Last month, the moon passed in front of the side of Earth that receives sunlight, and a NASA camera on board the Deep Space Climate Observatory (DSCOVR) satellite captured an exceptional shot of it. A collection of test pictures depicts the moon’s completely lighted “black side,” which is never visible from Earth.
NASA’s Earth Polychromatic Imaging Camera (EPIC), a four-megapixel CCD camera and telescope aboard the DSCOVR satellite orbiting 1 million kilometers from Earth was used to take the pictures.
DSCOVR performs its principal task of real-time solar wind monitoring for the National Oceanic and Atmospheric Administration (NOAA) from its position halfway between the sun and Earth.
In addition to providing scientific studies of ozone, vegetation, cloud height, and aerosols in the atmosphere, EPIC keeps a continuous picture of the completely lighted Earth as it revolves.
Next month, when EPIC starts making regular observations, the camera will deliver a sequence of Earth photos that will enable researchers to examine daily fluctuations throughout the entire planet. The moon and Earth will be captured by the camera as the DSCOVR orbit crosses the moon’s orbital plane around twice a year.
On July 16, between 3:50 and 8:45 p.m. EDT, the moon was photographed travelling over the Pacific Ocean close to North America. The North Pole may be seen in the image’s upper left corner, reflecting the Earth’s tilt from the perspective of the spaceship.
The first photos of the far side of the moon were not received until 1959 by the Soviet Luna 3 mission. Since then, other NASA missions have captured highly detailed images of the far side of the moon.
It is surprising how much brighter Earth is than the moon. Our planet is a truly brilliant object in dark space compared to the lunar surface.
Adam Szabo
Because the moon is tidally locked to Earth, the same side of the moon is always visible to observers on Earth. This indicates that its rotational period and orbital period are the same.
Similar images of Earth and the moon were taken in May 2008 by NASA’s Deep Impact mission from a distance of 31 million miles. The photographs demonstrated the moon crossing in front of Earth when the sun was only partially visible.
Three different monochrome exposures taken by the camera quickly after one another are combined to create EPIC’s “natural color” photos of Earth.
To create a range of scientific deliverables, EPIC shoots a series of 10 photos using various narrowband spectral filters from ultraviolet to near-infrared. These color images employ the red, green, and blue channel images.
A tiny but discernible camera artifact is visible on the right side of the moon when three photographs taken roughly 30 seconds apart are combined. The right side of the moon has a tiny green offset when the three exposures are merged because the moon has moved with respect to the Earth between the first (red) and last (green) exposures. In these unedited photographs, this natural lunar movement also causes a tiny red and blue offset on the left side of the moon.
The huge, black, basaltic plains, or maria, that are so noticeable on the Earth-facing side are absent on the far side of the moon. Mare Moscoviense in the upper left and Tsiolkovskiy crater in the lower left are the two biggest landforms on the far side. On the moon’s right side, a tiny patch of darkness can be seen.
“It is surprising how much brighter Earth is than the moon,” 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.”
Next month, when EPIC starts making regular observations, NASA will upload daily color photographs of Earth to a special website for the general public. These photographs, which depict the planet’s rotation throughout the day from various angles, will be made public 12 to 36 hours after they are taken.
The major goal of DSCOVR, a collaboration between NASA, NOAA, and the U.S. Air Force, is to preserve the country’s real-time solar wind monitoring capabilities, which are essential to the precision and lead time of NOAA’s space weather alerts and forecasts.
