Really Rocket Science

This Saturday, May 6th, is the 33rd Annual National Astronomy Day, and events are being held all around the country: 

Astronomy Day is a grass roots movement designed to share the joy of astronomy with the general population – "Bringing Astronomy to the People."  On Astronomy Day, celebrated this year on Saturday, May 6, thousands of people who have never looked through a telescope will have an opportunity to see first hand what has so many amateur and professional astronomers all excited.  Astronomy clubs, science museums, observatories, universities, planetariums, laboratories, libraries, and nature centers host special events and activities to acquaint their population with local astronomical resources and facilities.  Many of these events are located at non-astronomical sites; shopping malls, parks, urban centers-truly Bringing Astronomy to the People.  It is an astronomical event that helps highlight ways the general public can get involved with astronomy – or at least get some of their questions about astronomy answered.

Astronomy Magazine has a partial list of events around the country. If you know of events near you, please post them in the comment threads. 

Everybody’s talking about the big break-up. No, I don’t mean Nick and Jessica. I’m talking about Schwassmann-Wachmann, a comet that supposed to swung by earth next month, after it — according to one report — broke up for no apparent reason ten years ago. 

In 1995, Comet 73P/Schwassmann-Wachmann 3 did something unexpected: it fell apart. For no apparent reason, the comet’s nucleus split into at least three "mini-comets" flying single file through space. Astronomers watched with interest, but the view was blurry even through large telescopes. "73P" was a hundred and fifty million miles away.

No apparent reason? Not exactly. 

Naturally, I’m not the guy with the answers on this. (Again, I refer you to the screen name.) But Phil over at Bad Astronomy has what seems like a reasonable explanation to me. 

The exact cause is a mystery, though there are plenty of reason why a comet would fall apart. Comets are made of rock and ice. When they get near the Sun, the ice sublimates– turns directly into a gas — and flows into space, which is why comets look fuzzy in pictures. The actual nucleus, the solid part, is very small, but the coma, the fuzzy part, can be thousands of miles across.

It makes sense that after repeated passes of the Sun, enough ice is lost to venting that the structure of the comet can be fragile, since the ice in a way is holding the comet nucleus together. Once enough ice is gone, a breakup could occur if the sublimating ice builds up enough pressure to disrupt the structure. But that is just one explanation. The famous comet Shoemaker-Levy 9 broke apart because of the immense tidal forces of Jupiter’s gravity. Most comets don’t break apart; look at comet Halley, which has been circling the Sun for a long, long time (it was seen in ancient times). It goes to show that some comets are very fragile, and some are not.

OK, so it’s just one possible explanation, but it’s one more than I could come up with on my own. But just for the sake of argument, what other explanations could there be? Unless Bruce Willis or Morgan Freeman had an hand in it, I’ll take Phil’s explanation for now. (HubbleSite has the pics.)

The European Space Agency released their first images from the Venus Express mission, including our first view of the south pole.

As reported by the AP’s Melissa Eddy in The Sun Herald (Biloxi, Miss.):

"We can see there is a swirl here that is similar to the one we know from the north pole," said Horst Uwe Keller, who leads the team operating the craft’s wide-angle camera – one of seven instruments aboard the Venus Express.  

Using infrared technology that allows the camera to peer though the clouds, scientists hope to be able to determine how the sulfuric acid that swathes the planet was formed, and pinpoint the cause of the high-speed winds that sends it swirling in massive clouds.

 

The ESA has some really cool images and 3-D videos on their site, too.

The Planetary Society and Harvard physicist Paul Horowitz pointed a giant telescope at the sky for the first time yesterday, beginning a systematic search for light signals from an alien civilization. Science A-Go-Go reports:

Housed beneath a retractable roof situated high atop a wooded ridge in Harvard, the telescope isn’t what most people would expect when they visualize a powerful optical telescope. But what may look like a mish-mash of metal bars and mirrors to the uninitiated represents a truly ambitious project that would make Planetary Society founders Bruce Murray, Carl Sagan, and Louis Friedman, Executive Director of the Planetary Society, extremely proud….

