Earth as seen from the Moon during the total eclipse on August 21, 2017. The shadow of the Moon is
centered over Hopkinsville, Kentucky (18:25:30.386 UTC or 1:25:30 pm Central Daylight Time in
Kentucky) Credit: NASA/GSFC/Arizona State University).

NASA’s Lunar Reconnaissance Orbiter (LRO) used its LROC imaging system to look back at Earth and snag imagery during the Great American Solar Eclipse on August 21.

As LRO crossed the lunar south pole heading north at 3,579 miles per hour (1600 meters per second, the shadow of the Moon was racing across the United States at 1,500 miles per hour (670 meters per second).

A few minutes later, LRO began a slow 180° turn to look back at the Earth and capture an image of the eclipse very near the spot of maximum length of totality.

Credits: NASA/GSFC/Arizona State University).

The Lunar Reconnaissance Orbiter Camera’s (LROC) Narrow Angle Camera began scanning the Earth at 18:25:30 UTC and completed the image 18 seconds later (UTC is 4 hours ahead of Eastern Daylight Time, or 7 hours ahead of Pacific Daylight Time).

Typical day on Moon

“While all of Monday’s thrill was in experiencing the shadow of the Moon sweep across us on Earth, on the Moon this was just another typical day,” said Mark Robinson of Arizona State University, and principal investigator of the Lunar Reconnaissance Orbiter Camera.

“The lunar nearside was one week into its two-week night, while the Sun shone on the farside in the middle of its two-week day. For the Moon, and the LRO spacecraft observing the Moon, the real excitement is during a lunar eclipse when the shadow of the Earth sweeps across the Moon.”

Lunar Reconnaissance Orbiter (LRO).


Temperature drop

Robinson added that during the eclipse, the lunar surface temperatures drop rapidly and LRO’s thermal imager, the Diviner Lunar Radiometer, can learn about the material properties of the lunar rocks and soils by studying their temperature just after the lights abruptly go out.

“Though for the LRO spacecraft itself, the Earth’s shadow means that most of the other instruments must be powered down because of the lack of power coming from the solar panels,” Robinson pointed out.

Launched on June 18, 2009, LRO has collected a treasure trove of data about the Moon with its seven powerful instruments. LRO is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Science Mission Directorate at NASA Headquarters in Washington, D.C.

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