Volume XVIII No. 9 June 2007 gggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg Mission Strategy For Stellafane by Bonnie B. Witzgall and Alan P. Witzgall S tellafane Convention is the annual telescope maker's meeting held every year in Springfield, Vermont. Managed by the Springfield Telescope Makers club, it is 100 percent full emersion of camping, eating, mirror testing, lecturing and learning about the joys and woes of telescopes and optics. Visitors from all over the planet trek to this special place. Stellafane was the very first astronomical assembly ever held and it laid the groundwork for all other astro assemblies. This year's Stellafane Convention will be the 72nd gathering in the Vermont countryside, only with an extra twist! Instead of beginning Convention at the traditional 9AM Friday morning, the Springfield Telescope Makers will open the gates at 3PM Thursday afternoon August 9th, adding extra hours to absorb this unique event. There is much history, solidarity, knowledge and en masse astronomy available here. The grounds have a huge observing field where you set up your telescope just in front of the MacGre-gor Observatory, which houses a large Schup-mann-design Telescope. At the top of Breezy Hill, are the Pink Clubhouse, the historic Porter Turret Telescope, and the site of the 'scope judg-ing contests. The huge, new Flanders Pavilion holds the tent talks and hands on telescope-making demo. Also available is hot food, a horse-shoe pitching contest, tee shirts, hats, Conven-tion postcards, and raffle ticket sales. Don't forget the infamous non commercial Swap Table and Flea Market that officially begins at 7AM Satur-day morning, but unofficially opens with flash- light toting customers at 6AM. Can one do it, see it, hear it and absorb all these wonders of Stellafane just in one whirlwind weekend... even with this year's extra night of viewing? As a Stellafane attendee for more than twenty five years, I would have to say, "it ain't easy, but it's so much fun to try." (continued page 6: Stellafane) Stewart's Skybox By Stewart Meyers A s I have mentioned on previous occasions, the mainstream media tend to suffer from some kind of bipolar disorder when it comes to astronomy and space science. The media pundits either get worked up over something of little significance or where there is little detailed information or they ignore significant news. Also, they evidently believe that jumping to conclusions based on tiny bits of evidence counts as exercise. The latest example of the mainstream media be- having badly began when of the European Southern Observatory announced that they had discovered an extrasolar planet in orbit around Gliese 581, an oth-erwise unremarkable red dwarf star about twenty light years from Earth in the constellation of Libra. The planet was the smallest extrasolar planet yet detected (as of early June 2007) with a minimum mass 5.1 times that of the Earth. It is also one of a very small number of planets that are known to orbit red dwarf stars. However, that was not what got the attention of the mainstream media. Based on the orbit and the properties of Gliese 581, the initial calculations showed that the base temperature (without taking into account any atmospheric or rotation effects) was in the range of 0 to 40 degrees Celsius (32 to 104 Fahr-enheit), which was in the range where water would remain liquid. Almost immediately, news organiza-tions and others reasoned that the planet was habitable. And some in the mainstream media thought it was another Earth, including one in the local AAI area. But this will be discussed later in the article. Now would be a good time to look at the history of extraso-lar planets. A Fried Friar The idea of other solar systems besides our own is not terribly new. The first mention of anyone conceiv-ing of other systems was back in the fourth century BC, when the Greek philosophers Democritus and later Epicurus argued that there were other inhabited worlds. It cropped up again in the works of the Ro-man philosopher-poet Lucretius in the first century BC. The next mention of the idea occurs in 1584. Evi-dently influenced by De Revolutionibus written by Nicolas Copernicus, a former monk, Giordano Bruno wrote that the stars in the night sky are suns like ours but very far away. And those stars would have plan-ets orbiting around them though they could not be seen since they did not give off their own light. Fi-nally, Bruno asserts that these planets could be in-habited like the Earth. Unlike, the atomist Greco-Roman philosophers who were merely ignored, Bruno was not. Instead, the Catholic Church took notice and was less than pleased. Eventually, Giordano Bruno wound up being burned at the stake in 1600 as a heretic. Contrary to popular belief, he was not burned for his statements about the plurality of worlds. While that was heretical, the offense that got him the death penalty was most likely his doubts about many of the tenets of Christianity. After Bruno was made a complete ash, the idea of planetary systems outside ours languished. The only noteworthy mention in the 18th century was in the story Micromegas by Voltaire where a being from a planet orbiting Sirius visits Earth to study humans. However, that story was written as social satire, not scientific extrapolation. Sirius White (Dwarf) Curiously, Sirius played a role in reviving the idea of objects orbiting other stars. Despite appearing "fixed" relative to each other, stars are actually mov-ing through space. This motion, as seen from Earth, is known as proper motion. Most stars are so far away from Earth that this motion over many years is barely perceptible to professional instruments. But, nearby stars appear to move faster. Friedrich Wilhelm Bessel was