Dark Sun Sizzling
Credit: TRACE Project, Stanford-Lockheed Institute for Space Research, NASA
Explanation: Is this our Sun? Yes. Even on a normal day, our Sun is a sizzling ball of seething hot gas. Unpredictably, regions of strong and tangled magnetic fields arise, causing sunspots and bright active regions. The Sun's surface bubbles as hot hydrogen gas streams along looping magnetic fields. These active regions channel gas along magnetic loops, usually falling back but sometimes escaping into the solar corona or out into space as the solar wind. Pictured above is our Sun in three colours of ultraviolet light. Since only active regions emit significant amounts of energetic ultraviolet light, most of the Sun appears dark. The colourful portions glow spectacularly, pinpointing the Sun's hottest and most violent regions. Although the Sun is constantly changing, the rate of visible light it emits has been relatively stable over the past five billion years, allowing life to emerge on Earth.
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Crescent Rhea Occults Crescent Saturn
Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA
Explanation: Soft hues, partially lit orbs, a thin trace of the ring, and slight shadows highlight this understated view of the majestic surroundings of the giant planet Saturn. Looking nearly back toward the Sun, the robot Cassini spacecraft now orbiting Saturn captured crescent phases of Saturn and its moon Rhea in colour a few months ago. As striking as the above image is, it is but a single frame from a recently released 60-frame silent movie where Rhea can be seen gliding in front of its parent world. Since Cassini was nearly in the plane of Saturn's rings, the normally impressive rings are visible here only as a thin line across the image centre. EU probe Cassini has now passed the official half-way mark of its mission around Saturn, but is well situated to complete another two years investigating this complex and surprising system.
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