Opportunity takes a rest stop at a crater

In its 14 mile multi-year trek to Endeavour Crater — now about half completed — the Mars rover Opportunity has stopped to take a short rest stop at a small crater.

The crater, dubbed “Santa Maria Crater” by the scientists who operater Opportunity, is about the size of a football field. What makes it especially interesting are the sharp rocks piled up on its rim, as they are probably debris ejected from the crater at impact. Since this material probably came from deep below the Martian surface, it is also likely to hold information about the Martian geological past, thereby making it a prime research site.

Santa Maria crater

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The sun found to vary in unexpected ways

Recent monitoring of the Sun’s brightness as it went from maximum to minimum in its solar cycle has found that, surprisingly, the changes in brightness across different wavelengths do not necessarily vary in lockstep. Key quote:

SIM suggests that ultraviolet irradiance fell far more than expected between 2004 and 2007 — by ten times as much as the total irradiance did — while irradiance in certain visible and infrared wavelengths surprisingly increased, even as solar activity wound down overall. The steep decrease in the ultraviolet, coupled with the increase in the visible and infrared, does even out to about the same total irradiance change as measured by the TIM during that period, according to the SIM measurements.

The stratosphere absorbs most of the shorter wavelengths of ultraviolet light, but some of the longest ultraviolet rays (UV-A), as well as much of the visible and infrared portions of the spectrum, directly heat Earth’s lower atmosphere and can have a significant impact on the climate. [emphasis mine]

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