Thursday 24 December 2015

Star Colors and Pinyon Pine

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Beautiful, luminous decorations on this pinyon pine tree are actually bright stars in the constellation Scorpius and the faint glow of the central Milky Way. Captured in June from the north rim of the Grand Canyon of planet Earth, the shallow, close focus image has rendered pine needles on the tree branch sharp, but blurred the distant stars, their light smeared into remarkably colorful disks. Of course, temperature determines the color of a star. Most of the out-of-focus bright stars of Scorpius show a predominately blue hue, their surface temperatures much hotter than the Sun's. Cooler and larger than the Sun, and noticably redder on the scene, is giant star Antares at the heart of the scorpion. In focused, telescopic views the whitish disk at the upper right would be immediately recognizable though, reflecting the Sun's light as ringed gas giant Saturn.

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Gullies on Mars sculpted by dry ice rather than liquid water

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Mars's gullies may be formed by dry ice processes rather than flowing liquid water, as previously thought. Scientists show that, during late winter and spring, underneath the seasonal CO2 ice layer heated by the sun, intense gas fluxes can destabilize the regolith material and induce gas-lubricated debris flows which look like water-sculpted gullies on Earth. Since 2000, the cameras in orbit around Mars have transmitted numerous images of small valleys cut into slopes, similar in shape to gullies formed by flowing water on Earth. The gullies seem less than a few million years old-and sometimes less than a few years old.
via Science Daily
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