obsessed with mak-ing precise astronomical measurements. This obses-sion paid off well when, in 1838, he was able to measure the parallax of 61 Cygni and find its dis-tance. With this success under his belt, Bessel turned his attention to other nearby stars, including Sirius. While measuring the star's proper motion, Bessel no-ticed a slight wobbling. He deduced that this wobble was the result of an unseen companion object orbit-ing Sirius and tugging on it via gravity. The basic idea is illustrated in the following diagram which I created: It would not be until 1862 that this companion would be seen visually by Alvan Clark and was later found to be a white dwarf star. Jump forward to 1938. Peter Van de Kamp at Sproul Observatory (Swarthmore College) reasoned that looking for wobbles in proper motion might work to detect large planets orbiting low mass stars. What was needed was a very low mass star that was nearby and had a large proper motion. The recently discovered (1916) Barnard's star, six light years from Earth was selected, as it had an exceptionally large proper motion (it can even be detected over several years with amateur instruments). After 24 years of observation and measurements, van de Kamp an-nounced that he had found a planet orbiting the star. It was 1.7 times the mass of Jupiter and had an or-bital period of 25 years. He continued to make meas-urements, and, in 1969 claimed to have detected another planet in the system with an orbital period of about 12 years. Van de Kamp also revised the mass estimates and said that the first planet was 1.1 times the mass of Jupiter while the inner one was 0.8 times Jupiter's mass. Up until 1981, he kept revising the details of the planets, with the masses getting smaller and the orbital periods getting shorter. However, people started to have their doubts. In 1973, George Gatewood and Heinrich Eichorn ana-lyzed photographs of Barnard's Star taken with the 20-inch refractor at the Van Vleck Observatory (Wesleyan University) as well as with the 30-inch Thaw refractor of the Allegheny Observatory at Pitts-burgh. No wobble was detected in those images. And, in what was pretty much the mortal blow to the putative planets, John L. Hershey at Sproul observa-tory reanalyzed the photographs that van de Kamp used. But he also studied several other stars in the images. It turned out that they all had the same wob-ble. The variations that van de Kamp measured were due to the instrument itself, a view supported by the fact that the telescope had the lens cell replaced in 1949 and had it readjusted in 1957. To his dying day in 1995, van de Kamp never gave up his belief that he had found planets orbiting Barnard's Star, though the astronomical community did. Even with this setback, proper motion study was still considered a viable technique. As recently as February 1980, Sky and Telescope ran an article de-scribing four possible techniques to find extrasolar planets. The technique most likely to succeed was, according to the article, proper motion study. The other techniques listed, were photometric (looking for extrasolar planets passing in front of their parent star), direct imaging of extrasolar planets, and radial velocity measurements via high-resolution spectros-copy. In some ways, the article was prophetic, in oth-ers not. Of the techniques, one was a failure, two were successful, and one is at the very edge of cur-rent technology. But that is getting ahead of the story. The first extrasolar planets ever detected were found in a most unlikely place. Really Bad Neighborhoods Most AAI members know that pulsars are rapidly rotating neutron stars that emit streams of energy like beams from a lighthouse. They are also among the most precise timekeepers in nature. In 1992, Alexan-der Wolczan, while studying a pulsar over 600 light years away in Virgo, detected some unusual changes in the time of the pulses. Upon further analysis, it was found that the pulsar was orbited by an object about 3.9 times the mass of the Earth with a period of 66 days. Such an object could only be a planet. Later measurements turned up two more, one 4.3 times the mass of the Earth (orbital period of 98 days) and the other with a mass twice that of the Moon (orbital pe-riod of 25 days). How planets could have formed around a pulsar is a bit of a mystery. Two years later in 1994, Stephen Thorsett discovered a planet orbit-ing another pulsar in Scorpius with a mass of 2.5 times that of Jupiter and an orbital period of 10 years. The Floodgates Open In 1995, a pair of Swiss astronomers, Michel Mayor and Didier Queloz, realized that the astrometric method of detecting planets would require optical resolution beyond currently available equipment. But, the gravitational tug of a planet on a star would in-duce changes in the star's velocity that might be de-tectable with the high- resolution spectroscopic equipment being used to do detailed studies of stellar composition. So, the pair of astronomers compiled a list of stars similar to the Sun and started to take re-peated spectra of them, looking for small variations in the lines of the spectrum that repeated at a regular time interval. This strategy paid off with the discovery of a planet orbiting 51 Pegasi, the first planet found orbiting a normal main sequence star. Three months later, a pair of American astronomers, Geoffrey Marcy and Paul Butler would confirm the discovery. But this planet had some surprises. First of all, its mass is between half that of Jupiter to about twice Jupiter's mass. But that was nothing compared to the next surprise. The orbital period of four days meant that this planet orbited only five million miles from its parent star. According to the conventional wisdom of the time, large planets were thought