Then and Now (February 9, 2007)

On 2007 February 8, the SOHO Extreme ultraviolet Imaging Telescope (EIT) became the first spaceborne solar imager to observe a complete solar cycle. EIT has now been observing for the mean length of a solar cycle, 11.1 years, since its first image was obtained on 1996 January 2. SOHO is the first solar observatory in space to observe a complete solar cycle. It has the unique opportunity of offering a retrospective reaching back over an entire solar cycle. So we can select and compare images and movies of the Sun almost exactly 10 years apart. We took a snapshot of the several weeks (January 15 - February 5, 2007) and pulled together frames from ten years ago (January 15 - February. 13, 1997).

The Sun is fairly close to solar minimum (its lowest level of solar activity) for both of these periods, so one would expect both sequences to show a similar level of activity. In fact, it does. We see very few active regions and no major solar storms. It would appear that the 1997 frames are a little crisper with a bit more sharpness. Well, 11 years of staring at the Sun has probably taken a toll on the CCD imager. Still, what is most remarkable is that a single spacecraft has held up so well and produced such a long and valuable observation record, a record that scientists around the world are studying and analyzing every day.

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.