NASA’s Lunar Reconnaissance Orbiter captures a uncommon view of Earth from the moon.
NASA’s Lunar Reconnaissance Orbiter (LRO) experiences 12 “earthrises” on daily basis, nevertheless LROC (brief for LRO Digital camera) is nearly at all times busy imaging the lunar floor so solely not often does an alternative come up such that LROC can seize a view of Earth. On February 1, 2014, LRO pitched ahead whereas approaching the moon’s north pole permitting the LROC Extensive Angle Digital camera to seize Earth rising above Rozhdestvenskiy crater (112 miles, or 180 km, in diameter).
The LROC WAC could be very totally different than most digital cameras. Sometimes decision is reported as the quantity pixels in a single picture; a cellphone digital camera at present has greater than 5 million pixels (5 megapixels). A single WAC body has solely 9,856 pixels, nevertheless the WAC builds up a a lot bigger picture by exposing a collection of photographs (or frames) as LRO progresses in its orbit; this kind of imaging is known as “push-frame.” Over a full month as the LRO orbit observe progresses round the moon the WAC builds up a group of photographs that covers the complete globe.
Often LRO factors off into area to accumulate observations of the moon’s exosphere and carry out instrument calibration measurements. Throughout these slews generally Earth (and different planets) cross via the WAC’s subject of view and dramatic photographs equivalent to the one proven listed here are acquired. In the picture above, the moon is a grayscale composite of the first six frames of the WAC commentary (whereas the spacecraft was nonetheless actively slewing), utilizing seen bands 604 nm (nanometers), 643 nm and 689 nm. Earth is a colour composite of later frames, utilizing the 415 nm, 566 nm and 604 nm bands as blue, inexperienced and purple, respectively. These wavelengths have been picked as they match nicely the response of the human eye, so the colours are very near true, that’s what the common individual would possibly see. Additionally, on this picture the relative brightness between Earth and the moon is right. Notice how a lot brighter Earth is relative to the moon.
In the animation, the “venetian blind” banding demonstrates how a WAC picture is constructed up frame-by-frame. The gaps between the frames are as a result of the actual separation of the WAC filters on the CCD. The longest wavelength (689 nm) band is at the backside of the scene, and the shortest (415 nm) is at the high; word how Earth is brighter when it enters the high band as a result of the blue from the ocean. The frames have been acquired at two second intervals, so the whole time to gather the sequence was 5 minutes. The video is about 20 occasions sooner than actuality.
Image: NASA/Goddard/Arizona State College