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Journal of the Amateur Astronomers Association of New York August 2007 Volume 55 Number 8, ISSN 0146-7662

EYEPIECE
understand dark matter is to locate it, and observe its structure and function in the universe, and this is what Massey and his team set out to do.
The brilliance lies in how they did it.

How a CalTech Team Located and `Observed' Dark Matter
By Rachel Berger Connolly
CalTech astronomer Richard Massey knows how to appeal to a broader New York City audience: pizza. He began his June 12 lecture at the Hayden on dark matter, "Mapping the Invisible," with a comparison between images of galaxies and clusters, and different kinds of pizza. Suddenly, pizza became a laboratory for a discussion on how the CalTech team that Massey led used the Hubble COSMOS survey, among other sources of data, to map a 3D region of dark matter in the universe.
Pizza or no pizza, if you're insecure with the unknown, this was not the talk for you. Since "dark" means hidden from knowledge and mysterious, as well as the absence of light, it's a good name for this kind of matter that doesn't emit or reflect light. Even in the face of current technology, the properties of dark matter are little known. The other stuff, the "ordinary" matter, is what we're made of. Called baryonic material by scientists, these protons and neutrons make up atoms, cells, people, planets and everything that we observe and interact with. Despite its lack of social skills, dark matter is all around us--whizzing through us right now. The good news is it doesn't affect us. So how did we know that we were missing something in the first place? Astronomers took an audit, like cosmic accountants. From their observations of galaxies, astronomers realized that to balance the gravitational books, to keep galaxies spinning and swarming around each other at the speeds they do, much more mass is needed than what they observed. How much? Only 4% of the universe is ordinary matter; the rest is 23% dark matter and 73% dark energy, an even more mysterious component that wasn't in the scope of Massey's talk. The first step to

Historically, observations of light have helped us to understand gravity. Galileo's observations of the motions of Jupiter's largest moons became the seeds of Newton's Law of Gravitation. With gravity and light much better understood, they're partnering to allow us to shine light on the existence of dark matter. Once dark matter is better understood, it might shine some light on dark energy. If we can't see dark matter directly, we can probe its effects on the universe. The large-scale structure of dark matter can be mapped through gravitational lensing. Imagine that you're looking at a distant, bright galaxy. A tiny portion of light that leaves this galaxy travels through space in a straight line and is collected by your eye or telescope. Now imagine a clump of dark matter is between you and this galaxy. Light from the galaxy has to pass through the dark matter before it reaches you. The clump of dark matter doesn't interact with the light directly, but as a mass, it causes the space around it to pucker and warp. The straight lines the light is traveling along become skewed, distorting the image of the background galaxy. This distortion can be used to map the presence and amount of dark matter light from distant galaxies had to pass through. The next step in developing this dark-matter map was to look out into the universe at different depths to build the map's third dimension. This also yields a sense

Dark Matter continued on page 3


What's Up
By Tony Hoffman The Sky for August 2007
Good Prospects for Perseids. T h e P er seid m et eor shower is scheduled to peak on Monday morning, August 13. Moonlight won't interfere as the Moon is new that night. Normally, nearly one Perseid per minute can be seen from a dark-sky site, but some predictions suggest that up to twice that many may be seen around 4 a.m. The Perseids usually stay strong within a couple of days of peak, so it's likely that Sunday morning will also be promising for meteors. A Predawn Lunar Eclipse. T h e secon d t ot a l lu nar eclipse in less than six months will occur on the morning of Tuesday, August 28. Unlike March's eclipse, which was well placed for viewers in the evening sky, this eclipse won't be visible until around 4:30 a.m. for observers on the East Coast. The darker, umbral phases will start shortly before 5 a.m. The eclipse won't be total until twilight begins to brighten the sky, and the Sun will rise while the Moon is fully eclipsed. August's Planets. Vir go st a n d s a b ove t h e su n set early on August evenings. Comet 2006 VZ13 (LINEAR), unexpectedly bright at press time at mag. ~7.5, makes a trek through the Virgo cluster of galaxies this month. Jupiter shines north of Antares, with the asteroid Vesta scooting just half a degree below the largest planet and its moons on the night of August 29. Neptune reaches opposition near Iota Capricornii on August 12, at magnitude 7.8, a challenging object from the city in binoculars. Easier is Uranus, which glows at magnitude 5.7 near Phi Aquarii. Mars has brightened to magnitude 0.3. It will pass south of the Pleiades early in the month.

The Moon and Mars stand near the Pleiades on the morning of August 7. August 1 Mercury passes 6 degrees from Pollux. August 3 Moon is at perigee, 229,218 miles from Earth, 7:54 p.m. August 5 Last-quarter Moon at 5:20 p.m. August 6 Moon passes 6 degrees from Mars. August 12 New Moon at 7:03 p.m. August 13 Perseid meteor shower peaks (see abov e); Neptune is at opposition. August 20 First-quarter Moon at 7:54 p.m. August 21 Moon lies near Jupiter and Antares. August 23 Mars lies 5 degrees from Aldebaran. August 28 Full Moon at 6:35 a.m.; total lunar eclipse (see above). August 29 Asteroid 4 Vesta passes half a degree from Jupiter. August 30 Moon is at perigee, 226,296 miles from Earth, 8:12 p.m.