to exist only in the outer regions of solar systems, much like the gas giants in our solar system do. However, the discovery was confirmed and it was thought that maybe this planet was an oddball. Eventually, other groups of astronomers got in on the act. The discoveries quickly accumulated and it turned out that many of these extrasolar planets were very large and orbited close to their stars. While it was concluded that this abundance of "hot Jupiters", as they were soon called, might have something to do with the nature of the radial velocity method (large planets orbiting close would cause greater and easier to detect variations), it was also apparent that our un-derstanding of planet formation needed revision. Cur-rent consensus is that in the early stages of planet formation, some planets can experience drag from material in the circumstellar disk that they were born in, and this drag causes the planet's orbit to migrate closer to the star. This process stops when the planet reaches an area in the disk that is either empty or is simply too thin to generate the drag. Eventually, as the length of time stars were being monitored grew longer, some planets with longer or-bital periods and at more conventional distances from their parent stars were discovered. Planetary Transit Authority Measuring spectra was not the only way to find ex-trasolar planets. One of the methods mentioned in the Sky & Telescope article, but was considered not likely to yield results, was photometric measurement of the drop in light as a planet crossed in front of a star. But, it actually yielded some discoveries. In 1999, Geof-frey Marcy was monitoring HD 209458, a star 150 light years from Earth, in Pegasus that had shown from radial velocity measurements that it might have a planet, when he detected a 1.7 percent dip in the star's light with a period that matched the planet's or-bital period (3.5 days). Today, there are 21 planets known to transit their stars, including one found by the COROT mission ( www.esa.int/SPECIALS/COROT/ ) recently launched by the European Space Agency (ESA). COROT pro-mises to find many more. As opposed to the radial velocity method which gives only the orbital period and a minimum mass (the actual mass is dependent on the tilt of the orbital plane relative to Earth), observations of extrasolar planet transits can yield far more information such as exact mass, tilt of the orbital plane, diameter, and density. For example, the planet around HD 209458 has a radius 60 percent bigger than Jupiter, but only about 63 percent of the mass. The density is 0.2 grams per cubic centimeter. More recent analysis has found evidence of a tail of gas emanating from the planet, perhaps as a result of losing atmosphere un-der the intense heat and solar wind. And there's more. It is possible, utilizing the Spitzer infrared space telescope, to obtain rough spectra of transiting extrasolar planets. This is done by compari-son of the spectrum of the combined system when the planet is next to the star and the spectrum when the planet is behind the star. The star's spectrum is subtracted and what remains is that of the extrasolar planet. This has allowed astronomers to learn the composition of the atmosphere of the planets. Using a somewhat similar technique, Harvard as-tronomers used the Spitzer space telescope to measure the variation in infrared energy on the planet orbiting HD 189733. After much work and analysis, a crude weather map was made that revealed a hot spot in the planet's atmosphere offset by about thirty degrees from the point directly under the star. More details on this and extrasolar planet spectra can be found at the Spitzer Telescope website ( http://www.spitzer.caltech.edu ). The Others Extrasolar planets have been discovered by other means as well. According to the Extrasolar Planet Encyclopedia ( http://extrasolar.eu ), four planets have been discovered via gravitational lensing. This is possible when a star and planet pass in front of a much more distant star. According to relativity, the gravity of the planet, as well as that of the star, will bend the light of the more distant star, and cause a slight brightening. By measuring the duration and magnitude of the brightening, the masses of the ob-jects can be determined. Two major drawbacks of this method are that only a mass can be determined, and it is not repeatable. Then there is direct imaging. To date, four potential planets have been imaged, mainly in the infrared. However, there is great uncertainty about their masses and some, if not all, could be brown dwarfs rather than planets. But, direct imaging will become a more effective tool with the launch of ESA's Darwin mission, which will place an array of telescopes in space to function as one large telescope, which should be able to re-solve planets in other star systems. NASA's planned Terrestrial Planet Finder (a more advanced version of the idea behind Darwin) appears to have been a casualty of budget cuts at NASA and may never be built. Worlds According To Judith While the initial discovery of the planet orbiting 51 Pegasi in 1995 caused quite a stir in the mainstream media, including an episode of the ABC news pro-gram "Nightline" discussing the search for extrasolar planets, the excitement died down as planet discover-ies became more frequent and the novelty wore off. But, that changed this past April. A team of as-tronomers at the European Southern Observatory (ESO) discovered the now-infamous planet orbiting Gliese 581, which I mentioned at the beginning of the article. Unfortunately, the astronomers involved played up the fact that the planet was rocky, was po-tentially in the habitable zone (an imaginary ring in a planetary system where planets may have tempera-tures