Sun plasma loops. Coloured ultraviolet TRACE spacecraft image of an active region of the Sun's surface showing plasma loops. Seen from the side, these fine plasma loops form Sun prominences. Colours represent temperatures: blue is 360,000 degrees Fahrenheit (F); green is 900,000 degrees F; red is 2,7 million degrees F. White is where all colours combine and plasma loops of all tempe- ratures are present. This heating of the Sun's plasma occurs along groups of magnetic field lines in localized regions. Fifteen Earth's would fit into the larger loops. TRACE (Transition Region and Coronal Explorer) spacecraft image taken on 25 April 1998, soon after TRACE was launched.