Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.aaa.org/EyepieceFiles/aaa/2008_09_September_Eyepiece.pdf Дата изменения: Sun Feb 22 20:31:02 2015 Дата индексирования: Sun Apr 10 03:48:22 2016 Кодировка: Поисковые слова: eclipse

Journal of the Amateur Astronomers Association of New York September 2008 Volume 56 Number 9, ISSN 0146-7662

EYEPIECE
to communicate. Tyson said he happens to like round things and see objects that can be listed with all their individuality. "That's why God added subcategories," Sykes added.
Tyson blamed American bate. "You go to Europe, Pluto." Tyson gave Pluto's Disney's dog and the word pl

The Never-Ending Debate Goes On: What Is a Planet?
By Thomas Haeberle
With all the hype of boxing match a n d m u sic b la r ing, the debaters walked in. Neil deGrasse Tyson, director of the Hayden Planetarium, strutted his stuff Mohammed Ali style. He supports the demotion of Pluto as a planet. In the other corner, Mark Sykes, director of the Planetary Science Institute in Tucson, disagrees with the 2006 ruling by the International Astronomical Union.
Their debate occurred during an August 14-16 conference, "The Great Planet Debate: Science as Process," at the Johns Hopkins University's Applied Physics Laboratory outside Baltimore. Moderator Ira Flatow of National Public Radio started off with "What defines a planet?" Tyson took the first swing, saying the word "has no scientific value, the word has no utility. It's time to take pause and come up with a new lexicon. It had utility with the Greeks and other [ancient] cultures." Tyson would like to invent an entirely new system. Sykes replied, "We need to categorize things as a science process. Give us a tool to see how these work." Flatow interrupted, "So the IAU definition is not useful," to which Sykes seemingly agreed. Tyson interrupted, "You wanted a definition, they gave you a definition and now you're complaining," to the delight of the audience. "And I'd like to add..." with Sykes cutting him off: "I've got to start for you to add." Sykes and other scientists a r e in t er est ed in t h e physical characteristics of objects such as planets. Tyson and those of his thinking feel where an object has orbital dominance, the ability to clear its orbit makes it a planet. Tyson conceded that the IAU definition "falls short of information," but is useful in that it gives scientists a way

culture for t h e p la n et d eand they don't care about background and lineage to utocracy.

He noted the IAU committee had no expert on exoplanets and no expert on Kuiper Belt Objects. Sykes said, "If you look at stars with exoplanets, if they were Earth mass and if round, [how do we know] they clear their orbit?" He pointed out that at the IAU meeting Pluto was a dividing wedge between two opposing camps when it shouldn't have been. Tyson feels we need definitions that agree with what we observe in our solar system and other star systems. Questioning the premise of wh a t 's a planet, Tyson went through the history about the mysterious gap in our solar system. When objects were being found in this zone in the 19th century, he said, "people then took pause to say maybe something else is going on there, and took the other newfound [minor] planets away." Planet Debate continued on page 10

Reminder: Urban Starfest Is September 6
The annual Urban Starfest takes place Saturday, September 6 in the Central Park Sheep Meadow from dusk to 10. See president's letter on page 3 for details.


