses receiving solar radiation energy. The brightness (B) of a comet, unless very close to the Sun, usually varies as follows B varies as 1/r2d2 (1) where r = the distance of the comet from the Sun d = its distance from Earth. The above formula applies to reflected sunlight only. As the comet nears the Sun, it generally brightens faster than (1) because of secondary emission. Also dust around a comet can decrease its brightness. Until recently, it was believed that comets originated in a cloud of gas, dust, and rock left over after the formation of the solar system, called the Oort cloud. This is thought to be located about 50,000 Astronomical Units from the Sun. The 50,000 A.U. distance is derived from the aphelia of some comets which are in that range. There is no observational evidence of the existence of the Oort cloud. Recent analyses of cometary rocks has revealed igneous material indicating that some comets have been subjected to heating and may have come from regions close to the Sun. The Kuiper belt, which is beyond Pluto but closer than the Oort cloud, it thought to contain about 1013 particles, invisible by current technology. Gravitational theory suggests that the Kuiper belt is disc shaped. Judging from the density of the nucleus of Halley's Comet, the total mass of such a large number of particles, if they exist, is about 1,000 Earth masses -- more than all the planets combined! Their effect upon the orbits of Pluto and Neptune would then be considerable but, if their distribution is random, perhaps such perturbations could not be easily measured. Every time a comet passes perihelion, it losses some of its mass because of the tidal force of the Sun. This is particularly true of comets which pass very close to the Sun. The lifetime of a comet ap- pears to vary inversely with its perihelion distance. Past records actually show the break-up of comets. Biela's comet which had a period of 6.5 years, had been observed on several occasions prior to its ap-pearance in 1845. It was then observed to become elongated and divide into two parts. Each part developed a nucleus and a tail, and both were observed for several months. On its return in 1852, the twin parts had separated by about 1.5 million miles. They have (Continued page 6: Comets) Comets (Continued from page 5) never been observed since. Unfortunately, a simple explanation like the perturbation of Jupiter, which is much too small, cannot explain this mystery. Taylor's Comet (1916 I) with a period like Biela's also divided into two parts. Sometimes a comet may crash into a planet as occurred with Comet Shoemaker-Levy 9 which hit Jupiter. This is the only cometary crash ever observed and it is thought to be rare. By the way, if you are the first to discover a comet, your name will be assigned to it. If more than one person discovers the same comet, a double name results. So if you want to preserve your name for the future, start looking! Divide (continued from page 2) filter), the pride in being able to say that I saw it is rooted firmly in that intellectual plane. So when I see someone from the general public eyeing the stunning images in the books at the sales desk at Sperry, I wonder if they will someday realize that beauty in as-tronomy is sometimes only as deep as the paper the image is printed on. And if they'll continue on past that, deeper both into the sky and themselves. MEMBERSHIP DUES Regular Membership: $21 Sustaining Membership: $31 Sponsoring Membership: $46 Family Membership: $5 Sky & Telescope: $32.95 Astronomy subscription: $34 First Time Application Fee: $3 Dues can be paid in person to Mem-bership Chair or Treasurer, or by mail to: AAI, PO Box 111, Garwood, NJ 07027-0111 DR. LEW'S SEMINARS Some of the topics for upcoming seminars include: " Things to record during solar and lunar eclipses " Defining celestial coordinates and explaining their use " Ways to enhance your tele-scope viewing (Choice of topic at Dr. Lew's seminars is determined by participants' interest) FRIDAYS AT SPERRY April 27, 2007 2007 Radical Climate Changes, The Past, Present and Possible Future Anthony Espinoza May 4, 2007 Optics 3: Linear and Circular Polarization, Filters, H- Alpha Filter Dr. Lew Thomas May 11, 2007 You Don't Have to be Rem-brandt: Drawing the Deep Sky Gordon Bond DOME DUTY SCHEDULE May 4 Team C May 11 Team D May 18 Team E May 25 Team A June 1 Team B June 8 Team C SPECIAL THANKS Ink-saving Logo for Asterism credit: Justin Shapp EMAIL CONTACTS editor@asterism.org Editor of The Asterism Ray Shapp, Acting Editor Deadline for submissions to each month's newsletter is the first Friday of that month. membership@asterism.org AAI Membership Chair trustees@asterism.org All three Trustees of AAI ray@asterism.org Ray Shapp for the website exec2@asterism.org (this is a temporary address) Executive Committee All schedules above were accurate at time of publication. Please check www.asterism.org for latest informa-tion (click on "Club Activities") Stunning Beauties of Our Solar System by Ken Kremer High Drama at Hillary Uncover more beauties of the Solar System in the pictorial supplement at www.asterism.org Click Newsletter. Please contact me for further information or public outreach presentations. My next public talk is: The Explorers Club, NY, NY, Mon Apr 23, 7 PM. "Exploring Mars, the Search for Life and a Journey in 3-D". http://www.explorers.org/index.php and http://www.explorers.org/calendar/view_entry.php?id=9317&date=20070423&user=nyc Dr. Ken Kremer NASA JPL Solar System Ambassador Email: kremerken@yahoo.com Theater In The Sky by Ron Ruemmler May 2007 belongs to the inner planets. Mercury and Venus