If you noticed a fairly bright object passing steadily from left to right in the coronagraph images from SOHO this week, you might want to know what it is. It's Saturn. It was first visible in our C3 (broader field of view) coronagraph on July 28, 2006. It entered the field of view of our C2 instrument (see picture and video above) on Aug. 5. Saturn of course is nowhere near the Sun. It revolves around the Sun once every 29 years or so at a distance of 1.4 billion km from the Sun on its far side from us here at Earth. It appears to move fairly quickly in the video clip (which covers 3.5 days of the passage) because the rather narrow view from SOHO is moving around the Sun at about the same speed as Earth. The spreading of light to each side is an optical aberration. It is caused by the relatively bright light reflected from Saturn that overwhelms our coronagraph's sensitive detectors -- we do not see enough detail of Saturn to be able to distinguish its ring system. The last time SOHO observed Saturn was about a year ago, and before that was late July, 2004, and before that early July in 2003, i.e., whenever that area of the sky where Saturn continues its slow trip around the Sun enters into our field of view.

Previous Picks of the Week

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.