What's Up
By Tony Hoffman The Sky for September 2008
Planets Dance in the Twilight. T h ou gh Sa t u r n is gone from the picture, lost in the solar glare, Mercury, Venus and Mars continue their dance in the evening twilight. Of the three worlds, only Venus, at magnitude -3.8, is easily visible without binoculars. The three remain in a close grouping, all within a 5-degree circle, for an amazing 17 days (September 3 to 19). Over that period, Mercury fades slightly, from magnitude 0 to 0.3. Mars is tough to see without optical aid at magnitude 1.7. On the evening of September 11, Venus and Mars pass less than 1/3 degree from each other. The next night, Mercury passes 3.4 degrees from Mars. A week later, Mercury and Mars have a second conjunction, lying 4 degrees apart. The first-magnitude star Spica is also near the three planets in the second half of the month. September's Constellations. T h e h ea r t of ou r ga la xy is well placed for observing early on September evenings, with Scorpius to the southwest and Sagittarius, which holds the dazzling world Jupiter, in the south. Ophiuchus, Aquila stand higher in the south, Vega is at the zenith and Cygnus high in the east. Hercules slips westward. Orange Arcturus twinkles in the west, setting a few hours after the Sun, and the Big Dipper swings down into the northwest. The Great Square of Pegasus lies to the east, trailed by Andromeda and Perseus, with Cassiopeia above. Capricornus, carrying the 8thmagnitude planet Neptune, rises in the southeast, followed by Aquarius, in which Uranus comes to opposition on September 12-13. Fomalhaut shines blue-white, low in the south. Heralding the arrival of the winter stars, Capella and the Pleiades rise before midnight. September 1 M oon lies n ea r M er cu r y a n d Ven u s. September 2 M oon lies n ea r M a r s. September 6 M oon lies n ea r An t a r es. September 7 F ir st -quarter Moon at 10:04 a.m. Io and Ganymede cast simultaneous shadows on Jupiter between 8:12 and 8:38 p.m. September 9 M oon lies n ea r J u p it er . September 11 M er cu r y lies 4 d egr ees fr om Ven u s; Venus passes 0.3 degrees from Mars. September 12 M er cu r y lies n ea r M a r s; Ur a n u s a t
2

On September 18 and 19, Mercury, Venus, Mars and Spica all fit within a 5-degree circle.

opposition. September 15 F u ll M oon a t 5: 13 a .m . September 18 Ven u s lies 3 d egr ees fr om Sp ica . September 19 M er cu r y p a sses 4 d egr ees fr om M a r s; Moon at perigee, 229,215 miles from Earth, 11:27 p.m. September 22 L a st -quarter Moon at 1:04 a.m.; autumnal equinox at 11:44 p.m. September 23 M a r s lies 2 d egr ees fr om Sp ica . September 27 M oon lies n ea r Sa t u r n . September 29 New M oon a t 4: 12 a .m . September 30 M oon lies n ea r M a r s.

Jupiter Rules the Evening Skies
By Joseph A. Fedrick
Jupiter reached opposition J u ly 9 a n d r ose ea r ly enough so that by July 24, I could observe it by 9:15 p. m. with my 6-inch Newtonian scope at 150x. The Great Red Spot had just crossed the meridian and appeared as very pale salmon pink. The two prominent equatorial belts were gray-brown, the north belt having a slightly orange tint. The south belt was divided into two belts by a pale tan rift. I observed the spot lying in a hollow in the south equatorial belt on several later evenings in August. It appeared to cross the meridian center line. The Great Red Spot had apparently not drifted significantly from its predicted location. There were several wavy ripples on the southern edge of the south equatorial belt. One may have hid the tiny new red spot.

Fedrick continued on page 10


A Message from AAA President Richard Rosenberg
Hello, members: Our annual Urban Starfest in the Sheep Meadow of Central Park takes place Saturday, September 6, from dusk to 10. Several members will bring their telescopes and binoculars to how off the sky. If you're bringing a scope and coming by car, nearby free parking can be arranged. Give me you car 's license plate number, make, model and color. Invite your family and friends; the sky is for everyone. Early on we'll check out the Moon near the bright red star Antares. large moons--Io, Europa, Ganymede and Callisto--will be visible, though Also visible will be a variety of objects including the Ring Nebula, Andr beautiful double Star Albireo. If the weather is inclement, Sunday the 7th Later, Jupiter will be featured. All four of its Io will pass behind Jupiter shortly before 10. omeda Galaxy, Neptune and Uranus, and the is the rain date.

On Friday evening, September 26, the Parks Department will host a nature walk and solar observing from 6 to 7:15 p. m., followed by stargazing. We'll be in Wagner Park along the Hudson at the southern end of Battery Park City. David Kraft, chair of the AAA lecture series at the American Museum of Natural History, has put together another excellent lineup of speakers for 2008-09. The series begins on Friday, October 3 with Mordecai-Mark Mac Low of the AMNH speaking on "The Puzzles of Planet Formation." at 6:15 p. m. at the Kaufmann Theater. See the story below for the names of our other speakers. We're developing a relationship with the Brooklyn Bridge Park Conservancy. They've recently obtained from the Sci Fi Channel four 10" Dobsonian telescopes, and we will help to staff these scopes at public events. Check Events on the Horizon or our website in the future. Unfortunately, due to difficulty in getting our liability insurance modified, it looks like our observing sessions at North-South Lake in the Catskills will have to wait until next year, but I promise we 'll have regular out-of-town observing next year. Our Recent Advances Seminar continues to thrive at New York University. We have a regular location there at last: from 6 to 8 p. m. at Room 801, 239 Greene St. Give it a try Thursday, September 14. I think you'll like it. Rich Rosenberg, AAA President, pr esident @a a a .or g, (718) 522-5014