Jovian Belt Fades, Venus and Saturn Rendezvous
By Joseph A. Fedrick
I joined several AAA members on the Brooklyn Promenade June 30 to watch the conjunction of Venus and Saturn. Four telescopes and two pairs of binoculars were available. At least 100 people viewed the planets.
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I first spotted Venus through a break in the clouds and then saw Saturn as I used an 8-inch SchmidtCassegrain that was set up. Venus was a spectacular crescent while Saturn, barely in the same field of view at low power, was a pale yellow orb with slightly tilted rings. The rings seemed to slant downward toward the Fedrick continued on page 11


A Message from AAA President Richard Rosenberg
Hello, members: I hope you have been enjoying yourselves this summer, and that your enjoyment has included a few trips to places with a dark night sky. I've just returned from a trip to Lake Taghkanic State Park in Columbia County, 100 miles north of New York City. With me were AAA members John Swierzbin, Marcelo Cabrera, Stephen Shainbart and Mark Baratta, as well as a few other sky lovers. We had a constellation tour via laser pointer, hunted Ganymede 's shadow on Jupiter and feasted on globular and open-star clusters, but the most awesome sight of all was a galaxy visible to the naked eye.

Yes, I'm speaking of our very own Milky Way. The detail that can be seen when far from city lights is just amazing. Check out the Great Rift, a dark region from Cygnus to Aquila dividing the Milky Way into two parts. Look at the great star clouds in Sagittarius and Scutum. (You don't need to know where the constellation Scutum is--just follow the Milky Way and enjoy.)
AAA member Tom Haeberle and I are planning an observing session weekend of August 11-12. The Moon won't be present, so the sky will be of the Perseid meteor shower. Let me know if you're interested. If you're town list. Just send an email to me at outoftown@aaa.org and I'll let you not on line, give me a call (my number is below). in the Catskills near his dark. Sunday night will online, the easiest way know of any events bei country home on the also feature the peak is to join my out-ofng planned. If you're

Looking into the fall, our 2007-08 lecture series kicks off October 5 at the AMNH. Mario Livio, senior astrophysicist at the Hubble Space Telescope Science Institute and previous head of the Institute's science division, will discuss the achievements of the Hubble. Our lecture chairman, David Kraft, was putting the finishing touches on our lectures last month. See next month's Ey epiece for the details on what promises to be an exciting group of presentations. Rich Rosenberg, AAA President, pr esident @a a a .or g, (718) 522-5014

Dark Matter continued from page 1 of how dark matter evolved over the history of the universe. This is possible due to the finite speed of light. The distance, and therefore age, of a galaxy is determined by measuring the redshift of its spectrum. By splitting the half million background source galaxies it observed into discrete redshift bins, Massey's team could visualize a three-dimensional map of the dark matter surrounding them. For research details, see the January 2007 N ature article, "Dark Matter Map Reveals Cosmic Scaffolding." When this image was unveiled at the talk, we suddenly found ourselves face to face with blobs of dark matter that looked like the voids and interconnected ma-

terial of a coral-reef sponge on a cosmic scale. There are voids of space in which there's nothing at all. Around the voids are tangled strings of dark matter that form a scaffold. Ordinary matter falls into this scaffolding and builds up into galaxies and clusters. With a lead time over ordinary matter, dark matter starts to collapse before ordinary matter does. Clumps of dark matter are found where there are clumps of ordinary matter. It has been a vital element in the formation of the universe. Unable to hide from these new techniques, the invisible is becoming visible and pointing us to more questions and greater technological challenges. To download Massey's full presentation, go to http://www.astro.caltech.edu/~rjm/publicity/.
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What Can Amateurs Play in NEA Search Endeavors?
NASA was asked in December 2005 to study the options for extending the Spaceguard Survey of small nearEarth asteroids (NEAs) down to asteroids 140 meters in diameter, with a goal of achieving 90% completeness by 2020. NASA recently posted its reply. "One of the sometimes confusing elements of the subsequent discussion concerns the role of amateur astronomers in future NEA surveys," notes David Morrison, an NEA/NEO maven at NASA. scope and expand to four in the next few years. "Because these instruments will discover many more NEAs than the current Spaceguard (about a factor of 20 per night), there's little prospect for this same approach to follow-up astrometry, using amateur or professional telescopes. Therefore LSST and PanSTARRS are planning their own follow-up automatically, by acquiring enough images over a long enough time to yield adequate orbits with their data only."