favorable for life) and that water could exist on the surface in liquid form. At the same time, they downplayed how little was actually known for certain. The mainstream media heard only the words "wa-ter" and "habitable", and started claiming that a twin of the Earth was discovered. That was very far from the truth. If one could visit Gliese 581b, one would find that the planet had stronger gravity than the Earth (the strength would depend on the density of the planet as well as the actual mass). The planet would most likely (Continued page 10: Skybox) The Many Motions Of The Earth By Dr. Lew Thomas W e all know the Earth rotates on its axis each day and takes about 365.25 days to orbit the Sun, but these are only a few of Earth's motions. To begin with, there is precession of the Earth's spin axis. This occurs because the Earth is tipped about 23.4 degrees to the plane of its orbit and the Earth has an equatorial bulge. The Sun pulls on this bulge and, if the Earth were not spinning, it would right the axis tilt. Due to the spin, however, the Earth acts like a giant gyroscope and moves at right angles to the Sun's pull causing a long period wobble called precession. Over a span of 25,784 years, the North Celestial Pole (point directly above the Earth's north pole) describes a complete circle around the North Ecliptic Pole which is the pole of the Earth's orbit. But that's not all. The Moon also gets into he act of pulling on the Earth's bulge. This has two effects. First, it causes a nodding motion of the North Celes-tial Pole toward and away from the North Ecliptic Pole. This is called nutation. Second, it causes a pe-riodic change in the advance of the NCP around the NEP. This is called equation of the equinoxes. All in all, the Moon varies the progress of the NCP by a maximum of 9.23 seconds of arc with a period of 18.6 years. The total Sun and Moon effect is called Luni-Solar Precession. The North Ecliptic Pole also moves due to the pull of the planets which are not exactly aligned with the Earth's orbital plane. This is called Planetary Preces- sion and it is only 1/40 as large as Luni-solar Preces-sion. It moves the vernal equinox 0.11 seconds of arc each year toward the east. Luni-solar Precession moves it 50.24 seconds a year toward the west. Planetary effects also reduce the tilt of the Earth's axis by 0.47 seconds per century. Our Milky Way Galaxy is rotating, therefore, all the stars in the Sun's vicinity share this general motion of 230 km/s. But the Sun is moving 4.1 astronomical units per year faster than this average motion and it caries the Earth and all the planets with it. This differ-ence in speed is unexplained. And to top it all, our galaxy is traveling 600 km/s with respect to the microwave background radiation in the direction of right ascension 10 hours and declina-tion -20 degrees. And how our universe may be traveling with re-spect to other universes, if they exist, is beyond the scope of today's writing! Stellafane (continued from page 1) H owever, as a courtesy to those who have never been to the 'Shrine to the Stars', I offer the following personal recommendations, and Convention insights not found anywhere else. Remember AAI does not officially en-dorse any of these suggestions. For what it's worth, your results and weather conditions may vary. Please choose wisely and adapt my 'insider ideas' to your own needs. DO YOUR HOMEWORK - If you are new to this year's Stellafane Convention, you must review the STM website at www.stellafane.com It provides a good background for the club's history, how to pre-register, camping conditions and what to expect at Convention. Lecture series, workshops, telescope judging, and all hands on programs are also listed. Note the different registration and camping fees, ac-cording how and when you wish to attend Convention. You also find a list of area campgrounds, hotels and terrestrial maps to help you find Stellafane. Print these pages and study them well. Insider Information: AAI's own Clif Ashcraft is giving a lecture on web cams dur-ing the Saturday afternoon tent talks. SLEEPLESS IN SPRINGFIELD - Fagetaboutit! No sleeping allowed at Convention, period! Too much to do, see, and learn all at the same time! To solve this dilemma, cloning is recommended and transporter ac-cident replicas are tolerated. If the evening is clear with 6.5 naked eye magnitude skies, sleep is highly dis-couraged. Yet, if it rains, the rhythm of the leaking del-uge and muffled cursing will deter sleep anyway. In-sider Information: Stellafane has too many wondrous things to arouse the senses. Save your sleeping time for the cloudy nights back home. PERSONAL HYGIENE - Although water is available free at the Bunk House for conventioneers, there are no showers or flush toilets on site. Porta Johns serve the three day Convention, which are cleaned out by tanker trucks making their rounds every few hours. The trucks are adorned with the motto: "We're the Life of the Potty." Smile and wave to these imperative people. Insider Information: just in case, carry your own extra toilet paper, Wet Wipes, and anti bacterial hand gel. VITAL SUPPLIES - One can't have too much sun-screen, toilet paper, paper towels, bug repellant, red light flashlights, umbrellas, rain ponchos, first aid items, good walking shoes, mud boots, and extra socks of various thicknesses. Add to that list a lot of batteries, film and plastic garbage bags. That weekend, Vermont may experience a heat wave, unless the cold wind blows a heavy thunderstorm across the gloomy observing field. In-sider Information: bring a great assortment of plastic bags and tarps of all sizes. They convert into universal dew covers, sunshades, dirty clothes sacks, trash bags and rain shields for scopes, tents, laptops