Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

A Radar Image of Planet Earth
Credit: NASA, JPL Imaging Radar Program

Explanation: This image of Mt. Rainier, Washington USA, planet Earth, was produced by the Spaceborne Radar Laboratory which flew on the Space Shuttle Endeavour in 1994. Radar, short for RAdio Detection And Ranging, is a technique which coordinates the operation of a radio transmitter and receiver to measure the direction, strength, and timing of radio echos from the surface of distant objects. An actual image of an object can be constructed by recording and analyzing many echos. One advantage of using radar imaging in planetary studies is that images can be made regardless of cloud cover or lighting conditions. During the early 90s, NASA's Magellan spacecraft was able to use radar imaging to produce similar high resolution maps of the surface of Venus.

For more information about the picture click here.

Tomorrow's picture: A World Explorer

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.