Pop! Analysis of the images that Stardust took of Comet Tempel 1 strongly suggest that when Deep Impact hit the comet’s surface it broke open several underground cavities that then burst like balloons.
Every year, as part of its educational and research mission, the Space Telescope and Science Institute in Baltimore, Maryland holds a science symposium that focuses one of the big questions of astronomy, inviting over a hundred scientists to come and give their individual perspectives on the state of the field.
This year’s symposium ended yesterday, and the subject was the mysteries of dark matter. Though I wasn’t able to attend the symposium itself, they held a workshop for journalists yesterday, which I did attend. (You can watch the webcast here.)
So, what is dark matter?
First of all, it isn’t dark energy. Dark energy is that mysterious unknown phenomenon that is causing — on vast scales of many billions of light years — the expansion of the universe to accelerate rather than decelerate. It has nothing to do with the question of dark matter.
Second, no one knows. All that scientists do know is that objects in the outer regions of galaxies as well as the galaxies themselves don’t move at the speeds and directions expected if their known mass and gravity were the only forces influencing them. In order to successfully plot their orbits and motions, astronomers have to add a gigantic halo of extra mass, which they have dubbed “dark matter” because it is unseen, undetected, and completely invisible.
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Scientists have found evidence that a subsurface ocean of water and ammonia exists within Saturn’s moon Titan.
Dark matter: light or heavy?
Later today I will be attending press conference at a symposium on dark matter that is being held this week at the Space Telescope Science Institute in Baltimore. I will post more on this subject then.
Why is the Meathook galaxy lopsided?
An evening pause:
More information on the asteroid “flyby” of Earth this coming November 8.
“On November 8, asteroid 2005 YU55 will fly past Earth and at its closest approach point will be about 325,000 kilometers [201,700 miles] away,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “This asteroid is about 400 meters [1,300 feet] wide – the largest space rock we have identified that will come this close until 2028.”
Space telescopes Hubble and Swift have proven that the debris that suddenly surrounded asteroid Scheila last year was caused by a collision.
Astronomers are considering the merger two space missions to create a new optical/ultraviolet space telescope. The mission would be designed to do both deep cosmology and exoplanet observations.
The two communities would both like to see a 4–8-metre telescope in space that would cost in excess of $5 billion. “Our interests are basically aligned,” says [Jim Kasting, a planetary scientist at Pennsylvania State University]. Such a mission would compete for top billing in the next decadal survey of astronomy by the US National Academy of Sciences, due in 2020.
This story is big news, as it indicates two things. First, the 2010 Decadal Survey, released in August 2010, is almost certainly a bust. The budget problems at NASA as well as a general lack of enthusiasm among astronomers and the public for its recommendations mean that the big space missions it proposed will almost certainly not be built.
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In a paper published tonight on the Los Alamos astro-ph preprint website, astronomers described new observations of Comet Hale-Bopp at a distance of 30 astronomical units, or 2.8 billion miles, from the sun. Their conclusions:
To quote the paper, “Observing Hale-Bopp in a completely frozen state would be extremely important because a thick coma was constantly present during the entire appariation [Ed. the fly-by of the Sun]. The coma obscured the nucleus which was not observed directly. Lack photometric data of the bared nucleus, its size — one of the most important input parameter in activity models — remains uncertain.”
The best images from Solar Dynamics Observatory’s first year in space.