"Amateurs are playing a unique and indispensable role in the current Spaceguard Survey, primarily by making the astrometric (positional) observations of recently discovered NEAs that are necessary to define orbits," he says. "In a few cases they have also contributed in searching for pre-discovery images, which are often critical for getting a good enough orbit to assess the probability of impact."
The next-generation Spaceguard Deep Survey, probably based on the LSST and PanSTARRS telescopes, will discover asteroids at substantially fainter magnitudes, typically V=23-24," Morrison notes. The LSST (Large Synoptic Survey Telescope), an 8-meter wide-angle survey instrument, should start observations in 2013. PanSTARRS will start with one 1.8-meter tele-

In its report to Congress, NASA suggested amateurs might still be able to contribute by searching for prediscovery images, Morrison says. "It's not clear to me what's contemplated, since the [LSST and PanSTARRS] surveys will be best able to search their own archival data, but maybe they'd welcome volunteer help. It seems unlikely, given the small size of most discovered asteroids, that there will be many prediscovery images to find in other databases."
Don Yeomans, manager of the NASA/NEO program office at JPL, asserts that "The report...contains unrealistic expectations about amateur astronomers' ability to follow-up on new deep surveys, which will find NEAs that are mostly too faint to be reached with amateur telescopes."

Internet Volunteers Are Sought for Detailed Galaxy Research
Scientists need help sorting through an unusual digital photo album: pictures of about 1 million galaxies, the Associated Press reported last month. They're asking volunteers on the Internet to help classify the galaxies as elliptical or spiral and note, where possible, in which direction they rotate. It would be the largest galactic census ever compiled, something scientists say would provide new insight into the structure of the universe. Astronomers say computer programs have been unable to reliably classify the star systems. "We have more data than we can assimilate, and we need help," said Bob Nichol, an astronomer at the University of Portsmouth in England. Without volunteers, researchers would need years to wade through the photographs, which were taken auto4

matically by a massive digital camera mounted onto a telescope at the Apache Point Observatory near Sunspot, N.M., Nichol said. With 10,000 to 20,000 people working to classify the galaxies, the process could take as little as a month. Volunteers would sign on to the Web site, www.galaxyzoo.org., complete a brief tutorial and pick through one galaxy after another. The galaxies would be identified by several people to guard against errors and pranks, and scientists would decide any disputes. The catalog would help researchers understand how galaxies form and interact. "At some level, what we learn about these galaxies could tell us something quite fundamental about cosmology and particle physics,'' Nichol said.