are both beginning periods of exceptional at-tractiveness enhanced by two lovely conjunctions with the evening crescent Moon. Mercury starts the month by passing behind the Sun, but it quickly jumps high into the evening twilight. When Mercury performs this trick, it usually means just a week or two of good visibility, but this time, the little planet stays up an hour or more after sunset for a full five weeks. During the last week of May, Mercury does not set until one hour and fifty minutes after the Sun; nearly the maximum possible. On the 17th, the 29-hour-old crescent Moon passes only three degrees above Mercury, far to the lower right of brilliant Venus. Maximum northern latitude and maximum illuminated area for Mercury occur near this time, while maxi-mum elongation from the Sun has to wait until June. Unlike Venus, Mercury is at its brightest as an evening object well before maximum elongation. That's because too much of the dark half of the planet turns toward the Earth by the time of the maximum angular distance from the Sun. Of course, the apparent diameter of Mercury is increasing as it moves toward the Earth, but this is not nearly enough to overcome the dimming caused by the phase effect. Venus, on the other hand, gains so much apparent diameter that its evening elongation is just the begin-ning of the real excitement. The planet's extreme northern latitude this month combined with Daylight Saving Time makes a midnight viewing of Venus almost possible. From New Jersey, the planet sets at 11:45 PM around the 22nd. In any case, be sure to catch the spectacular conjunction of Venus with the three-day-old Moon on the 19th. We have the best time zone in the world for this event. Venus is so far north of our equator this month (26.0 degrees), that it actually passes directly over Holly-wood, FL and Brownsville, TX in the late afternoon. These events should be visible with binoculars and, possibly, even naked eye! Saturn is 90 degrees from the Sun in May. This is when the planet and its rings cast the maximum shad-ows on each other giving the most three dimensional appearance in a telescope. Jupiter now rises well be-fore Venus sets, so the sky never lacks a bright planet. Mars is still rising about two hours before the Sun as it has for the last five months. We have two Full Moons this month in the Americas, but the rest of the world will have to wait until next month for their "Blue Moon". May SKY CALENDAR 2 Wed 6:10 AM First Full Moon 3 Thu 12:00 AM Mercury passes beyond the Sun into the evening sky 9 Wed 7:00 AM Saturn at east quadrature; 90 de-grees from the Sun 10 Thu 12:27 AM Last Quarter Moon 10 Thu 12:00 PM Venus at maximum northern decli-nation (latitude) 12 Sat 8:00 PM Maximum illuminated area for Mer-cury 16 Wed 3:28 PM New Moon 17 Thu 9:00 PM Very thin crescent Moon upper right of Mercury 18 Fri 9:00 PM Mercury at maximum northern decli-nation (latitude) 19 Sat 10:30 PM Crescent Moon just upper right of Venus 23 Wed 5:02 PM First Quarter Moon 31 Thu 9:04 PM Second Full Moon 31 Thu 9:30 PM Venus-Pollux-Castor in equal spaced horizontal alignment Stunning Beauties of Our Solar System by Ken Kremer Pictorial Supplement In this golden age of space exploration, spacecraft sent aloft by Earthlings continued to unlock the myster-ies of our solar system. The arrival of Martian spring has boosted power to the rovers, Spirit and Opportunity, as one prepares to scale an eroded volcano and the other may soon plunge into a giant crater. Cassini is nearing three years at Saturn and New Horizons flies down the Jovian magnetotail. Here for your enjoyment is this month's small sampling of beauties, rich in visual beauty and previously undiscovered science that caught my attention from NASA, ESA, and JAXA in my role as a NASA Solar System Ambassador. Mysterious Hexagon at Saturn Credit: NASA/JPL/University of Arizona http://www.jpl.nasa.gov/news/news.cfm?release=2007-034 Please contact me for further information or public outreach presentations. My next public talk is: The Explorers Club, NY, NY, Mon Apr 23, 7 PM. "Exploring Mars, the Search for Life and a Journey in 3-D". http://www.explorers.org/index.php and http://www.explorers.org/calendar/view_entry.php?id=9317&date=20070423&user=nyc Dr. Ken Kremer NASA JPL Solar System Ambassador Email: kremerken@yahoo.com Skybox (Continued from page 4) Eclipses: Not Just For Looking At Starting in the 18th century, as transportation, equipment, and astronomical theory improved, a number of scientific discoveries resulted from studying solar eclipses. In 1715, Edmund Halley published broadsheets describing an upcoming total eclipse over England and its predicted path. The public was urged to report their location and what they saw during the eclipse. Using these reports, Halley not only helped confirm Newton's laws, but also discovered that the Earth's rotation was slowing down due to the tidal effects the Moon had on Earth. To this day, astronomers use old eclipse reports to track this slow change. Another solar eclipse of scientific importance was one seen in 1868 from the city of Guntur, India. View-ing that eclipse was French astronomer Pierre Janssen. During totality, Janssen used a spectroscope to study the corona and wound up making some discoveries. First, he identified a layer of the Sun called the chromosphere, which was responsible for many of the spectral lines in the solar spectrum. He was also able to determine that prominences, which resemble red or pink tufts of material sticking out of the eclipsed Sun were actually enormous plumes of hydrogen gas. Years later, it would be found that they are formed