A rather unusual, long, and clearly defined magnetic loop caught our eye this week. This extreme ultraviolet image (EIT 171 Angstrom) taken 6 Sept. 2004 captured a lanky loop that is linking two active regions far from each other via their magnetic field lines. It appears to extend to an active region on the far side of the Sun that has not yet rotated into view. Its length is estimated to be around 300,000 miles (500,000 kilometers). The video shows in sequential frames taken six hours apart that the loop is first visible at 19:00 on Sept. 5 and disappears 24 hours later. The loop is barely perceptible in any of the other three extreme ultraviolet wavelengths imaged by SOHO.

In a low-density but highly ionized gas (or "plasma") such as the Sun's outer atmosphere, the magnetic field rules: charged particles must spiral around closely aligned, loop-like magnetic fields. The closed magnetic loops originate in bright "active regions" of strong magnetic field. These images were obtained in the light from eight and nine times ionized, gaseous iron, at temperatures around a million degrees Kelvin.

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.