Review: Designing an Unconventional Lunar Mission
By Katherine Avakian
In 1990, Edward Belbruno, a specialist in theoretical celestial mechanics, who had worked at JPL as a trajectory designer, got an S.O.S. asking his help in salvaging a Japanese space mission gone awry. The Japanese had launched two robotic spacecraft attached to each other into Earth orbit. The smaller spacecraft detached, and en route to the Moon, got lost. The other, Hiten, very low on fuel, was neither meant nor built to go to the Moon. But Japan, for reasons of national pride and prestige, wanted to somehow get Hiten to the Moon. How Belbruno accomplished this is explained in the very readable book, "Fly Me to the Moon" (Princeton University Press, $19.95). His style is informal and explanatory, and the book's many hand-drawn illustrations clarify its subject matter. Topics include a new theory on how the object, now the Moon, amassed its mass before smashing into the early Earth; how Jupiter's gravitational field can cause comets to transit from their orbits into other, possible Earth-crossing orbits; and his explanation of chaos, which he says results from the "subtle intermingling of the gravitational pulls and tugs on an object moving in space." Belbruno left a post as assistant professor in mathematics at Boston University and joined JPL in 1985 to work on the Galileo mission to Jupiter. He soon became aware of the cultural difference between academicians and aerospace engineers. "My training was more concerned with the theoretical ways objects can move in space....They were interested in getting a spacecraft to a specific planet." NASA's method for getting a spacecraft into lunar orbit was a Hohmann transfer. After a rocket launches a spacecraft into Earth orbit, the spacecraft fires its engines for a few minutes to send it to the Moon. In about three days it reaches the Moon and, at the proper altitude, the spacecraft turns around and fires its engines to slow down so it can achieve lunar orbit. While the Hohmann transfer is relatively fast, Belbruno notes it's expensive. For instance, a typical small robotic spacecraft with a mass of 2,200 pounds would require about 528 pounds of fuel to accomplish lunar capture. At a cost of $250,000 per pound, this capture maneuver alone would cost $132 million. Belbruno got a chance to work on finding a lowcost route when asked to design a lunar mission for a very small spacecraft using unconventional rockets. The project was named the Lunar Get Away Special (LGAS) because the spacecraft would fit into a trash can-sized container in the shuttle cargo bay and be released after the shuttle reached Earth orbit. Its engines also were different. Standard rockets ignite chemicals, creating a high thrust for a few minutes, dramatically changing the speed of the spacecraft. LGAS, on the other hand, would use ion engines. They work by passing a gas, xenon, through high voltage-producing xenon ions, which are then accelerated out of an opening, creating a small thrust. Although the thrust of an ion engine is 30,000 times weaker than a chemical rocket, it can run continuously. On the computer, Belbruno started at the endpoint, the desired location for LGAS near the Moon, and plotted the trajectory backward. Then in forward time, the spacecraft would follow the computed path, slowly spiral up from Earth orbit, coast to the Moon, and slowly spiral down to go into lunar orbit. Because its ion engines have a vastly weaker thrust than standard rockets, the journey would take two years, so this would be prohibitive for human transport. However, it could be used to move supplies and machinery cheaply to a Moon base since it would be done without the use of fuel. NASA also has plans for low-energy routes between Jupiter's moons. The rescue of Hiten was the first time Belbruno could apply his work to a real spacecraft. As with LGAS, he used the same method by starting at the point near the Moon where Hiten should end up and plotting a path backward. On April 24, 1991, Hiten's engines gave it a small boost to leave Earth orbit, and with a gravity assist from the Moon, Hiten traveled the route plotted for it, arriving at the Moon 150 days later, having used only 6.6 pounds of the 15.4 pounds of hydrazine fuel available. Several of Belbruno's trajectories have been patented, with others still pending. In 1997, he formed Innovative Orbital Design, of which he is president. He also is visiting research collaborator at Princeton University's Department of Astrophysical Sciences.
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Briefs: Raging Martian Dust Storm Cuts Power to Rovers
A raging dust storm on Mars cut power to NASA's twin rovers to dangerously low levels, threatening an end to the mission. The storm, which has been brewing for nearly a month, is blocking 85%-90% of all sunlight to the surface. Opportunity and Spirit rely on sunlight to charge their solar panels. The storms might continue for several weeks. The brightness of the Sun as viewed from the surface is down to under 5% of what it would be with a perfectly transparent atmosphere. The rovers' scientific operations were stopped July 18. When dust reduced the solar panels' output sharply, driving and most observations were suspended. Opportunity is experiencing the brunt of the storm. Scientists for the Phoenix lander, which launches August 3, say the only way such dust storms could seriously harm their spacecraft would be if one were to suddenly whip up during descent. Like the rovers, Phoenix will power its electronics using sunlight harvested by solar panels. The lander will touch down on Mars' water-ice-rich north polar region to drill for clues about Mars' geological, and perhaps biological, history. Scientists have discovered the imprints of water vapor in starlight filtered through the atmosphere of a giant gas planet. Combined with a study announced earlier this year, this provides evidence that extrasolar planets are as rich in water as worlds in our solar system. HD 189733b belongs to a class of gas giants called hot Jupiters, which orbit their stars from a distance closer than Mercury is to our Sun. The fiery world is 15% bigger than Jupiter and orbits a Sun-like star 64 light-years away in Vulpecula, the Fox. Its average temperature is 1,340 degrees and it orbits its star in just two days. Astronomers have found evidence for the most distant galaxies ever detected. They're seen as they existed 500 million years after the birth of the universe. Their light was seen only because it was distorted in a natural gravitational lens created by the gravity-bending mass of a nearer cluster of galaxies. By looking through carefully selected clusters, astronomers located six star-forming galaxies at unprecedented distances. Light from the galaxies was boosted about 20 times by the magnifying effect of the foreground galaxy cluster. The galaxies show an era soon after the first stars formed. Life as we know it on Earth isn't the only kind possible in the universe, a National Academy of Sciences
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report said. The fact that all life here is linked by a common heritage can be a handicap in finding life elsewhere since it could be unrecognizable. There's concern that researchers have limited their thinking about extraterrestrial life. The assumption that life requires water, for example, has limited the search for life on Mars to habitats where liquid water is thought to be present or once flowed. Recent research suggests liquids such as ammonia or formamide could be alternatives to water for some organisms. For this reason, the report urges increased priority for a follow-up mission to Titan, a world covered in liquid water-ammonia mixtures. Research also suggests alien life might use something other than DNA to encode genetic information. The report recommends future searches for life include instruments to detect lightweight chemical elements--such as carbon, hydrogen, oxygen, phosphorus and sulfur--in addition to complex organic molecules found in terrestrial organisms. Mars once had a propensity for juggling its polar ice caps from one end of the planet to the other. A perennial wobble in Mars' tilt pushed one pole closer to the Sun, causing water ice to evaporate and refreeze at the colder pole. Every 51,000 Martian years, the wobble would bring the colder pole closest to the Sun and shuffle the ice cap back to the opposite pole, new research shows. It's unknown what stopped the cycle. Frozen carbon dioxide helped drive the cycle. As the Sun evaporated water ice from the warmer pole, vapors eventually made their way to the opposite pole. Once the water reached the sheet of dry ice, or frozen carbon dioxide, it refroze there. In this way, Mars' water ice slowly migrated to the cooler pole. The best explanation for the cycle's end is that a thick slab of frozen carbon dioxide capped the water ice below it in Mars' southern pole. Two galaxy clusters have been spotted colliding at what was earlier thought to be impossibly high speeds. Astronomers estimate the collision involves clusters, each containing hundreds of galaxies, colliding at over 7 million miles per hour. Researchers have spotted blobs of gas ejected from the cores of the clusters, which will eventually fall back and merge together. Hubble images of Ceres and Vesta reveal and other features that will be targets of close-up vations by NASA's Dawn spacecraft. Dawn's Briefs continued on craters obserthricepage 7


