From a million miles away, NASA camera shows moon crossing face of Earth

August 5, 2015 by Rob Gutro
This image shows the far side of the moon, illuminated by the sun, as it crosses between the DSCOVR spacecraft's Earth Polychromatic Imaging Camera (EPIC) camera and telescope, and the Earth - one million miles away. Credit: Credits: NASA/NOAA

A NASA camera aboard the Deep Space Climate Observatory (DSCOVR) satellite captured a unique view of the moon as it moved in front of the sunlit side of Earth last month. The series of test images shows the fully illuminated "dark side" of the moon that is never visible from Earth.

The were captured by NASA's Earth Polychromatic Imaging Camera (EPIC), a four megapixel CCD camera and telescope on the DSCOVR satellite orbiting 1 million miles from Earth. From its position between the sun and Earth, DSCOVR conducts its primary mission of real-time solar wind monitoring for the National Oceanic and Atmospheric Administration (NOAA).

EPIC maintains a constant view of the fully illuminated Earth as it rotates, providing scientific observations of ozone, vegetation, cloud height and aerosols in the atmosphere. Once EPIC begins regular observations next month, the camera will provide a series of Earth images allowing study of daily variations over the entire globe. About twice a year the camera will capture the moon and Earth together as the orbit of DSCOVR crosses the orbital plane of the moon.

These images were taken between 3:50 p.m. and 8:45 p.m. EDT on July 16, showing the moon moving over the Pacific Ocean near North America. The North Pole is in the upper left corner of the image, reflecting the orbital tilt of Earth from the vantage point of the spacecraft.

This animation features actual satellite images of the far side of the moon, illuminated by the sun, as it crosses between the DSCOVR spacecraft's Earth Polychromatic Imaging Camera (EPIC) and telescope, and the Earth -- one million miles away. Credit: Credits: NASA/NOAA

The far side of the moon was not seen until 1959 when the Soviet Luna 3 spacecraft returned the first images. Since then, several NASA missions have imaged the lunar far side in great detail. The same side of the moon always faces an earthbound observer because the moon is tidally locked to Earth. That means its orbital period is the same as its rotation around its axis.

In May 2008 NASA's Deep Impact spacecraft captured a similar view of Earth and the moon from a distance of 31 million miles away. The series of images showed the moon passing in front of our home planet when it was only partially illuminated by the sun.

EPIC's "natural color" images of Earth are generated by combining three separate monochrome exposures taken by the camera in quick succession. EPIC takes a series of 10 images using different narrowband spectral filters—from ultraviolet to near infrared—to produce a variety of science products. The red, green and blue channel images are used in these color images.

Combining three images taken about 30 seconds apart as the moon moves produces a slight but noticeable camera artifact on the right side of the moon. Because the moon has moved in relation to the Earth between the time the first (red) and last (green) exposures were made, a thin green offset appears on the right side of the moon when the three exposures are combined. This natural lunar movement also produces a slight red and blue offset on the left side of the moon in these unaltered images.

The lunar far side lacks the large, dark, basaltic plains, or maria, that are so prominent on the Earth-facing side. The largest far side features are Mare Moscoviense in the upper left and Tsiolkovskiy crater in the lower left. A thin sliver of shadowed area of moon is visible on its right side.

"It is surprising how much brighter Earth is than the ," said Adam Szabo, DSCOVR project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Our planet is a truly brilliant object in dark space compared to the lunar surface."

Once EPIC begins regular observations next month, NASA will post daily color images of Earth to a dedicated public website. These images, showing different views of the planet as it rotates through the day, will be available 12 to 36 hours after they are acquired.

DSCOVR is a partnership between NASA, NOAA and the U.S. Air Force with the primary objective of maintaining the nation's real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA.

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4.5 / 5 (4) Aug 05, 2015
Incredible imagery, things so familiar yet so novel in juxtaposition as to seem Photoshopped.

