NASA’s Messenger probe, which is orbiting the planet Mercury, 107 million kilometers away, was in a position to watch the full moon go dark during the Oct. 8 total lunar eclipse.
Mercury and Messenger are currently on the other side of the sun, off to the side from Earth’s perspective. That was a perfect spot for seeing the sunlit moon blink out as it passed into Earth’s shadow.
“From Mercury, the Earth and moon normally appear as if they were two very bright stars,” Hari Nair, a planetary scientist at Johns Hopkins University Applied Physics Laboratory, said in a news release issued Friday. Earth is just five pixels across in the field of view for Messenger’s narrow-angle camera, and the moon is just over one pixel across.
Messenger’s science team produced a time-lapse video from 31 images of Earth and the moon, taken at two-minute intervals. Those pictures span the hour from 5:18 to 6:18 a.m. ET Oct. 8 — a time period during which the full moon’s disk gradually became fully covered by the darkest part of Earth’s shadow. To enhance the eclipse effect, Nair said the images were enlarged to double the apparent size of the Earth-moon system, and the moon’s brightness was increased by a factor of about 25.
This isn’t the first time Messenger has gotten in on an interplanetary phenomenon. A year ago, the Mercury probe snapped a portrait of Earth and the moon at the same time that NASA’s Cassini probe was taking a picture of Earth as seen from Saturn.
Seeing pictures of celestial bodies together, from different far-flung perspectives, helps us realize that we’re all in one big solar system — and that today’s robotic explorers are expanding our view of the planetary neighborhood.