Briefs: Can We Actually See the Cosmos Pre-Big Bang?
Briefs continued from page 6 postponed launch is now set for no earlier than September. Dawn will be the first mission to launch a probe to Ceres and Vesta. Dawn will orbit Vesta in October 2011. After a mapping mission, it will move on to Ceres by February 2015. Hubble's picture of Ceres reveals bright and dark regions that could be topographic features such as craters, or could show areas of different surface material. Ceres' round shape suggests its interior is layered. It might have a rocky core, an icy mantle and a thin dusty crust. There could be water inside. The picture of Vesta allowed mapping of its southern hemisphere. A crater there, caused by an ancient collision, is 285 miles across. Color differences in the image reflect differences in surface chemicals, some possibly due to volcanic activity. One of the world's largest and most powerful telescopes turned its 34-foot wide mirror toward the skies on one of Spain's Canary Islands last month. Twelve of the telescope's eventual 36 mirrors aimed at a twin star close to the Earth's northern axis, near the North Star. Twelve images merged into one as the telescope focused. The $179 million Great Canary Telescope (GCT) atop La Palma should be fully operational by May. It will reach the weakest and most distant celestial objects. It will bepossible to capture the birth of new stars, to study more profoundly the characteristics of black holes and to decipher chemical components generated by the Big Bang. The GCT's size is akin to the new Southern African Large Telescope and the Hobby-Eberly telescope in Texas, both with 36-foot mirrors. Image analyses suggest the odd appearance of Saturn's moon Hyperion is the result of a highly porous surface that preserves craters to remain nearly as pristine as when they were created. Scientists concluded Hyperion is mostly water ice and its crater bottoms are covered in a dark red sludge that could help resolve some of the moon's other strange properties. Oval-shaped Hyperion, one of the largest non-spherical bodies in the solar system, is 250 miles at its widest point. Unlike most of Saturn's moons, it's not tidally locked to the planet. Hyperion undergoes chaotic rotation; its rotation axis shifts so much that scientists can't predict its orientation in space. Most of its hundreds of craters average 1-6 miles wide. Hyperion's surface is so brittle an object striking it will create a hole but send no material flying. The moon's dinginess is believed caused by a dark, organic material littering the surface and concentrated in several craters. Astronomers have dissected the dusty, gassy layers of the red giant S Orionis, a star that pulsates in size from a diameter roughly equal to the orbit of Mars to halfway between Mars and Jupiter every 410 days. No study of a red giant has been done looking at infrared and radio-wave views simultaneously. S Orionis sheds about the mass of Earth each year. Much material escapes from its gravity and begins to form planetary nebulas. But gravity overcomes a lot of gas and dust that gets pulled back into the star, restarting the cycle. Where those layers are and what they're made of was a mystery until the new investigation. The team measured shells of gas and dust surrounding the star to the most detailed level to date, discovering the star's dusty shell of the compound corundum was twice as large as thought. It may be possible to glimpse into the universe prior to the Big Bang, researchers say. To see how far one might gaze, a physicist ran calculations based on loop quantum gravity, one of a number of theories seeking to explain the universe's underlying structure. Past research suggested the Big Bang was preceded by infinite energies and space-time warping where existing scientific theories break down, making it impossible to peer beforehand. New findings suggest that although levels of energy and space-time warping before the Big Bang were incredibly high, they were finite. Scientists could spot clues in the present of what the cosmos looked like previously. If evidence of the past persisted after the Big Bang, its influence could be spotted in astronomical observations and computational models. However, some knowledge of the past may have been irrevocably lost. These findings differ from a cyclic model of the cosmos by Princeton's Paul Steinhardt and Cambridge's Neil Turok, which says an infinite series of Big Bangs preceding our universe were caused by additional branes perpetually colliding and bouncing off each other. Black holes aren't the only objects that spew powerful jets from their poles. Dead, smoldering stars can Briefs continued on page 8
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Briefs: Dead Stars, Like Black Holes, Can Emit Powerful Jets
Briefs continued from page 7 emit them, and the jets might surpass black holes'. So unusual properties of black holes, such as an event horizon and no surface, aren't required for jets to form. Scientists spotted a jet 20,000 light-years away in Circinus X-1, a system where a neutron star orbits a normal star several times the Suns' mass. This is the first extended X -ray jet associated with a neutron star. Scientists estimate a surprisingly high percentage of energy created by material falling onto the neutron star powers the jet. Slushy geysers on Charon apparently coat it in ice crystals. Water likely trickles very slowly, repaving Charon in a thin layer of 1-millimeter-deep ice every 100,000 years. Astronomers learned of the deposits after discovering spectral fingerprints of ammonia hydrates and water crystals in light coming from the moon. If Charon's ice were left over from the solar system's birth, it would have lost the crystalline structure due to bombardment by cosmic rays and ultraviolet radiation from the Sun. If the ice had been caused by meteorite impacts, a different set of chemical fingerprints would be seen. Scientists have successfully coated a liquid surface with a thin layer of silver metal, creating a highly reflective mirror that could be used to create huge liquidmirror telescopes on the Moon. They could be as wide as a football field, letting scientists peer back to when the first stars were born. Researchers applied the silver film layer to the surface of a fluid that consists only of ions. A lunar liquid-mirror telescope under consideration by NASA could detect objects up to 1,000 times fainter than could the James Webb Space Telescope, a nextgeneration orbiting observatory to launch in 2013. Two stellar explosions went off just weeks apart in the same galaxy, the first time two supernova events have been observed in a galaxy so close in time. The blasts occurred in a galaxy 380 million light-years away in Hercules that hadn't been known to host a supernova. The blasts were triggered in different ways. Supernova 2007ck, spotted May 19, was a Type II event, when the core of a massive star runs out of nuclear fuel and collapses under its own gravitational weight. Supernova 2007co, observed June 4, was a Type 1a event, when a white dwarf star siphons off so much material from the
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surface of a companion star that it blows up. Clouds on Jupiter have swapped places, changing their shapes and colors as lower clouds move up and higher clouds sink. Jupiter is wrapped in cloudy strips of yellows, browns and whites, created by winds at various latitudes blowing in different directions. High-elevation clouds reside in belt regions of the atmosphere. Belt clouds are darker than those in relatively low-elevation regions. Winds in belts and zones flow in opposite directions. Hubble witnessed zones darkening into belts, and belts lightening and transforming into zones. Clouds rapidly changed shapes and sizes. Images show a thin band of high-elevation clouds above Jupiter's equator sinking through the atmosphere and turning brown. The clouds also morph from small squiggles to large wave-shaped features. Below the equator, a giant tan-colored cloud disappears, making way for many white swirls. Engineers are studying whether to shut Arecibo, the world's largest radio telescope, which faces steep budget cuts. Fears that it could face extinction began last year, when an NSF-commissioned panel called for deep budget cuts and said officials should consider eliminating it at decade's end. The new study doesn't mean the complex will close entirely, at least not immediately. The telescope's budget will plummet from $10.5 million this year to $4 million by 2010, with savings going to build a telescope 20 times more powerful. Arecibo is receiving a makeover to persuade officials to keep it open. China plans to launch a lunar orbiter in the second half of 2007, the first step towards a lunar probe. Next would be an attempt to land. A rover mission in 2012 would collect samples. China, which plans a space walk by 2008, will continue manned space missions, and would also attempt docking vessels. South Korea said it will push for exploration of planets by 2017. A study of microbes in China's remote deserts could help astrobiologists refine maps for uncovering Martian life. The study was the first based on a combination of extreme cold and dryness. Scientists chose three sites based on temperatures and rainfall. Ecologists suspect microbes can live within rock pores or beneath Briefs continued on page 12