and people. ASTRONOMICAL FASHION - Dress for survival! For the hot daytime, wear short sleeves, a hat, sunglasses, solar filters, shorts, backpack to carry water and cam-era… unless it rains. For the evening, bring a winter jacket, gloves, scarf, wool cap, thick socks and ther- mos for hot coffee to fend off the chilly night… unless it rains. Bring clean clothing for walking around town, leaving your mud caked jeans, dusty shirts and soggy shoes somewhere else. Insider Information: realize you are not a slave to ritzy fashion because all as-tronomers look alike in the dark. BASE CAMP - By now, all the local Vermont camp-grounds, that have shower facilities, are booked with Stellafane conventioneers. People made reservations during the 2006 Convention for this year's event. If you pre register for a campsite at Stellafane, you'll be guaranteed a place, but not on any specific site. The place to pitch your tent is directly related to your point of interest. Want to be near the tent talks, the observ-ing field or the Swap Table? Need constant use of the Porta John, or want to rest under shady trees or need to cozy up to the person who has the big generator and working laptop? That determines your camping loca-tion. Get there early for the best pick. Allow time for tent pitching, but expect the neighboring campers to lend a hand. Insider Information: don't put your tent in a low dusty spot, because a bad rainstorm could wash you away to the Black River. ON SITE TRANSPORTATION - Two yellow school buses, hired by the Springfield Telescope Makers pro-vide cheap transport throughout Convention. For just $1.00, one can commute around the entire grounds, including a trip up the hill to the Clubhouse and Turret Telescope. Otherwise, bring comfortable shoes and sandals. If nothing else, Stellafane provides many op-portunities for physical exercise and heat exhaustion. Insider Information: for tradition sake, walk Breezy Hill to the Pink Clubhouse just once, and then take the bus. On a hot Summer afternoon, the bouncy bus ride is worth the trip. LOCAL RESOURCES - Downtown Springfield is only three miles from Convention. In the heart of the city, you will find the Springfield Plaza, home to Shaw's (a super food store), Friendly's Ice Cream, a discount close out store, a local bank and Aubuchon (an old fashioned hardware store). Across from the Plaza is the venerable McDonalds and a gas station with a clean convenience store that sells Vermont mountain coffee and VT souvenirs. Insider Information: on the way to Convention as you continue along Route 11, you turn right at the hospital's blinking light, and look on your right for an indoor farmers' market selling fresh local produce. CONVENTION FOOD TENT - Each year, an excel-lent food concession erects a giant tent to serve the 3000+ attendees, complete with red lighting, respecting everyone's night vision. Breakfast, lunch and dinner are available along with the traditional Roast Chicken Dinner offered on Saturday evening. It's interesting to watch the hundreds of chicken pieces cooking on huge BBQ grills. During past Conventions, if night sky condi-tions remained clear, all beverages, salads, snacks, fruit, and spare burgers were available until the kitchen closed at 2AM to accommodate the hectic observers. Insider Information: the Roast Chicken dinners offer two large pieces of chicken, fresh Vermont corn on the cob, one side, salad, strawberry shortcake and beverage of choice. One dinner is enough to share for two average eaters. Because the crowds are so large under the massive food tent, you may be wise to bring your own chairs and eat Saturday dinner in your lap or take the food back to your campsite. PARKING - With 36 acres available to Stellafane Conventioneers, there is no lack of ground space for vehicles. The Springfield Telescope Makers ask you to just park in the designated areas and curtail your car lights during nighttime observing. However, as Conven-tion winds up to a Saturday night crescendo, proper parking spots become scarce. Insider Information: if you drive anywhere on Saturday, be back at Conven-tion by 3PM, park your vehicle and don't move it 'til Sunday morning! Be warned -an endless stream of local people coming just for the Saturday night festivi-ties seem to park all over the roadways, in the trees and atop unguarded tents… It really gets crowded! (continued page 9: More Stellafane) Eclipses Of The Sun Mayan Method By Dr. Lew Thomas and Anita S. Glick INTRODUCTION A solar eclipse must occur somewhere on the Earth each time the Sun arrives at a lunar node. This is because the Sun's motion is slow enough that the Moon surely will pass through a node while the Sun is close enough to be eclipsed. Therefore, a solar eclipse must occur at least every half eclipse year of 173.31 days on the average which is the time it takes the Sun to go from one lunar node to the other. Of course, a solar eclipse demands a new Moon which occurs each synodic month of 29.5306 days. THE MAYAN APPROACH We may ask how many days should elapse between each successive solar eclipse. At first you may think that 173 days would be a good approximation since it is close to half an eclipse year (173.31 days). However, we note that this figure divided by a synodic month yields the non-integer value of 5.85. Using 174 would yield 5.87. An eclipse table based upon these figures would quickly creep away from the time of new Moon. What approximation might we then use? The Mayan civilization of Mesoamerica had the answer even though their calindric system contained only whole numbers. Examining whole numbers in the vicinity of 173.31, we see that 177 and 178 result in the least departure from an integer when divided by the synodic month (29.530589 days). This