Earth, from Mars

Here’s the latest view of our blue marble from Mars, courtesy of Mars Reconnaissance Orbiter:

pia21260

It’s a composite image, merging images taken through different filters to produce color (although not “true” color, since MRO can see in infrared — vegetation shines very brightly in infrared, which makes Earth redder than it would be to the human eye), and processing Earth and Moon separately so that Moon can be bright enough to see without making the Earth just a big white smear.  The Earth is one of the brightest objects in  the solar system, and while the Moon looks really bright from here, it’s actually much darker than the Earth.

Believe it or not, the Moon was the real target of this image.  MRO isn’t really equipped to take this kind of picture, since it has what’s called a “pushbroom” camera (great for mapping, terrible for portraiture or landscapes), but once every now and again it does — for calibration purposes.  When this image was taken, the Moon was almost directly opposite the Earth from Mars’ perspective.  That means it’s the Earth-facing side of the Moon that we can see — the same side of the Moon we’ve all grown up seeing.  The lunar nearside is the best-known celestial object, and therefore a perfect calibration target.  😉  They know precisely how bright it should be.

Pretty neat, huh?

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