It's also quite surprsing to see the actual relative scales - in the iconic Earthrise photo from Apollo, the Earth doesn't seem much larger from the Moon's surface, than the Moon does from here. This leads to the false assumption that their sizes might be similar, which of course is due to the fact that you can't see the Moon's size while on or close to its surface...
3.7 / 5 (3) Aug 05, 2015
So, if that's the dark side of the moon, then where is the secret military base?
1.3 / 5 (3) Aug 05, 2015
FYI, the "Far Side" of the moon is not always dark! Pink Floyd got it wrong!
4.3 / 5 (6) Aug 05, 2015
FYI, dark in this case means not visible (to us). Pink Floyd got it perfectly.
5 / 5 (4) Aug 06, 2015
"There is no dark side in the moon, really. Matter of fact, it's all dark. The only thing that makes it look light is the sun."_Gerry O'Driscoll (Doorman at Abbey Road studio)_

This quote can be heard on Eclipse the 9th and final track of Dark Side of the Moon.
Steve 200mph Cruiz
4 / 5 (4) Aug 06, 2015
This satellite was hung up for 9 years because the Bush administration didn't want to launch it, even after reviews deemed it a very scientifically important mission.
not rated yet Aug 06, 2015
"It is surprising how much brighter Earth is than the moon,"

Indeed. Earth looks good but Moon looks somewhat dark for a full moon. At least, darker than I should have expected for "natural color" images. Post processing? Nice animation Anyway!
5 / 5 (1) Aug 06, 2015
The doorman? Cool! .. I found they used another one of him, for "The Great Gig in the Sky". The line starts with "And I am not frightened of dying...." just prior to one of most E.P.I.C. (to stay in topic) female singer's performance ever...
5 / 5 (2) Aug 09, 2015
"Indeed. Earth looks good but Moon looks somewhat dark for a full moon. At least, darker than I should have expected for "natural color" images. Post processing? Nice animation Anyway!"

Keep in mind that the images are not from a conventional camera, the instrument is a Spectroradiometer.

5 / 5 (1) Aug 09, 2015
Solon. Thanks for the link. EPIC is not a conventional camera, right. Already read about it before posting: http://www.nesdis...heet.pdf
Plus, the article briefly explains the process in the "EPIC's "natural color" images... " paragraph and the next one.
Still no clue why Earth looks so 'natrutal' and Moon looks somewhat 'dark' there, it is not my screen that for sure. According to Adam Szabo, such difference exist.
Well, maybe it is just the images used for this presentation were post processed in a way that don't match the description, like dropping overall brightness. I can't tell really...
5 / 5 (4) Aug 09, 2015
Here is a NASA fact sheet of the Moon. Look at geometric albedo it represents the percentage of light in the visible spectrum that a given planet, asteroid, comet, etc., reflects in the observer's direction: Moon 0.12 Earth 0.367. The Earth is 3 time more reflective per surface area than the Moon. http://nssdc.gsfc...act.html
5 / 5 (1) Aug 09, 2015
I see, good links there people.
Then seems to be they overstated the "photographic-quality" in their previous post
I almost buy it from the former astronaut's testimony, and by comparing with previous instrument's images (MODIS) http://www.nesdis...age.html
...A bit disapointed, but I'll live... :p
A little post processing should have been nice, for the animation at least. Just like New Horizon's team does with raw images http://pluto.jhua...ndex.php
not rated yet Aug 14, 2015
The moon is supposed to be one quarter the size of earth. And it is lesser than that size in this pic. Then, another thing that I noticed is that the moon being closer to the camera should be, if not the same size, at least slightly smaller than the earth. The farther an object is from the viewer, the smaller it should seem, isn't it? But, that is not seen in this picture. Is something wrong with my perspective or the way it is understood? Or is the moon, even smaller than one quarter the size of the earth?
5 / 5 (1) Aug 15, 2015

A rough estimation of the size ratio from my computer screen with a ruler and my sticky fingers: Earth 19.2cm, Moon 7cm, so on this picture the Earth appears to have a size ratio of 19.2cm/7cm = 2.743 x Moon.

NASA's Moon fact sheet http://nssdc.gsfc...act.html
Earth radius: 6378.1km
Moon radius: 1738.1km
Mean distance between Earth and Moon: 378000km

NASA's DSCOVR facts http://www.nesdis...an15.pdf
Distance from Earth: 1500000km
Distance from Moon: 1500000km – 378000km = 1122000km

Ratios radius/distance from DSCOVR point of view:
Earth 6378.1km/1500000 = 0.004252
Moon 1738.1/1122000 = 0.001549
Comparison of those two ratios 0.004252/0.001549 = 2.743 How about that!

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