is shown in Table 1. It is also possible for the Moon to eclipse the Sun just one synodic month short of an eclipse year. This occurs when, in the first instance, the Sun is west of a node, but eclipsable, and then half an eclipse year minus one synodic month later, the Sun is within 0.5 degree of the minor limit and is again eclipsable. Subtracting one synodic month from 173.31 yields 143.779 days. Table 2 shows that the best integer value to represent this span is 148 days. (Continued page 9: Eclipses) More Stellafane (continued from page 7) ABSOLUTE ASTRONOMY - Astronomical events run continuously from late morning to very early morn-ing. There are concurrent telescope making demos with hands on workshops, basic talks for beginners, daytime talks, evening lectures and optical judging for all 'scopes in competition. There is a constant bustle of amateur astronomers exchanging photos, trading fresh ideas and showing innovative equipment, honed since last year's Convention. If the skies are clear, solar ob-serving and eventually deep sky viewing continues non stop, with fellow observers more than happy to share views and enthusiasm. Insider Information: if you value your life and equipment, make sure all personal illumination has red lights, red filters or red LEDs. Even the lights of your vehicle should be disabled or wrapped with red tape or a light blocking cover. Look into www.smartastronomy.com to see night vision red filters specially made for laptop screens. POST CONVENTION EXODUS - It's always a sad time when you break camp and make the long trip back to the Mediocre World. On your way out of Springfield, you should visit the Porter / Hartness Telescope Mak-ing Museum in the Hartness House. Bear in mind the Museum's entrance, disguised as the Men's Room door, guides you to the telescope display via the cata-combs. That's an expedition all by itself! Insider Infor-mation: at Sunday morning breakfast, write down all the exciting things you experienced at the 2007 Con-vention, and list those points you would have done dif-ferently. Prepare now for next year's event, because Stellafane's inspiration stays with you forever. Eclipses (Continued from page 8) It is remarkable, that the ancient Mayans of Meso-america chose these very numbers -- 177, 178, and 148 -- with which to construct their solar eclipse tables. When an eclipse occurred, they would predict another eclipse 177, 178, or 148 days later . These are the very best choices possible and, more surprisingly, this was accomplished before the Greek and Roman empires flourished! Generally, 177 or 178 days occur between succes-sive solar eclipses and, for this interval to be valid, a lunar eclipse must occur between successive solar eclipses. When the generally intervening lunar eclipse is not present the interval between successive solar eclipses is reduced to 148 days. In the Dresden Codex of the Mayans, this 148 day interval is marked by plac-ing a picture immediately after its notation. If two solar eclipses occur without an intervening lu-nar eclipse followed by a lunar eclipse and then fol-lowed by two more solar eclipses with no intervening lunar eclipse, the occurrence sequence is: S S L S S where S represents a solar eclipse and L represents a lunar eclipse. The number of intervening days between the solar eclipses (ignoring the timing of the lunar eclipse) is: 147, 29, 149 or 148, 29, 147 or 148, 30, 147 days. These sequences are rare, and they apparently were not known to the Mayans. Adapted from Celestial Mechanics and Astro-nomical Mathematics for Amateur Astronomers,, 2nd Ed, Lewis Thomas, Copyright 1998 Skybox (Continued from page 4) be tidally locked, keeping one side pointed at the star at all times or possibly, if the gravitational attractions of the other planets in the system have a combined effect on it, the planet might have some sort of slow rotation period. The atmosphere would most likely exert some sort of greenhouse effect raising temperatures above the base figures given by the ESO astronomers. The slow rotation might make things even hotter. In short, Gliese 581b is most likely very different from the Earth, and it probably represents a class of planet never seen before, which would make interesting science by itself. One of the media pundits who bought into the "Earth's twin" hullabaloo was Judith Leblein, WCTC-AM's afternoon drive personality. She spent a good part of the afternoon the day when the discovery was announced taking calls about whether or not people would like to go to this "New Earth". I decided that I had enough of this, so I decided to send Judith an email with information about the planet, how little was known for certain, and why it was most likely not a twin of Earth. I included a plug for Astronomy Day at AAI. To my surprise, she replied and wanted me to call up to discuss the planet and AAI. The interview went fairly well, though it was a bit difficult to explain many of the concepts in the time allotted, as well as plug AAI. But, I think I cured her of thinking of Gliese 581b as an Earth-like planet. Unfortunately, the AAI angle did not go as well. While I was able to plug Astronomy Day, and even sent Judith a follow-up email inviting her to the event, she apparently had no interest. She did say, however, that she would keep AAI in mind if any space news popped up in the future. A Theory Why do the mainstream media seem to go gaga over even the slightest possibility of a habitable planet? I have a theory that might explain this as well as the fact that they also get a bit excited every time someone claims that something can go faster than the speed of light. One of the most popular science-fiction programs in the history of the world is the "Star Trek" franchise, which has many fans. While I like "Star Trek", I (as well as most fans) can tell that it is just entertaining fiction. Some, however, feel, at a subconscious level, that the franchise is a map to the future and they eagerly look for any sign that we are headed in that direction, hence the interest in habitable alien worlds and things that go faster than light. And some of those fans are probably in the media. As for me (and probably most of AAI), the actual search for extrasolar planets is interesting in its own right. 