This picture may look like a delicate ocean coral ... or a microscopic view of a stained tissue sample ... or a visualization of someone's psychedelic dream. But it's actually an image of Russia's Lena River delta, captured in the year 2000 by the Landsat 7 satellite. The colors don't reflect what you would actually see if you were looking down from Landsat's 438-mile-high orbit; rather, they represent different types of surface composition, ranging from vegetation-covered terrain to bare ground and bodies of water. This online tutorial explains the seemingly crazy color scheme.

The Lena River is about 2,800 miles (4,400 kilometers) long, making it one of the largest rivers in the world. The Lena Delta Reserve is the most extensive protected wilderness area in Russia, providing an important refuge and breeding grounds for many species of Siberian wildlife.

This picture of the Lena Delta is the fifth treat in our Cosmic Log Space Advent Calendar. Every day from now until Christmas, a fresh image of Earth as seen from space will be posted to Cosmic Log and Photoblog. But you don't have to wait until tomorrow to sample some more Landsat goodness: Go ahead and feast your eyes on this year's "Earth as Art" slideshow.

Here are more space images, from our own Advent calendar as well as others on the Web:

• From Day 1: The Cosmic Log Advent Calendar so far
• Door 2 for Dec. 2: 'Alien' lake seen from space
• Door 3 for Dec. 3: Egypt's river of light
• Door 4 for Dec. 4: Tallest building reaches for the sky
• The Big Picture at Boston.com: Hubble Advent calendar
• Planetary Society: Solar system Advent calendar
• Zooniverse Advent calendar