Planet Formation Talk Begins AAA Lecture Series October 3
Mordecai-Mark Mac Low, ch a ir of t h e a st r ophysics department at the American Museum of Natural History, will open the AAA's 2008-09 lecture series Friday, October 3 when he speaks on "The Mysteries of Planet Formation." The free public lecture begins at 6:15 p. m. at the Kaufmann Theater of the museum. Discussing his talk, Mac Low says: "How did the Earth and other planets form? We now understand the broad outlines of the process by which interstellar dust and gas come together to form planets. However, at several points in the chain of events, attempts to theoretically describe the next step suggest that everything should fall into the central star. As this contradicts everyday observation, the theory has had to be improved. I will describe problems with boulder drag and planetary migration, and describe theoretical suggestions that appear to explain why the Earth indeed exists." Mac Low holds a Ph.D. from the University of ColLectures continued on page 9
3


Home Depot Aids Capital Improvements at Custer Institute
The Custer Institute in Sou t h old , N. Y., h a s a n ew roof and gutters thanks to a donation by Home Depot. "The Institute has needed a new roof for quite some time," says president Donna L. McCormick. "We operate on a shoestring and have no endowment, so we were unable to fund the repair ourselves. This past spring, a windstorm blew off a batch of shingles and within days a dinner-plate-sized hole appeared that went through the roof to the ceiling of the lecture hall below." Visitors joked that the hole gave stargazers another place through which they could look at the sky, but it wasn't funny when rain poured in during classes. `Two local contractors patched the outer hole without charge, but there was no question that our time had run out and a new roof was needed asap." In desperation, M cC or m ick wr ot e H om e Dep ot ceo Frank Blake and asked for help. Within a few weeks, she received a call from the corporate office in Atlanta. "I absolutely couldn't believe it. Home Depot was willing to come to our rescue." Home Depot sent a large-enough crew of workers to accomplish the work in one day. They arrived the morning of August 5, removed the old roof, replaced whatever damaged wood they found in the underlayer, put on a new layer of shingles and installed the gutters." The institute next hopes t o fin d h elp t o r ep a ir t h e damage the leaky roof caused in the lecture hall, meeting room and library. Ceilings need patching, rooms need painting and there's need for electrical work. Once that's done, it plans on tackling the basement, where it can no longer hold workshops because of unhealthy conditions from mold due to dampness from water penetration, cracked windows and bad grading.

New Dome Awaited at Greenwich (CT) Observatory
Members of the Astronomical Society of G r een wich, Conn., (ASG) are eagerly awaiting a new dome on the Bowman Observatory. "Work was supposed to start in February, so we cleaned the place out then," notes Anne Burns, an official with the Bruce Museum, with which the ASG is affiliated. "Then they didn't start until May. We've continued to hold our public nights on the lawn, with smaller scopes." Burns fills Ey epiece in on the background and recent developments: "The Bowman observatory b elon gs t o t h e G r een wich Board of Education. It was built in the 1940s by Alden W. Smith, a science teacher at Greenwich High School, and is on the grounds of Julian Curtiss Elementary School in downtown Greenwich. "The ASG was formed in 1984 and one of its goals was to reopen the observatory, which had fallen into disrepair after Smith's death. Dr. Frank Lawlor, who was then science curator of the Bruce Museum, invited the club to meet there. The ASG still has our meetings there, and our events are listed in the museum newsletter, but
4

we run the observatory separately.