when gas follows magnetic field lines on the Sun. While looking at the corona, Janssen also came across some lines in the spectrum that no one had ever seen before. This was the discovery of helium, which got its name due to being discovered on the Sun. It would not be found on Earth until 1895. Starting with an eclipse visible in North America in 1869, astronomers noticed more odd lines in the cor-onal spectrum. Remembering Janssen, some scien-tists thought they found yet another element, which they named "coronium". However, this was not the case. In 1939, Belgian astronomer Bengt Edlen found that the lines were in fact from atoms of iron and other known elements that were subjected to such extreme temperature that they lost a number of their outermost electrons. So, instead of a new element, the lines told of the extremely high temperatures in the corona. With that mystery solved, a new one arose. The Sun's photosphere (its "surface") has a temperature of about 5,200 degrees Kelvin (K) which is about 9,000 degrees F. Yet, the corona has a temperature of over one million degrees K. Even today, no one knows the exactly why the corona is so hot, though it is thought that magnetic fields play a role. Then there was the most famous eclipse experiment of them all. In 1919, Sir Arthur Eddington, at a total eclipse on the island of Principe, photographed stars of the Hyades cluster near the eclipsed Sun. Comparing the star positions on the photographs with ones measured when the Hyades were in the night sky, Eddington found that starlight was deflected by the amount predicted by Albert Einstein in 1915 in the general theory of relativity. In 1930, Bernard Lyot invented the coronagraph, a special kind of telescope, which uses a disk and internal baffles to block the solar disk to allow the co-rona to be observed at any time. While this would seem to make scientific observations of actual eclipses unnecessary, that is not so. Coronagraphs, even those on satellites, cannot observe the innermost parts of the corona. The full corona can be seen during eclipses. So even in this day and age, solar eclipses are scientifically useful. AAI's Contribution Today, traveling to see solar eclipses is a full- fledged business. But how many of you know that the field of modern eclipse tourism was pioneered by a member of AAI? In the early 1970's, the late Roger W. Tuthill started organizing eclipse trips, including one in 1973 to the North African nation of Mauritania. The trip was a success and Roger even got a medal from the president of Mauritania. So when people discuss eclipse tours, remember that AAI was one of the first in the field. The Shadow Knows Lunar eclipses are the nocturnal siblings of solar eclipses. These eclipses are seen far more frequently, and again, the reason is geometry. This time, it is the Earth that casts the shadow. As seen from the Moon, the Earth is over four times the apparent size of the Sun. Also, the shadows are much bigger. Therefore, any location where the Moon is above the horizon at eclipse time gets to see at least some of the eclipse. The main area of scientific interest in lunar eclipses is study of the Earth's atmosphere. When a total lunar eclipse takes place, some light does reach the Moon because it is refracted by the Earth's atmosphere. Essentially, the light is from every sunrise and sunset on Earth all at once. It was reasoned back in the 18th century that the variations in color from eclipse to eclipse were due to changes in the Earth's atmosphere. If a major volcano erupts, the ash spewed into the atmosphere creates a very dark brown eclipse like the ones in 1982. If the air is devoid of large amounts of dust, the eclipse is brighter and tending towards red or orange color. One area of lunar eclipse science where amateurs have contributed is in making crater timings. This is simply timing when a crater is bisected by the umbral shadow, first when the umbra approaches the crater, and then when it leaves. The timings then yield how much bigger the Earth's shadow is than it would be for an airless Earth. According to a theory put forth by Erich Karkoschka (University of Arizona) in an article in the September 1996 issue of Sky & Telescope, the shadow enlargement is at least partly affected by the amount of stratospheric ozone. The more ozone, the larger the shadow is. If this is correct, the historical record of shadow timings offers a way of tracking ozone in the days before satellite data. But others, such as Paul Marmet and Christine Couture of the University of Ottawa, contend that the shadow enlargement is just an optical illusion. Their paper can be read at (http://www.newtonphysics.on.ca/Astronomy/Astronomy.html). Though they may be less spectacular than the so-lar variety, lunar eclipses have some scientific value. The Future The next solar eclipses will be on August 1, 2008 (Russia and China) and July 22, 2009 (China). The United States, has to wait until May 20, 2012 to see an annular eclipse and August 21, 2017 for a total. As for lunar eclipses, the next one visible (at least partly) from New Jersey will be on August 28, 2007, but will take place in the predawn sky with the Moon setting before the end of the eclipse. The total lunar eclipse after that, on February 21, 2008 will be visible in its entirety from New Jersey. Details on these eclipses can be found on Fred Espenak's NASA site at (http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html). Also, check out his personal website at (http://www.mreclipse.com/MrEclipse.html) which has lots of info as well. Now, if only we could predict eclipse weather as accurately…