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 Membership 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: " Rotation of the Milky Way " Ways to enhance your tele-scope viewing " Details of Lunar Eclipses (Choice of topic at Dr. Lew's seminars is determined by participants' interest) FRIDAYS AT SPERRY June 22, 2007 Thomas Young: Light & Inter-ference Al Zuckerman June 29, 2007 Spielberg, Lucas and Kepler: Movie Music and the Math of the Universe Kathleen Quinn Vac-cari July 6, 2007 Optics 3: Linear and Circular Polarization, Filters, H-Alpha Filter Dr. Lew Thomas July 13, 2007 The Devil's Astronomy Steve Clark July 20, 2007 Apollo! The Anniversary of Apollo 11 Al Witzgall DOME DUTY SCHEDULE June 29 Team A July 6 Team B July 13 Team C July 20 Team D July 27 Team E 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 exec@asterism.org Executive Committee plus Trustees All schedules above were accurate at time of publication. Please check www.asterism.org for latest informa-tion (click on "Club Activities") Stunning Science from Our Solar System by Ken Kremer DAWN Asteroid Orbiter Nears Liftoff T his highly ambitious NASA mission is scheduled to blast off from Cape Canaveral this summer, when the launch window opens on July 7. The spacecraft will be mankind's first to orbit 2 bodies; Ceres the "dwarf planet" and Vesta, which are the 2 most massive objects in the Asteroid Belt. Ceres has a water ice rich mantle and a tenuous atmosphere whereas Vesta is rocky, oddly shaped and lacks a South Pole! Dr. Marc Rayman, Chief Engineer on DAWN from NASA's Jet Propulsion Laboratory in Pasadena, California described how this mission scenario is only made possible using exotic ion propulsion technology at a lecture in Princeton in March 2006 hosted by this author. Marc said that "these mini-plamets are inclined at 11 and 7 degrees to the ecliptic, respectively, and underwent different evolutionary paths". He emphasized that the mission is far beyond the capability of conventional chemical rockets. After launch, "a Mars gravity assist flyby is planned in 2009 at a distance of 500 km from the surface where the visible and infrared cameras and other science instruments will be utilized for science investigations", he said. DAWN spans 20 meters across, mostly due to the large solar panels. He told me that "the ion engine is a power hog that will require 550 watts to operate at the 3 AU asteroid encounter distance," nearly ˝ of the total electrical output of the solar array. Marc added that "after launch and at 1 AU the output is 10 KW, but drops to 1.2 KW at 3 AU." The energy is used to power the ion engine which then ionizes the Xenon gas propellant. The thruster "emits Xe+ and is adjustable at 112 discrete throttle levels, unlike most propulsion systems. The ion trail will be visible for about 1 meter or so." Phoenix Mars Lander to Launch in August NASA's second planetary mission this summer is set to launch on August 3. The spacecraft has been de-livered to the Kennedy Space Center for final payload processing. Phoenix will use retro rockets to land near the north pole of Mars in May 2008 where abundant sheets of water ice are located. She will dig several feet into the soil to retrieve samples for chemical analysis and determine the potential for biologic activity. Water is believed to be within inches of the Martian surface at the landing site newly located using imagery from NASA's powerful new Mars Reconnaissance Orbiter (MRO). The robotic arm is equipped with a scoop built by Honeybee Robotics. Honeybee also built the amazing and still functioning Rock Abrasion Tool, nick-named the RAT, for the Mars Exploration Rovers Spirit and Opportunity. Both Phoenix and DAWN will be launched on Delta 2 rockets. Artists Concept of Phoenix with Robot Arm and Scoop on Mars. Photo Credit: NASA/JPL/Corby Waste http://phoenix.lpl.arizona.edu/images/gallery/sm_139.jpg Uncover more Stunning Beauties from the Solar System in this month's Pictorial Supplement ! Please contact me for further information or public outreach presentations. My "Mars in 3-D" review article publishes on the cover of the Explorers Club Journal in June 2007. Upcoming Presentations include AAI, scheduled for 19 October 2007 Dr. Ken Kremer NASA JPL Solar System Ambassador Email: kremerken@yahoo.com Theater In The Sky by Ron Ruemmler July 2007 features the magnificent exit of Venus from the evening sky. Before the brilliant planet passes between the Earth and the Sun next month, we are favored with a lovely ballet between Venus, Saturn, Regulus and, briefly, the Moon. On the first evening of the month, Venus is less than one degree to the lower left of much dimmer Saturn and about eight degrees to the lower right of Regulus, the heart of Leo, the Lion. For the next two weeks, Venus moves to the left, toward the star. After that, Venus is at the left end of a horizontal line with Saturn on the right end and Regulus in between. All this time, Saturn is also moving toward Regulus, but much more slowly, so the whole complex is get-ting tighter. When the Moon flies past on the 16th all four objects are within 7.5 degrees. The entire formation gets lower every evening until just before the end of July, when everybody disap- pears into the