The Moon and Earth imaged from Mars. Credit: NASA/JPL-Caltech/University of Arizona
Here’s a view of our home planet and its lovely Moon captured from 127 million miles away by NASA’s Mars Reconnaissance Orbiter on November 20, 2016. The sunlit part of Earth shows eastern Asia, the Indian Ocean, and Australia with ice-covered Antarctica visible as a bright white spot. The Moon has been brightened in this image, since it would be too dark in relation to a properly-exposed Earth to be readily visible (and I added more dark background to frame them a bit better.) But the positions and sizes of the two worlds are as captured by the HiRISE instrument, which was designed to map the surface of Mars in exquisite detail but occasionally is aimed to take a look back homeward.
Researchers use these images to help calibrate the HiRISE camera, since we know the precise reflectance of light from the Moon in various wavelengths. But it’s also a wonderful chance to see our world from the vicinity of another, which always—at least for me—stirs the imagination.
I can’t help but be reminded of Carl Sagan’s famous 1994 Pale Blue Dot passage:
Look again at that dot. That’s ...