"With the help of several members of t h e R ep r esentative Town Meeting (RTM), we persuaded the town to allot some funds to renovate the observatory. We also got several private donations and a federal matching grant. Though we didn't meet our goal of reopening for Halley's Comet, we were able to reopen in the fall of 1986. The Board of Education allows us to use the observatory on condition that we open it to the public, which we do twice a month. Rick Bria, a founding member of the club, is in charge of public nights.
"The old dome, which was original to the building, was refurbished in 1986 but started rusting and leaking again several years ago. Bill Bambrick, one of our members, who is also an RTM member, led the charge to get funding to replace it. He also did most of the legwork researching possible new domes, and energetically pushed the project through to its present state of nearcompletion. "So far I haven't heard a n yt h in g a b ou t wh en t h e observatory may be back on line. Until it is, we are holding our public nights on the lawn in front of the building, using smaller scopes."


Time Magazine Readers' Questions for Tyson
Time ma ga zine's "10 Questions for..." feature, which culls questions from readers, recently spotlighted Hayden director Neil deGrasse Tyson. The Q&A: What is the difference between astronomy and astrophysics? There was a day long ago when all you could do to study the universe was pull out a telescope and look up. Physics did not come of age until the late 1800s. Now any modern-day astronomer is also an astrophysicist. We use them interchangeably. What should be done about the fact that American children lag behind kids in other countries in science and math? We need to do something about the stigma. Somehow it's O.K. for people to chuckle about not being good at math. Yet if I said I never learned to read, they'd say I was an illiterate dolt. You can't look at science and math as separate. They're fundamental to what it is to be alive because they're all around us. Which area of astrophysics interests you the most? I'm fascinated by the deaths wreak on their environments. the subjects the public likes: missions, black holes, the Big of stars and the havoc they As a public scientist, I like the search for life, NASA Bang. world. Does this keep you up at night? Yes! If it doesn't keep you awake at night, what's wrong with you? However, it might keep me awake in a different way. I think of ways to prevent them. How long will it be until we colonize other planets? Do you know that Antarctica is balmier and wetter than the surface of Mars? Yet I don't see people lining up to build condos in Antarctica. So how long? A thousand years. Never. We can visit them. But to land there and say, "What an oasis!"--not anytime soon. If you could meet any scientist who ever lived, who would it be? Isaac Newton. No question about it. The smartest person ever to walk the face of this earth. The man was connected to the universe in spooky ways. He discovered the laws of motion, the laws of gravity, the laws of optics. Then he turned 26.

What is your favorite science-fiction movie, and in that movie, what science is plausible?
"Deep Impact" and "Comet getting the science right. I'm directors to get their science than they believe, the science anything they can invent. ." They spent a lot of time on a crusade to get movie right because, more often is more extraordinary than

Do you believe in possible extraterrestrial life? Anyone who has studied the problem recognizes the likelihood that there's life elsewhere in the universe. Now, if you want to say that there is life out there that is intelligent and built a flying saucer and traversed the galaxy to come here and land on Earth and be spotted by people who see lights in the sky ... okaaay. What is your favorite part of the work you do? When someone comes up to me with a question about the universe. And I reply. And I see the person's eyes light up because they learned something new. You talk about events that can cause the end of the Do you think that man is fully capable of understanding the universe's design? I lose sleep at night wondering whether we are intelligent enough to figure out the universe. I don't know.

Contacting the AAA
If you want to join, volu n t eer , p a r t icip a t e in even t s, have a question or change your address, e-mail members @aaa.org, or leave a message at AAA hq: (212) 5352922. Also, visit us on the web at www.aaa.org. If you want to write an article for Ey epiece, contact editor Dan Harrison at editor@aaa.org or (914) 762-0358.
5


