Wednesday, March 12, 2008

Hale-Bopp sets record: comet still active 26 AU from the Sun!

"Eleven years after its perihelion, comet C/1995 O1 (Hale-Bopp) is still active," we learn in a paper for ApJL: Last October a diffuse coma 180,000 km in diameter was seen, with an integrated brightness of 20.04 mag. "The coma was relatively red at V-R=0.66 mag, which is consistent with that of the dust in other comets. The observed properties and the overall fading in brightness between 10 AU and 26 AU follow the predicted behaviour of CO-driven activity (Capria et al. 2002). This is the most distant cometary activity ever observed."

In other news the mystery of the small impact crater in Peru last September - where no large solid mass should have reached the ground - was discussed at a conference: The strange event could change scientists' thinking about how meteorites act and how other craters on Earth were formed.

• Here is an excellent picture of the Moon's ashen light on Mar. 9, two days after new. • The night launch of Endeavour was big fun for bystanders who saw the shuttle vanish in low clouds from nearby but arcing away from a distance. MECO and ET separation may also have been observed, but interpreting STS observations can be difficult. • Meanwhile no more fragments of USA 193 have been spotted for sure, so they must be pretty small.

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