These great pictures are from the SOlar and Heliospheric Observatory website. This ultraviolet image of the Sun shows a very long filament slanting up roughly at a 45 degree angle across much of the Sun, underneath a long and narrow coronal hole (22 Feb. 2005). Filaments are twisting masses of cooler ("only" 10,000 - 100,000 degrees Kelvin) gas contained by magnetic fields above the Sun's surface in the midst of the much hotter (~ 1,500,000 K) corona. Filaments are called prominences if observed on the Sun's limb or edge.

Ultraviolet Image

H-Alpha Image (Courtesy: SOHO, Click images for Hi-Res)This particular filament was already there 28 days ago (one solar rotation earlier), as were the two coronal holes. While filaments are fairly common, this one is longer than most that have ever been seen. The filament is particularly well visible in this H-alpha image obtained at the Kanzelhoehe Solar Observatory.
This video shows the filament virtually unchanged for two days. One (looking closely) can detect (around 10:00 UT on Feb. 22) a small coronal mass ejection as it blasts out into space from the lighter, upper active region on the right edge of the Sun.