#dscovr

A spacecraft's camera snapped this view of the (normally) dark side of the Moon crossing the face of the Full Earth. 

Study of Earth & Moon as seen by the EPIC camera on the DSCOVR spacecraft.

The Real Dark Side of the Moon

NASA’s Deep Space Climate Observatory (DSCOVR) has captured a view of the moon that is impossible to see from Earth—the “dark side,” illuminated as it passes between our planet and the Sun. The images were made by DSCOVR’s four megapixel Earth Polychromatic Imaging Camera (EPIC), from the satellite’s position a million miles away from the Earth on July 16.

Iceglint from space

Mysterious rainbow flashes were appearing in images taken by the EPIC camera aboard NASA's Deep Space Climate Observatory (see http://bit.ly/2rvkIhi and http://bit.ly/2rdkXwR for our previous coverage of this satellite), sitting some 1.6 million km sunwards from our planet. When hundreds of these flashes had accumulated over both land and sea (it's easier to invoke varied kinds of reflection effect over water since some of them look like mirror flashes) the public (who have access to DSCOVR's images on the mission website) began to write in asking for an answer.

It turned out that they had been spotted before in 1993 when Carl Sagan was looking at shots of our planet taken to calibrate the cameras aboard the Galileo satellite as it swung by to get a gravity assist or two from Earth on its long cold journey towards Jupiter. Indeed these older images also show flashes over land, showing that some other mechanism than simple reflection from water bodies was creating them.

That leaves some sort of atmospheric phenomenon, and after some experimentation a team confirmed the source as ice crystals high up in the air column reflecting the incoming solar rays. They confirmed 866 events in 14 months of operation, which show up in 3 colours since an image is taken in 3 stages through different colour filters. They proved it by modelling the angles between Earth, Sun and spaceship, showing that the flashes (which only manifest in certain latitude bands) only appeared in the pictures when the geometrical configuration between the three objects was right with the ice crystals floating near horizontal in the air, which also eliminated lightning and other optical phenomena or instrumental glitches as alternative possible sources. The data also pinpointed the altitude of the events as 5-8km, so wispy cirrus clouds are probably to blame.

This data is important for refining the accuracy of the world's climate and atmospheric models, and help refine our knowledge of the relationship between clouds and the air column. It might also help in the analysis of exoplanetary atmospheres, a science now in its infancy but developing fast as instrumentation and telescopes progress. The signals from Earth were strong enough to overwhelm the instrument, so maybe such glints on other planets will enrich our search for our own blue globe's twin.

Loz

Image credit: NOAA/NASA

Two NASA spacecraft capture annular eclipse from space.

NASA’s Deep Space Climate Observatory captured the moon’s shadow crossing the Earth February 26. The rare annular solar eclipse was visible in much of the southern hemisphere. An annular eclipse occurs when the moon is farther away from the Earth than in a normal eclipse and does not completely block out the sun during totality. DSCOVR also captured a total solar eclipse on March 8, 2016. The satellite has a unique vantage point on the Earth-Moon system from its orbit at the L1 LaGrange point one million miles away from Earth. NASA’s Terra satellite also captured the eclipse. The climate monitoring satellite saw the moon's shadow in its field of view over southern South America, as seen by the brownish tint to the clouds in the image below. The black area on the left half of the image represents the area outside the spacecraft’s field of view.