Sun  Planets and Moons  ID: 4525

LRO Images the May 2012 Solar Eclipse

On May 20, 2012, Lunar Reconnaissance Orbiter turned away from the Moon so that its camera (LROC) could point at the Earth. LRO periodically uses the Earth as a target for calibrating the cameras, but in this case, it was imaging the shadow of the Moon during an annular solar eclipse. The LROC narrow-angle camera (NAC) captured four images of the shadow on two successive lunar orbits.

This isn't as easy as pressing the shutter button. Each of the twin NACs comprises a single scanline of 5064 pixels. Ordinarily, the camera is pointed straight down at the Moon, and the orbital motion of the spacecraft sweeps the scanline over the lunar surface to build up an image. (This sweeping business is the reason such single-scanline cameras are often called pushbroom sensors.) To take a photo of the Earth, LRO must be continuously rotated, or slewed, to sweep the scanline across the disk of our home planet. After the first photo in each orbit, LRO's slew was reversed, sweeping the scanline in the opposite direction.

Because the Moon's orbit is elliptical, its distance from Earth and its apparent size in the sky can vary by about 14%. An annular eclipse is a solar eclipse that occurs when the Moon is at the far end of this range and isn't quite big enough to cover the Sun, leaving a ring, or annulus, of sunlight around the edge of the Moon. This is why there's no central black umbra in the LROC images.

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Visualization Credits

Ernie Wright (USRA): Lead Visualizer
Laurence Schuler (ADNET Systems, Inc.): Technical Support
Ian Jones (ADNET Systems, Inc.): Technical Support
Please give credit for this item to:
NASA/GSFC/Arizona State University

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LRO (Lunar Reconnaissance Orbiter)

Data Used:
LRO/LROC/Narrow Angle Camera May 20-21, 2012
Note: While we identify the data sets used in these visualizations, we do not store any further details nor the data sets themselves on our site.

SVS >> Moon
SVS >> Solar Eclipse
SVS >> Sun
GCMD >> Earth Science >> Sun-earth Interactions
SVS >> Hyperwall
SVS >> Eclipse
SVS >> Heliophysics
SVS >> Sun-Earth-Moon Interactions
SVS >> Sun and Earth
NASA Science >> Sun
NASA Science >> Planets and Moons

GCMD keywords can be found on the Internet with the following citation: Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version