Sunspot Breaks Through (January 16, 2009)

Hi-res TIF image (1.6M)

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STEREO was watching when a sunspot quickly emerged up from below and poked through the surface of the Sun, establishing itself as a nice active region (Jan. 8 - 11, 2009). This spot had the magnetic orientation of a new solar cycle sunspot. As seen by STEREO (Behind) in extreme UV light, the spot displayed many magnetic loops and a good bit of flashing, frenetic activity as it rotated around with the sun. As of this writing (January 14, 2009) it seems to be somewhat diminished but still active. Active regions are areas of intense magnetic activity that are often the source of solar storms. Analysis of the area and review of the coronagraph images from the other STEREO spacecraft (Ahead) suggest that the region triggered a small coronal mass ejection (CME) just about at the time that it emerged. This CME material reached the Behind spacecraft on Jan. 14, where it was detected by the onboard IMPACT magnetometer.

Currently, the two STEREO spacecraft are separated by almost 90 degrees from each other along Earth's orbit. This is a particularly good time for CME observations because material ejected in the direction of one spacecraft is observed from the side by the other spacecraft. That same material is then later detected by the solar wind instruments as the CME streams past the spacecraft. Thus, by combining data from the two spacecraft, STEREO is able to merge particle and imaging measurements for the same event.

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.