Tyson Expansively Discusses Mysterious Black Holes
In a recent interview with space.com, Hayden Planetarium director Neil deGrasse Tyson discussed black holes. Excerpts from his answers follow. A black hole is a region of space where so much matter is crammed into it that the gravity is so high that not even light can escape it. There are two broad categories of black holes. One is the monstrous black holes we find in the centers of galaxies. Those could be up to a million times the mass of the Sun, and we don't completely understand how they form. But best data tell us we have one in the middle of every galaxy. Then there's a much smaller kind, in some ways more dangerous, that is the end product of the life of a star. Those could be in your way as you journey across the galaxy since you can accidentally stumble on it. The ones we know about are rendered visible because they happen to be next to another star where they orbit each other in space and that other star in many of these cases is losing its outer gaseous material. In a way it's getting flayed by the gravity of the black hole. Gas from the nearby star spirals down the hole. As it spirals down, it begins to glow just before it's lost forever. All the black holes we know about around the galaxy are made visible by this process. There are black holes that spin and black holes that don't spin at all. The two broadest categories are simply the black holes that come from the death of a star and the kind you find in the centers of galaxies. If you're the one who took this one way trip [jumping into a black hole], as you descend towards its center you begin to feel the strength of gravity increase at your feet compared with the gravity at your head. The difference in gravity becomes so great that your body initially stretches a little bit. The stretching sensation reaches a point where the strength of the difference in gravity becomes greater than the strength of the bonds or the molecules that hold your flesh together. Not only [will you turn into infinite pieces], it's worse than that because the very fabric of space in the vicinity of a black hole is like a funnel. So as you fall toward a black hole, you're being funneled through the fabric of space. A couple of years ago, Stephen Hawking demonstrated that all information that falls into a black hole is recoverable. So the black hole doesn't lead into someplace else where things exit. The gravity field of a black hole is so intense particles can pop into existence from the energy of that field. You can actually escape a black hole. The particle isn't rising up from the center and crossing the black zone and coming into our universe. The energy field is created by the black hole's gravity and that gravity is created by the matter it's eaten throughout its life. Every time the field produces a particle, the black hole weighs less. Black holes are such an exotic expression of gravity that there are gravity detectors being built to try and detect when things happen in the vicinity of a black hole, such as if a black hole eats a star or if two black holes collide. One way to observe that is what material is doing in the vicinity of a black hole: Is it giving off light? Do we have a telescope that can detect the light? More than] light emanating from it, it's sort of gravity waves. There's no obvious way to see black holes directly. But if they don't have something feeding them material, one way to know they're there is how they distort the path of light from objects behind that's trying to pass through. You might be able to detect one headed your way simply by distortions of the background galaxy. The biggest uncertainty [about black holes] is laws of physics that say the material that became the black hole continues to collapse to a point that's infinitesimally small in the center. No matter how large it started out, there are no known laws of physics that would resist the strength of that gravity to collapse. To say it's infinitesimally small would mean that it has infinite density. You put any amount of matter in a small volume, it gets more and more dense. I want to know what's happening at the center of the black hole. There's a word for it, the singularity. That remains a mystery, and string theorists are kind of in business to solve that.
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Amateurs Indulge Hobby through Astronomy Communities
In June, a New Yor k Times article by Maria Finn highlighted amateur astronomers who have set up dark sky communities. Excerpts follow. Amateur astronomers, frustrated by the artificial light that obscures the stars over most urban and suburban backyards, have learned to chase the darkness to remote areas--not only for star parties and brief trips but to build second homes where they can indulge their hobby at length. If the house can be in a community of likeminded aficionados of dark skies, so much the better. Bill Williams, a pathologist in Boca Raton, Fla., and his wife are building a second home and two observatories on a lot they bought among a cluster of astronomy lovers near Chiefland, Fla. The community at Chiefland was, its residents believe, the first astronomy village. It began in the 1980s when amateur astronomer Billy Dodd retired and traveled with his wife through Florida, looking for skies that offered the clearest views of the stars. They found what they were looking for three hours north of Tampa Bay, in a little-populated area near the Gulf of Mexico. They bought 40 acres south of Chiefland, a town of about 2,000 people, and Dodd built an observatory. As years passed, he wanted some company, so he subdivided his property and sold it to other amateur astronomers, creating Chiefland Astronomy Village, an enclave where property owners agree to observe darksky rules. Chiefland's fame grew when one buyer, Tom Clark, purchased five acres and turned three into a communal field for stargazing. Up to 300 people gather in Clark's front yard for star parties, some weeklong events. As the star parties grew, more amateur astronomers sought property in Chiefland, buying in Dodd's original subdivision of 12 lots and nearby. There are now about 20 "astroresidents" of the village. Technological developments in the 1990s made digital imaging of the sky practical for amateurs. Now, rather than look through a telescope, many stargazers use cameras that transfer images onto computer screens. Says Williams, "I need one roll-off-roof design for work10

