Greetings Earthlings! This is your planet and its moon as seen from Mars, some 127 million miles away.
This composite image, which was released by NASA on Friday, was created using a special camera aboard the agency’s Mars Reconnaissance Orbiter, which is a spacecraft orbiting about 180 miles above the red planet. The camera is called the High Resolution Imaging Science Experiment. It provides scientists with detailed views of the Martian surface so they can better study geological features like its volcanoes and gullies, as well as scope out potential landing sites for future missions.
“It’s the biggest telescope ever sent to another planet,” said Alfred McEwen a planetary geologist at the University of Arizona and the principal investigator of HiRise. Dr. McEwen said that the image was taken while NASA researchers were trying to calibrate the camera. NASA knows precisely what color the moon’s near side is, so when it wants to calibrate HiRise, it points it at the moon and takes some images. NASA then analyzes the pictures and if the colors appear off it can correct the calibration.
“The moon is boring. It doesn’t change, it’s relatively bland and it doesn’t have all of these variations or changing clouds. It’s a good calibration target,” Dr. McEwen said. “The Earth is a bad calibration target with all its variability like clouds and such, but it makes a pretty picture.”
The Earth and the moon appear close in this image, but that is because the moon is actually just behind the Earth. The researchers had to wait until the two celestial bodies were positioned like this because it provided them with the best view of the moon to perform their calibration, Dr. McEwen said.
To make this picture, scientists combined two separate exposures taken on Nov. 20, 2016, which were processed differently. Dr. McEwen said that NASA needed two exposures to make this image because a good image of the moon saturates the Earth, and a good image of the Earth makes the moon appear too dark.
Vegetation appears red in this image, according to Dr. McEwen. The red spot in the middle of the Earth is Australia, the one on the top left is Southeast Asia and Antarctica is the bright white blob in the bottom left.