glare of the setting Sun. Venus will not reappear as a morning object until late August. This is an unusually long period of invisibility due to a steep dive to the south as the planet passes between the Earth and the Sun. Before that happens, two thin crescents command our attention. The first is the crescent Moon, which passes through this gathering from the 15th to the 17th. The other is the crescent Venus, which is always a spectacular telescopic event whenever the planet is near inferior conjunction with the Sun. After twilight ends, Jupiter rules the southern sky. The brightest Summer constellation, Scorpius, the Scor-pion, stretches from just to the right of Jupiter, all the way down to the horizon. Jupiter is now setting before the start of morning twilight, but by that time a rapidly-brightening Mars is already up in the eastern sky. The Red Planet is all alone in empty Aries, the Ram. The best time to find Mars is in the wee hours of the 9th when it hangs below the waning crescent Moon. Mercury has a fairly favorable morning appearance during the last week of the month. The Earth always reaches its maximum distance from the Sun sometime during the first week of July. This year, however, this event seems to occur as late as it possibly can. July SKY CALENDAR 1 Sun 9:30 PM Venus 0.8 degrees lower left of Sat-urn and 8 degrees lower right of Regulus 6 Fri 8:00 PM Earth at aphelion, farthest from the Sun (94,508,722 mi) 7 Sat 12:54 PM Last Quarter Moon 9 Mon 3:30 AM Mars lower right of crescent Moon 12 Thu 9:30 Venus at greatest brightness (magnitude -4.5) 13 Fri 9:45 PM Regulus upper right of Venus 14 Sat 8:04 AM New Moon 16 Mon 9:30 PM Moon just left of Saturn and right of Venus and Regulus 20 Fri 11:00 AM Mercury at maximum elongation from the Sun 22 Sun 2:28 AM First Quarter Moon 29 Sun 8:49 PM Full Moon Stunning Science of Our Solar System by Ken Kremer Pictorial Supplement In this golden age of space exploration, two new planetary missions are set to launch while others continue to dazzle our imagination. Here for your enjoyment is this month's small sampling of beauties with previously undiscovered science that caught my attention as a NASA Solar System Ambassador. Neon Saturn Cassini flew over the unlit side of Saturn's rings to capture Saturn's glow, represented in brilliant shades of electric blue, sapphire and mint green, while the planet's shadow casts a wide net on the rings. This striking false-color mosaic was created from 25 images taken by Cassini's visual and infrared mapping spectrometer over a period of 13 hours, and captures Saturn in nighttime (right) and daytime (left) conditions. This image was acquired on February 24, 2007, while the spacecraft was one million miles from the planet and 34.6 de-grees above the ring plane. In this view, Cassini was looking down on the northern, unlit side of the rings, which are rendered visible by sunlight filtering through from the sunlit, southern face. On the night side at right, Saturn's own thermal radiation lights things up. This light at 5.1 microns wave-length (shown in red and some seven times the longest wavelength visible to the human eye) is generated deep within Saturn, and works its way upward, eventually escaping into space. An amazing array of dark streaks, spots, and globe-encircling bands is visible. This thermal emission dominates Saturn's dark side as well as the north polar region (where the hexagon is again visible) and the shadow cast by the A and B rings. At 2.3 microns (shown in blue), the icy ring particles are highly reflecting. At 3.0 microns (shown in green), the planet's sunlit hemisphere is bright. Thus the rings appear blue in this representation, while the sunlit side of Saturn is greenish-yellow in color. Within the rings, the most opaque parts appear dark, while the more translu-cent regions are brighter. In particular, the opaque, normally-bright B ring appears here as a broad, dark band separating the brighter A (outer) and C (inner) rings. Photo Credit: NASA/JPL /University of Arizona LPL http://photojournal.jpl.nasa.gov/jpegMod/PIA09212_modest.jpg Stunning Beauties of Our Solar System by Ken Kremer Pictorial Supplement Tvashtar Volcano Erupts on Io New Horizons: The Pluto bound planetary spacecraft rocketed past Jupiter on February 28 and has been slowly transmitting the results of over 700 scientific observations back to Earth. As Jupiter's moon, Io, rotates, the New Horizons spacecraft captured the giant 200 mile high erupting plume from the Tvashtar volcano in this composite of the best photos taken by the Long Range Reconnaissance Imager (LORRI) during its Jupiter flyby in late February-early March 2007. New Horizons was fortunate to witness this unusually large plume dur-ing its brief Jupiter flyby; the Galileo Jupiter orbiter spent more than five years imaging the volcanic moon (be-tween 1996 and 2001) without ever capturing such detailed pictures of a large Io plume. The cause of the fine wispy structure in the plume, which varies strikingly from image to image, is unknown, but these pictures may help scientists to understand the phenomenon. The pictures were taken at distances ranging from 1.9 to 1.4 million miles. In the final image, Io's shadow cuts across the plume and hides all but its topmost regions, and the glow of hot lava can be seen on the night side at the source of the plume. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute http://pluto.jhuapl.edu/gallery/missionPhotos/pages/050107/050107_03.html More Stunners to be unveiled in full color as part of next months "Beauties" and at my AAI talk on October 19, 2007. Please contact me for further information or public outreach presentations. Dr. Ken Kremer NASA JPL Solar System Ambassador Email: kremerken@yahoo.com