ing with multiple telescopes at once, and a separate dome observatory for imaging purposes with a larger scope." That observatory will be usable at long distance, via a computer connection, from his home in Boca Raton. Jack Newton, a former resident of Chiefland, and fellow stargazer Gene Turner superimposed a NASA dark-skies map over a road map of Arizona in 2002 and drove toward the darkest region they saw. Newton, a retiree who in the summer operates an astronomy-themed bed-and-breakfast in Osoyoos, B. C., and Turner, a developer, were looking for a place to start an astronomy community. They wound up in the southeast corner of Arizona about a mile outside Portal, a town of about 100. They secured 450 acres in front of Cave Creek Canyon in the foothills of the Chiricahua Mountains and founded Arizona Sky Village, a development with darksky covenants that will eventually have 85 lots. Joe Morris, a doctor who lives in Maryland, took up astronomy in the 1980s. He bought a telescope and built an observatory, but light from Baltimore and Washington encroached on his view. In the sky village, he wired up a robotic observatory that will let him watch the Arizona sky on his home computer in Maryland. Most people with houses at Arizona Sky Village bought them prefab and had them shipped. Also planned are 11 houses with fractional ownership. These will have high-speed Internet access, remote telescope links and 14 -inch computerized telescopes. There will be a communal observatory and a weeklong annual star party. Another astronomy subdivision, Deerlick Astronomy Village, has been developed 120 miles east of Atlanta. Chris Hetlage, an amateur astrophotographer from Atlanta, looked for the darkest place in Georgia and was welcomed in Taliaferro County. "They didn't want a lot of growth, we are low profile, so it was a good match." The owners developed a large observing area where nonresidents can purchase yearly memberships for $35. Part of the field was sold to the Atlanta Astronomy Club, which holds its big event, the Peach State Star Gaze, annually at Deerlick.


