690x500 JPEG, 67kB
(see also: 690x500 GIF, 254kB,
400x280 GIF, 101kB)
Ths image shows the Sun as viewed by the Soft X-Ray Telescope (SXT) onboard the orbiting Yohkoh satellite. The bright, loop-like structures are hot (millions of degrees) plasma (electrically charged gas) confined by magnetic fields rooted in the solar interior. An image of the sun in visible light would show sunspots at the feet of many of these loops. The halo of gas extending well beyond the sun is called the corona. The darker regions at the North and South poles of the Sun are coronal holes, where the magnetic field lines are open to space and allow particles to escape.
As part of the RSD Program, the Yohkoh Public Outreach Project will create animations of the sun using images like this one.