Hitchhiking through space? (February 4, 2005)
Hi-res TIF (4.3M)
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Have you ever heard of a sci-fi book called Hitchhikers Guide to the
Galaxy? It is a humorous book in which a pair of odd characters frolic
though space. Anyway, this unusual image from our LASCO C3 instrument
would certainly make a great cover since the streak looks strikingly
like a highway through space, does it not? Since the launch of SOHO in
December, 1995, we have observed similar images about a dozen times.
(See our Weekly Pick from September 17, 2003). As in each previous case, it appears that some of SOHO's multi-layer thermal insulation (MLI), which has become brittle after over nine years' exposure to solar radiation, has flaked off and is passing in front of the wide-angle view of the coronagraph. The streaking in this 19-second-long exposure is similar to what you would capture if you were to hold a camera lens open for several seconds and take a picture of snow falling. Just as the snowflakes that passed closest to the lens would appear as fat, out of focus streaks, this MLI flake also appear as a thick, bright streak. What caused the MLI to flake off? Probably, a micrometeorite struck the brittle insulation, not an uncommon event for spacecraft. This type of image has sometimes been observed when a cover of one of the instruments has closed with some force and knocked off some of the spacecraft's insulation, but no covers were closing on this occasion. And for those of you who are following the recent images of the LASCO C3 instrument, the bright object that entered the field of view on Feb. 3 from the lower right is Mercury. It will be crossing the field of view until Feb. 24." SOHO began its Weekly Pick some time after sending a weekly image or video clip to the American Museum of Natural History (Rose Center) in New York City. There, the SOHO Weekly Pick is displayed with some annotations on a large plasma display. If your institution would also like to receive the same Weekly Pick from us for display (usually in Photoshop or QuickTime format), please send your inquiry to steele.hill@gsfc.nasa.gov. |