Events on the Horizon August 2007
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 Check the AMNH's website at www.amnh.org for an additional listing of other events. Tuesday, August 7, dusk to 10 p. m. Observing at Cadman Plaza, Brooklyn, P, T, C Next date: September 4 Thursday, August 9, 6:30 to 8:30 p. m. Recent Advances in Astronomy Seminar, M, HQ Next date: September 20 Saturday, August 11, dusk Stargazing, Great Kills Gateway National Park, Staten Island, Perseid Meteor Shower, P, T, C At the model airplane field. Next date: September 15 Saturday, August 11, dusk Upper Manhattan Observing, P, T, C Inwood Park, 218 Street and Indian Road. Next date: September 8n Saturdays, August 11 and 18 Observing at Anthony Wayne Recreational Area near Bear Mountain, P, T. C For directions, aaa.org. Next dates: September 8 and 15. Saturday and Sunday, August 11 and 12 Dark-Sky Stargazing, M, T A club observing event for both nights to see the Perseid meteor shower and the summer sky from a very dark site in the Catskills. See president's message on page 3. Saturday, August 11, 9:30 p. m. to midnight Custer Institute, Southold, N. Y. Perseid Meteor Star Party, P, T, C More info: www.custerobservatory.org/. Wednesday, August 15, 7 p. m. AAA quarterly board meeting, M, HQ All members are invited to attend. Wednesday, August 22, dusk Stargazing at Prospect Park, Brooklyn, P, T Observing in the Long Meadow. Gathering is tentative; check www.aaa.org or Ron McCullough, 718-499-4567. Friday, August 24, 7 p. m. Stargazing, Carl Schurz Park, Manhattan, P, T, C Next date: September 28 Saturday, August 25, 10 to noon Central Park Solar Observing, P, C Conservatory Waters. Next date: September 29 Saturday, August 25, 1 to 4 p. m. Observers Group, M, HQ Next date: September 29 Fedrick continued from page 2 Venusian crescent and Saturn's moon Titan appeared as a faint dot of light.

Contacting the AAA
If you want to join, volunteer your time, participate in events, have a question or need to change your address, e-mail secretary @aaa.org, or leave a message at AAA hq: (212) 535-2922. Also, visit us on the web at www.aaa.org. If you're interested in writing an article for Ey epiece, contact editor Dan Harrison at editor@aaa.org or (914) 762-0358.

Later, when a couple of scopes were pointed at Jupiter, we saw its South Equatorial Belt was barely visible because it had faded so much. I later got an e-mail from someone who noted there have been spectacular changes in Jupiter's belts lately. On subsequent nights I used my 6-inch reflector to note that the South Equatorial Belt was still faded. I look forward to seeing more from this ever-dynamic planet.
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Briefs continued from page 8 translucent rocks where moisture's most likely to remain. An increase in rainfall was associated with a spike in microbial density, but there were other factors, such as effects of temperature, humidity and light. Certain factors make microbial life more likely in these harsh deserts. One is rock size, with larger rocks supporting more bacteria, probably because they can store more water. The skies of stars might experience weather like that on planets. Drifting clouds are wispy except they're made of mercury. Investigating these clouds might shed light on how elements form inside stars. Scientists spent seven years looking at alpha Andromedae, the brightest star in Andromeda. It's not magnetic, so spots discovered five years ago were an enigma. Now researchers have found the spots are clouds that form and disperse in the star's skies. Such weather could be seen on stars that are hot and massive. They also have to spin relatively slowly since spinning too fast might destroy clouds. What makes these metal clouds form? Possibly random disturbances in alpha Andromedae's atmosphere or the gravitational pull of alpha Andromedae's companion star. Discovery of star weather could help explain discrepanAmateur Astronomers Association 1010 Park Avenue New York, NY 10028

cies in levels of mercury and other heavy elements. Researchers think they've found a smoking gun for the 1908 Tunguska explosion in Siberia: the 164-footdeep Lake Cheko, just 5 miles northwest of the epicenter of destruction. At the bottom, they measured seismic waves reflecting off something. Nobody had found this before. They explain that and the shape of the lake as a low-velocity impact crater. To find out if it's an impact crater, a core sample 33 feet into the bottom is needed to investigate a spot where the team detected a "reflecting" anomaly with seismic instruments. This could be where the ground was compacted by an impact or where part of a meteorite lies. The object, if found, could be more than 30 feet in diameter and weigh almost 1,700 tons. A forest fire has led to a chance discovery of debris from a meteorite impact 1.85 billion years ago. Geologists had scheduled a field trip in northeast Minnesota, but most areas they wanted to explore were closed because of a wildfire. A geologist scouting new locations stumbled across debris linked to an impact in Sudbury, Ont. That impact created a crater more than 150 miles across, scattering rock and dust over nearly a million square miles. This is the second-oldest and second-

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