Review: Titan Provides a Cornucopia of Information
By Terrell Kent Holmes
Owing to its size a n d u n iq u e p r op er t ies, T it a n , Saturn's largest moon and the second largest in the solar system, after Jupiter's Ganymede, has almost as much planetary status as any terrestrial planet, and certainly more than the recently redesignated Pluto. Ralph Lorenz and Jacqueline Mitton have written "Titan Unveiled" (Princeton University Press, $29.95), a hybrid of scientific history, memoir and a follow-up to the authors' "Lifting Titan's Veil." This is almost two books in one: the dry, technically detailed text balanced by Lorenz's lighter, more personal log entries with insights just as interesting. The Cassini-Huygens project was multinational, with NASA working with the European Space Agency to fund and build it. The ESA worked on Huygens while NASA was primarily responsible for Cassini's payload. In 1997, the Huygens probe, which was piggybacked onto the Cassini spacecraft and dropped onto Titan's surface, provided a wealth of information. With NASA and the ESA working together, another orbiter was planned, but with NASA building the orbiter and ESA building and funding the probe. Titan's atmosphere, a b ou t wh ich a st r on om er s h a d known since 1944, was a lure. Voyager was able to only provide information about the atmosphere but not the surface due to inadequate instrumentation. The bulk of Titan's atmosphere, like Earth's, is nitrogen. Titan's atmosphere, however, is four times denser at the surface. Titan also has an axial tilt close to Earth's 23.5°, resulting in seasons (although much longer, owing to Saturn's 29.5-year solar orbit). At the time of the mid-90s, around the time Cassini was preparing for its fly-by, observational and theoretical advances were being made that would enhance the exploration of Titan. Lorenz wrote a brief log entry in December 2003 that showed how astronomy had changed, and how mundane it can be. He mentioned, while at the Kuiper 61-inch telescope in Arizona, that a lot of observing is actually done on the Internet. Moreover, accidents happen. Lorenz, a Johns Hopkins planetary scientist, destroyed a $10,000 CCD camera during an observing session, and an attempt to
6

observe Titan at a critical juncture was almost thwarted by a missing piece of small but vital equipment. He had to break into a storage room to get it. The advent of adaptive optics made Titan even more popular to observe. And amateur astronomers made their contribution, such as the discovery of clouds on Titan. It was believed for years t h a t T it a n wa s t h e la r gest satellite in the solar system. With data supplied by Voyager I, however, it was determined that Titan is 37 miles in diameter less than Ganymede. Titan's distinctive feature, its considerable atmosphere, made an accurate measurement of its diameter difficult because it made Titan's disc look larger than the solid body really is. Cassini-Huygens launched on October 15, 1997 and took seven years to reach Saturn. After the initial adrenaline rush of landing on Titan, it was time to sift through the data for valuable nuggets, interpreting puzzling or contradictory data. The one aspect of Titan that makes it so attractive is atmospheric and topographical resemblances to Earth. The Earth analogues with Titan were correct, or close. There are mapped regions of the satellite named "Xanadu" and "Shangri-La." A planet or satellite with an atmosphere has noticeable weather patterns. The meteorological processes on Titan, and its overall nature, can tell scientists a lot about the evolution of the Earth, which is why this distant world is under such scrutiny. While the composition of Earth's and Titan's atmospheres differ greatly, their geological evolutions may have been similar. Indeed, the interpretation of the initial images of Titan taken by Cassini seemed to capture views resembling coastlines and islands. Eleven years and 1 billion miles later, t h e C a ssin i/ Huygens mission is still just beginning. Despite all the data, analogues and theories, there are still aspects of Titan astronomers don't understand. By the time Cassini was ready for liftoff, Lorenz and his colleagues knew they were working in the face of impending obsolescence, soon to be engendered by a torrent of gigabytes of new data from Cassini/Huygens. As more new information comes in about this fascinating object, one thing appears certain: "Titan Unveiled" will have to be rewritten.


