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©University Calgary |
Close-up of Tagish Lake fragile carbon porousity. |
Comets
"A completely unexpected surprise is that the chemistry of Enceladus, what's coming out from inside, resembles that of a comet," says Hunter Waite of the Southwest Research Institute, principal investigator for the Cassini Ion and Neutral Mass Spectrometer. "To have primordial material coming out from inside a Saturn moon raises many questions on the formation of the Saturn system."
On 12 March, Cassini flew through the huge plume of steam and other gases that spews from fissures at the moon's south pole. A glitch prevented the spacecraft's dust analyser from studying the makeup of the plume, but another instrument, called the Ion and Neutral Mass Spectrometer (INMS), did sample its chemistry.
As well as water vapour, the INMS detected carbon dioxide, methane and a range of more complex organic chemicals such as propane.
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©NASA/JPL/GSFC/SwRI/SSI |
Heat radiates from the entire length of 150-kilometre-long fractures on the south pole of Saturn's icy moon Enceladus |
This week's offering comes from Arthur C. Clarke, the science fiction novelist, who died on Wednesday. In 1994, he urged Op-Ed readers to look to the skies--or risk going the way of the dinosaurs.
In a paper submitted to the Astrophysical Journal Letters, a trio of Hungarian and Australian astronomers describe capturing the most distant cometary activity ever seen.
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©Dennis di Cicco |
Comet Hale-Bopp amid its glory on March 17, 1997. The comet still shines in the outer solar system, but at a mere 20th magnitude. |
Why do some of the closest bright stars to the solar system lie in front of the bright stars of the winter Milky Way? This foreground and background have nothing to do with each other, but they combine to make our winter evening sky especially starry-bright.
Why, from Earth's viewpoint, do planets shine just about as bright as the brightest stars?
Why are the apparent sizes of the Moon and Sun so nearly alike? They're just right to give us the most spectacular-looking (if rather rare) total solar eclipses.

The largest crater in the Chiemgau field in Bavaria is water-filled Tuttensee, located near the village of Marwang. At the water surface, Tüttensee measures 1,200 feet across. but the original crater may have been twice as large. Photo credit: Chiemgau Impact Research Team.