Astro Bob blog: Awesome asteroid flyby today plus a little contestDramatic asteroid flyby today with fresh images plus star cloud closeups and a chance to win a meteorite
By: Bob King, Duluth News Tribune
Awesome asteroid flyby today plus a little contest
These fresh photos of Lutetia were released late today. The asteroid has gone from a point of light to a new world pocked with craters and furrowed with grooves thanks to superb images taken during the flyby. At right is a closeup view of a crater with scattered boulders perched on its rim and slopes. Credit and copyright: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA
The European space probe Rosetta flew by the asteroid 21 Lutetia (loo-TEE-shuh) at 10:10 a.m. Central time this morning. Rosetta's ultimate goal is Comet Churyumov-Gerasimenko with a planned rendezvous in 2014, but the European Space Agency (ESA) made good use of the long journey to study two asteroids en route. The first was 2857 Steins in 2008.
Lutetia (right) was discovered in 1852 and the 21st asteroid to have its orbit determined. It's in the main belt between Mars and Jupiter along with hundreds of thousands of its brothers and sisters. These planetary building blocks never coalesced into a true planet because Jupiter's powerful gravity stirred the region and prevented the pieces from getting together. Lutetia is 82 x 63 x 47 miles across and like many small asteroids, it has an irregular shape. From Earth, we can glean something of its composition which seems to be a peculiar mix of metal and stony, carbon-rich rock. Rosetta will help us better characterize what materials Lutetia's composed of and how they're distributed across its surface. Astronomers will also be looking for any shreds of an atmosphere, determining the asteroid's mass and density and testing out its scientific instruments in preparation for the comet rendezvous. For much more on the story, including updated photos, please check out the ESA's website and live webcast. The image of Lutetia above is another closeup and shows many individual craters and strange parallel grooves.
I returned to the sky last night with camera and telescope and took a few additional photos of the star clouds featured in yesterday's blog plus the Venus-Regulus conjunction. The mosquitos were spectacular again and as of 11 a.m. today I was still trying to get them out of my car. My younger daughter, an expert at bug nabbing, helped me nail at least a dozen hangers-on. Thank you Maria!
Venus and Regulus seen through the horizon haze during twilight last night. They'll still be near one another tonight. 35mm lens at f/2.8, ISO 400 and 25-second exposure. All photos credit: Bob King
This and the following two photos are closeups of the three star clouds we talked about yesterday. This one is the brightest and the one that stands out the best -- the Scutum Cloud. It was shot with a 180mm telephoto lens on a tracking mount. Just look at how many stars and dark nebulas you can see!
The Small Sagittarius Star Cloud has two obvious dark spots along its top or northern edge. They're the dark nebulas B93 and B92 (larger, darker one) and were discovered by American astronomer E.E. Barnard. The pink patch at top left is the bright Swan Nebula, also known as M17. If you can find the star cloud, the Swan is very obvious in a pair of binoculars.
The Large Sagittarius Star Cloud is similar in size to the Scutum Cloud but rather low in the sky from my northern location. The glowing puff at top is the Lagoon Nebula, easily visible in binoculars and even with the naked eye from a dark site. The two star clusters at lower right are M7 (bottom) and M6.
I've included this photo of the Andromeda Galaxy to have a little fun. The first two people to identify the object in the blue box and explain why it's relevant to our discussion of Milky Way star clouds will each win a stony meteorite from the Sahara Desert. Please use the Comments link below to send me your answer. Thanks! (the object to the left and Andromeda is one of its companion galaxies.)