Briefs: Phoenix Mars Lander Confirms Existence of Water
NASA's Phoenix Mars Lander con fir m ed t h e exist ence of water ice on Mars. Scientists saw evidence for water ice before in observations by the Mars Odyssey orbiter and in disappearing chunks observed by Phoenix, but this is the first time Martian water has been so analyzed. Meanwhile, new results from the lander suggest surface layers of the Martian arctic may not be as friendly to life as initial results suggested. They suggest Martian dirt may contain perchlorate, a highly oxidizing substance, which would create a harsh environment for life. The findings stand against results from a first analysis, which indicated the dirt was Earth-like in certain respects. Phoenix's mission has been extended for a month. A tiny Canadian satellite is gea r in g u p for a m ission to hunt wayward space rocks that may threaten Earth. Only the size of a suitcase, the Near Earth Object Surveillance Satellite has a 5.9-inch telescope and weighs 143 pounds. It's designed to hunt for threatening space rocks from Earth orbit, where it can avoid interference from our atmosphere. Launch is set for 2010. New findings indicate m a gn et ic exp losion s a b ou t one-third of the way to the Moon cause the northern lights to burst in spectacular shapes and colors, and dance across the sky. The findings should help scientists better understand the more powerful but less common geomagnetic storms that can knock out satellites, harm astronauts in orbit, and disrupt power and communications on Earth. A supernova spotted ea r lier t h is yea r m a y r ep r esen t a cosmic event closer to gamma-ray bursts than stellar explosions. Researchers suggest that supernova SN 2008D resulted from a massive star collapsing into a black hole. That event produced a five-minute long burst of X-rays, which Swift detected January 9. A giant, glassy lake la r ger t h a n L a k e O n t a r io gr a ces the south pole of Titan, Saturn's largest moon, new research confirms. This is the first observation that pins down that Titan has a surface lake filled with liquid. Called Ontario Lacus, the lake extends 150 miles and covers an area of 7,800 square miles. The lake structure is filled mostly with liquid methane and ethane. Scientists have discovered a J u p it er -sized planet orbiting a distant Sun-like star. The planet takes 9.2 days to transit its star, the longest period for any transiting exoplanet found. By tracking the time between transits, scientists measured how long the planet takes to revolve around its star, and found it's the same period of time its star, slightly larger than our Sun, takes to rotate 360 degrees. This is the first transiting exoplanet found with a peculiar combination of mass and period of rotation. Meteorites that fall to Earth u su a lly com e d ir ect ly from the asteroid belt between Mars and Jupiter, rather than from the population of larger space rocks that drifted in from the asteroid belt's innermost edge to hang around our planet's neighborhood. The finding explains why the makeup of most meteorites doesn't match the composition of most near-Earth asteroids. A new study indicates ou r sola r syst em m a y b e r a re. A group of astronomers surveyed Sun-like stars in the Orion Nebula open cluster and found that fewer than 10% have enough surrounding dust to make Jupiter-sized planets. Since most stars in the galaxy are believed to form in dense, Orion-like regions, this implies systems like ours may be the exception. That's important because giant planets like Jupiter may be instrumental in fostering life on rocky worlds like Earth. Jupiter's Great Red Spot h a s r ou gh ed u p a you n ger rival storm and may consume it. The baby red spot appears to have gotten the worst of its encounter with the super-storm that has dominated Jupiter for at least two centuries. Another super-storm, the Little Red Spot, safely skirted its larger cousin and may challenge the Great Red Spot for size. The Little Red Spot's top winds already equal those of the Great Red Spot at 384 mph. NASA unveiled a beefed-up r ed esign of a p r op osed Moon rocket. The Ares V spacecraft that's to carry astronauts in 12 years will be 38 stories tall and carry a heftier load than earlier planned. The rocket will be 20 feet longer than a previous design and have six main engines at its base, not five. Engineers will enlarge the twin solid -rocket boosters so it can hold more fuel and carry more supplies and equipment. Ares V will carry 15,600 pounds more than the original concept. The rocket will carry four astronauts and a lander. Ares V will be able to send more than 156,600 pounds of cargo. Major work on 7 Continued on page 8


Briefs: Peony Nebula Star Is 2nd Brightest in Milky Way
Continued from page 7 Ares V begins in 2010. A known star has re-emerged a s t h e secon d b r igh t est in our galaxy. The Peony Nebula star shines as brightly as 3.2 million Suns, but had lurked in obscurity among interstellar gas and dust in the central region of the Milky Way. Spitzer scoped out the star behind the Peony Nebula's reddish cloud of dust. Other stars are much brighter as seen from Earth, but that's because of their proximity. Distance and dust sheltered the Peony Nebula star from observers 26,000 light-years away. The brightest star, Eta Carina, has the light of 4.7 million Suns. Galaxies much like ours h a r b or m yst er iou s m a gn et ic fields, which turn out to build up much faster than scientists realized, a new study has found. By analyzing light coming from distant galaxies at a time early in the universe's history, astronomers were able to show these galaxies developed magnetic fields much sooner than expected. Astronomers observed very distant quasars in visual and radio-frequency light. Radio waves often showed signs of passing through a magnetic field. It turned out, when a normal galaxy lay between Earth and the quasar, the magnetic field signature on the light was most strong. This showed it was the foreground galaxies, not the quasars, that held the responsible magnetic fields. NASA's Deep Impact spacecraft h a s m a d e a m ovie of the Moon passing in front of the Earth from the probe's vantage point millions of miles away. Astronomers will use the video to develop techniques to look for Earth-like worlds in other solar systems. Making a video of Earth from so far away helps the search for other lifebearing planets by giving insights into how a distant, Earth-like alien world would appear to us. Deep Impact is the first craft to show a transit of Earth with enough detail to see large craters on the Moon, and oceans and continents on Earth. The video shows specific features important for observations of Earth-like planets. Our galaxy's dark matter is clu m p ier t h a n on ce thought, according to a new computer simulation. The model, created by one of the most powerful supercomputers in the world, shows that the spherical halo of dark
8

