This image shows glowing plasma in the Sun's corona, our star's extremely hot upper atmosphere. The plasma, which is like a magnetized gas, flows along curving magnetic field lines. The "coronal loops" in this view indicate that this is an active region on the Sun where powerful magnetic fields might spawn solar flares or coronal mass ejections (CMEs). These loops span a distance roughly equal to 30 times the diameter of Earth. The Transition Region and Coronal Explorer (TRACE) satellite captured this shot on November 6, 1999. The image is not of visible light; instead it is from the Extreme Ultraviolet (EUV) portion of the electromagnetic spectrum at a wavelength of 171 . This part of the UV spectrum lets us see features in the Sun's atmosphere that have temperatures around 1 million Kelvins.
Image courtesy TRACE/NASA.