Astronomy Picture of the Day

Explanation: About 1,300 images from the Lunar Reconnaissance Orbiterspacecraft's wide angle camera were used to compose thisspectacular view of a familiar face -the lunar nearside.But why is there a lunar nearside?The Moon rotates on its axis andorbits the Earthat the same rate, about once every 28 days.Tidally lockedin this configuration, thesynchronous rotationalways keeps one side, the nearside,facing Earth.As a result, featured in remarkable detail in thefull resolution mosaic,the smooth, dark,lunar maria (actually lava-flooded impact basins),and rugged highlands, are well-knownto earthbound skygazers.To find your favorite mare or large crater, justfollow this linkor slide your cursor over the picture.The LRO images used to construct the mosaic were recorded overa two week period in December 2010.