matter that envelopes the Milky Way contains dense clumps and streams of the mysterious stuff, even in the neighborhood of our solar system. Spiral galaxies with bar-shaped a r m s m a y n ot h a ve been born that way. Astronomers found the number of bars has tripled in the past 7 billion years, indicating spiral galaxies evolve as they age. Barred galaxies are shaped like a tiger's eye, with two starry arms trailing off either end of a long, dark stardust lane. They take shape as stellar orbits in a disk become unstable and deviate from a circular path. After settling down, the only other dramatic way for galaxies to evolve is through the action of bars. More than two-thirds of spiral galaxies, including the Milky Way, have a bar-shaped path through their middles. Astronomers say the bar scene was very different 7 billion years ago. They discovered that while spiral galaxies were around in the distant past, only 20% of them possessed bars that are common in their modern counterparts. Bars form mostly in small, low-mass galaxies and grow in galaxies after stellar orbits in a spiral galaxy begin to deviate from a circular path.

Clay deposits in one of t h e old est r iver b ed -like channels on Mars show unusual signatures that may shed light on the history of water, and possibly life, there. Observations made by the Mars Reconnaissance Orbiter show substantial clay deposits that formed 4 billion years ago in two regions of Mars and indicate water was more widespread in those areas than initially thought. A new study took a closer look at clays in one region and found they lie in in a uniform sequence of layers that indicate the chemistry of water there changed over time.
A new map of the halo of st a r s t h a t su r r ou n d s t h e Milky Way has revealed a complicated structure of crisscrossing stellar streams, many of which never detected. The halo begins at the edge of the disk 65,000 light-years from the galactic center and may extend to 300,000 lightyears from the center. The halo has star clusters, clouds of gas, dark matter and a few lone stars. Some of these pieces were grabbed by the Milky Way from dwarf galaxies passing by. The halo's largest stellar streams have been mapped over the last decade, but new Sloan data have found many previously unknown smaller streams, remnants of dwarf galaxies that strayed too close and a few surviving companions. The streams are remnants of


Events on the Horizon September 2008
M: members; P: open to the public; T: bring your telescopes, binoculars, etc.; C: cancelled if cloudy; HQ: at AAA headquarters, 1010 Park Avenue (between 84th and 85th streets); AMNH: For ticket information, call (212) 769-5200 For directions to AAA observing events, check the club's website at www.aaa.org. Monday, September 15, 7:30 p. m. Hayden Planetarium lecture, P, AMNH Carolyn Porco, director of the Cassini Imaging Central Laboratory for Operations, will discuss the significance of the Cassini spacecraft and its Huygens Saturn probe. Saturday, September 20, dusk Observing at Great Kills Gateway National Park, Staten Island, P, T, C Next date: October 4 Friday, September 26, dusk-10 p. m. Observing at Carl Schurz Park, Manhattan, P, T, C Friday, September 26, 6-7:15 p.m. Sunset nature walk followed by stargazing, Robert F. Wagner Park, Battery Park City, Manhattan, P, T Saturday, September 27 10 a. m.-noon Solar Observing, P, C Conservatory Waters, Central Park. Next date: October 25 Saturday, September 27, 1-4 p. m. Observers' Group, M, HQ Next d a t e: O ct ob er 25 Guard and NASA, "STS-115: An Assembly Mission to the International Space Station"; December 5: Da vid Hogg, NYU, "Automated Calibration of Astronomical Imaging and the Open-Source Sky Survey"; January 2: Robert Nemiroff, Michigan Technological University, "Astronomy Picture of the Day"; February 20: J osep h Patterson, Columbia, "The Center for Backyard Astrophysics"; March 13: Neil d eG r a sse T yson , AM NH , "The Rise and Fall of Pluto--Witness to Demotion" (John Marshall Memorial lecture); April 3: Rick Fienberg, S k y & T elescope and Phillips Academy, "The More Things Change"; May 1: Den t on E b el, AM NH , "The Stardust and Genesis Sample Return Missions."
9