[T]he powerful 72-inch SETI optical telescope pointed its giant mirror at the sky for the first time on April 11, and began a systematic search for light signals from an alien civilization.

The telescope has some impressive computer muscle behind it, with the developers claiming that it can process the equivalent of all books in print in a second. Its optical detectors are cutting edge as well, with a sensitivity that can detect a billionth-of-a-second flash of light. The formidable technology driving it should allow the new telescope to scan the entire northern hemisphere sky over the course of a year.

The Planetary Society says that the observatory represents the biggest SETI project it has ever sponsored… [D]espite many years of scanning the skies for radio signals, there has been little in the way of any definitive ET activity, hence the Society’s interest in the visible spectrum. "We have been listening for alien signals for decades," said Friedman, "it’s time we started to watch for signals as well."

It is now common among SETI advocates to argue that alien civilizations are just as likely to communicate with light signals as they are with radio waves, and not without good reason, as there are a number of advantages to using light as a form of interstellar communication. Unlike radio waves, a laser-like beam suffers little interference as it travels through space, not to mention the vast amount of data that can be transmitted using such a beam. Additionally, a laser’s unidirectional quality coupled with its brightness – capable of reaching intensities 10 times greater than the sun – make it easier for receivers to both see and track the beam to its source. And aside from the initial outlay, the optical SETI project is simpler, cheaper and will cost far less to maintain than its radio counterparts.

But one of the project’s major strengths is also one of its biggest weaknesses, because unless an extraterrestrial beam is pointed our way it is unlikely that it will be detected. But despite this limitation, the Society are happy that they are now covering yet another possible avenue of communication in their search for alien civilizations.

Friday saw the release of the first color image from NASA’s Mars Reconnaissance Orbiter.

ABC News reports:

The crisp test images released Friday revealed pocked craters, carved gullies and wind-formed dunes in Mars’ southern hemisphere. The diverse geologic features show the importance of water, wind and meteor impacts in shaping the Martian surface, scientists said.

The orbiter, the most advanced spacecraft ever sent to another planet, reached Mars on March 10 and slipped into an elliptical orbit. Over the next six months, it will dip into the upper atmosphere to shrink its orbit, lowering itself to 158 miles above the surface.

Last month, the orbiter beamed back the first view of Mars from an altitude of 1,547 miles. Those first test images were meant to calibrate the high-resolution camera aboard the spacecraft. The latest images were taken at the same time, but scientists spent several weeks processing them.

The Reconnaissance Orbiter will begin collecting data in November, and scientists expect the resolution of those images to be nine times higher.

The image is in infrared color– so the colors seen in this post are not what would be seen by the human eye.

 For additional information on the above image, click here.
 

U.C. Berkeley astronomy professor Imke de Pater tells Red Orbit:

The newly discovered outer ring of Uranus is bright blue, for the same reason the Earth’s sky is blue — it is made up of tiny particles, astronomers said on Thursday.

It is "strikingly similar" to Saturn’s outer ring, which astronomers last month confirmed was probably generated by one of the planet’s moons, Enceladus.

Like Saturn’s ring, the Uranus ring also has a small moon in it, called Mab. But Mab is too small and too cold to be spewing a geyser of ice that contributes to the ring as Enceladus is now believed to be doing.

"The outer ring of Saturn is blue and has Enceladus right smack at its brightest spot, and Uranus is strikingly similar, with its blue ring right on top of Mab’s orbit," said Imke de Pater, a professor of astronomy at the University of California Berkeley, who helped lead the study.

"I think there is no chance that the blue ring is caused by geyser activity," added de Pater, whose report is published in Friday’s issue of the journal Science.

Originally named after King George III of England, Uranus is the 4^th largest planet by mass. Found some animation and images of interest, courtesy of the SETI Institute.

