Sun  ID: 11993

SDO Transit - September 2015

On Sept. 13, 2015, as NASA’s Solar Dynamics Observatory, or SDO, kept up its constant watch on the sun, its view was photobombed not once, but twice. Just as the moon came into SDO’s field of view on a path to cross the sun, Earth entered the picture, blocking SDO’s view completely. When SDO's orbit finally emerged from behind Earth, the moon was just completing its journey across the sun’s face.

Though SDO sees dozens of Earth eclipses and several lunar transits each year, this is the first time ever that the two have coincided.

SDO’s orbit usually gives us unobstructed views of the sun, but Earth’s revolution around the sun means that SDO’s orbit passes behind Earth twice each year, for two to three weeks at a time. During these phases, Earth blocks SDO’s view of the sun for anywhere from a few minutes to over an hour once each day.

Earth’s outline looks fuzzy, while the moon’s is crystal-clear. This is because—while the planet itself completely blocks the sun's light—Earth’s atmosphere is an incomplete barrier, blocking different amounts of light at different altitudes. However, the moon has no atmosphere, so during the transit we can see the crisp edges of the moon's horizon.


Credits

Genna Duberstein (USRA): Lead Producer
William D. Pesnell (NASA/GSFC): Scientist
Sarah Frazier (ADNET): Writer
Please give credit for this item to:
NASA's Goddard Space Flight Center

Short URL to share this page:
http://svs.gsfc.nasa.gov/11993

Mission:
SDO

Goddard TV Tape:
G2015-072 -- SDO Transit - September 2015

Keywords:
SVS >> Earth
SVS >> HDTV
SVS >> Moon
SVS >> Solar Wind
SVS >> Transit
GCMD >> Earth Science >> Sun-earth Interactions >> Solar Activity >> Solar Ultraviolet
SVS >> Space Weather
SVS >> SDO
SVS >> Solar Dynamics Observatory
SVS >> Heliophysics
SVS >> Corona
NASA Science >> Sun

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 8.0.0.0.0