Tuesday, September 2, dusk-10 p. m. Observing at Cadman Plaza, Brooklyn, P, T, C Next date: October 21
Friday, September 5, 8-10 p. m. Observing at Floyd Bennett Field, Brooklyn, P, T C Next date: October 3 Saturday, September 6, dusk-10 p. m. Stargazing, Urban Starfest, P, T The AAA, in conjunction with the Urban Park Rangers, presents this annual event in the Central Park Sheep Meadow. Rain date: Sunday, September 7. Wednesday, September 10, 8-11 p. m. Observing at Prospect Park, Brooklyn, P, T, C Next date: October 8 Thursday, September 11, 6-8 p. m. Recent Advances in Astronomy Seminar, M Check aaa.org for NYU location. Next date: October 9

Lectures continued from page 3 orado in physics. He pursued his interests in computational simulation of interstellar gas, star formation, galaxy formation and, more recently, planet formation, during postdoc fellowships at NASA Ames, University of California/Berkeley and the University of Chicago before joining the Max Planck Institute for Astronomy in Heidelberg, Germany. In 1999, he was the first curator to join the AMNH's astrophysics department. Other upcoming AAA lectures are: November 21: Da n iel Bu r b a n k , U. S. C oa st


Planet Debate continued from page 1 He pointed out Pluto was grandfathered in as a planet even though like objects were being found in the outer region of our solar system at the end of the 19th century. "And I am certain Pluto is happier there," he insisted . "William Herschel, wh o h a d d iscover ed Ur a n u s, in fact coined the term 'asteroid' (star-like) to describe Ceres in something of a put-down," Sykes explained. In the following centuries we learned that Ceres contained about half the mass of the asteroid belt and thermal modeling indicates it may be warm enough to have a liquid ocean beneath its surface. "Pluto is very different from the asteroids," he noted. Sykes' and Tyson's original tussling over Pluto was discussed in a N ew Y ork T im es article in 2001, "Pluto Not a Planet, Only in New York," which let the genie out of the bottle. Tyson talked about the museum's decision to excommunicate Pluto and why it's wrong to count planets. For example, he'd like to see Titan and Earth in the same category. It seemed at times T yson a n d Syk es wer e h a lfh ea r t edly agreeing rather than firmly disagreeing, perhaps showing hope the two sides may come together on what may be considered a true definition of what is a planet or

maybe not. In closing the debate, Sykes said, "I get the feeling Neil is coming over to the right side of the fence." Tyson's response: "The delusion continues." Fedrick continued from page 2 A tiny kink in the south temperate belt appearing near the Great Red Spot may have been the location of Red Spot Junior. However, less than perfect seeing and limited resolution of my 6-inch scope prevented my seeing these spots clearly. Bruce Kamiat reported observing Jupiter on July 25 at the Observers Group meeting. However, by that time the red spot was not facing us so he reported seeing the very large disk of Jupiter and the equatorial belts. Jupiter should be an exciting target to observe during September, being in the south at dusk.

Babylon Board OKs Light Bill
The Babylon Town Board on L on g I sla n d h a s passed light-pollution legislation, the key requirement of which states that "all exterior lighting rated to be lamped at 1,800 lumens (100 watts incandescent) and greater shall use full-cutoff luminaires...and be installed as designed with the light source directed downward." All exterior lighting 1,800 lumens and less shall use fully shielded fixtures. All exterior lights shall be full-cutoff. . Nonconforming exterior lighting already installed is exempt but must meet requirements.

Amateur Astronomers Association 1010 Park Avenue New York, NY 10028

Forwarding and Address Correction Requested 10

First Class