The Cern Courier reports on a grassroots project that utilizes the power of the web– and the unused computing power of personal PCs– to help analyze the interstellar dust particles brought back by the Stardust space capsule in early January:

Finding the tiny interstellar dust particles in the Stardust Interstellar Dust Collector will be extremely difficult. The impacts created by interstellar dust can only be found using a high-magnification microscope with a field of view smaller than a grain of salt….. Stardust@home enables public volunteers to help in this task, which is done more accurately by humans than by any pattern recognition software. After a web-based training session, passing a test and registering, volunteers download a virtual microscope (VM). The VM automatically connects to the Stardust@home server and downloads stacks of images created by an automated microscope at the Cosmic Dust Lab at the Johnson Space Center. Each field can then be searched for interstellar dust impacts by focusing up and down with a focus control. The first images for scanning should become available in April and the project should be completed by October.

For more information on on Stardust@home, click here.

This is a great effort:

Join thousands of other students, families, and educators by participating in GLOBE at Night – an international event designed to observe and record the visible stars as a means of measuring light pollution in a given location. Participation is open to anyone – anywhere in the world – who can get outside and look skyward during the week of March 22-29, 2006! There is no cost to participate in GLOBE at Night. Help us reach our goal of 5000 observations from around the world!

 The National Optical Astronomy Observatory, which is sponsoring the event, also has a cool online tool that allows you to witness the changes in the night sky that result from light pollution.

For more information, download the GLOBE Family Activity Packet PDF (in English and Spanish) or subscribe to the GLOBE email list. 

"The tension is mounting for scientists and engineers of NASA’s Mars Reconnaissance Orbiter (MRO) mission as their spacecraft heads toward a red planet rendezvous today," Space.com reports:

 MRO is expected to enter Mars orbit after a 27-minute maneuver around the planet’s southern hemisphere, completing a seven-month trek. That burn is set to begin at 4:25 p.m. EST (2125 GMT) this afternoon, with MRO swinging back into communications range by 5:16 p.m. EST (2216 GMT).

NASA will broadcast MRO’s Mars approach and orbital arrival live on NASA TV beginning at 3:30 p.m. EST today. You can watch it here. 

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"One of Saturn’s moons, Enceladus, is spewing out a giant plume of water vapor that is probably feeding one of the planet’s rings, scientists said on Thursday," Reuters reports, indicating the potential for biological life on the tiny moon.

NASA made the announcement yesterday, and it quickly became headline news around the world:

The findings, published in the journal Science, suggest that tiny Enceladus could have a liquid ocean under its icy surface which in theory could sustain primitive life, similar to Jupiter’s moon Europa. The plume was spotted by Cassini, a joint U.S.-European spacecraft that is visiting Saturn….

Several moons have been found to have evidence of liquid water and the chemical elements needed to make life, including Europa. But scientists are far more intrigued by the plume itself, a gigantic geyser of water vapor and tiny ice particles.

"It’s basically this giant plume of gas coming out of the south pole of Enceladus," Candy Hansen of NASA’S Jet Propulsion Laboratory in California said in a telephone interview.

"The plume is half the size of the moon. It’s huge," said Hansen, a planetary scientist. "Water is being spewed out of this moon. It solves some real mysteries that we have been struggling with over the years."

Indirect observations had shown the moon, discovered in 1789 by William Herschel, was rich in oxygen and hydrogen. But whether this was because of water was not clear.

Both water vapor and water particles were observed, as well as a smattering of other compounds such as methane and carbon dioxide, the international team of scientists report in a series of papers in Science.

It is possible the plume comes directly from ice, but more likely there is a liquid source, they said. It would have to be under the moon’s surface, which is covered with ice.

"If a wet domain exists at the bottom of Enceladus’ icy crust, like a miniature Europan ocean, Cassini may help to confirm it," Jeffrey Kargel of the University of Arizona at Tucson wrote in a commentary. "Might it be a habitat? Cassini cannot answer this question," Kargel added.

"Any life that existed could not be luxuriant and would have to deal with low temperatures, feeble metabolic energy, and perhaps a severe chemical environment. Nevertheless, we cannot discount the possibility that Enceladus might be life’s distant outpost."

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