File:NASA-ExocometsAroundBetaPictoris-ArtistView.jpg

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http://imagine.gsfc.nasa.gov/docs/features/bios/roberge/roberge_image.html

Aki likes this image because it shows the dynamic nature of the planet-formation process, with many processes operating at once.

This is an artist's conception of the view toward the young star Beta Pictoris from the outer edge of its disk. Beta Pictoris is a 12 million year old star located only 19 parsecs from the Sun. It is surrounded by a disk of dust and gas produced by collisions between, and evaporation of, asteroids and comets. A giant planet may have already formed, and terrestrial (Earth-like) planets may be forming.

A young terrestrial planet gaining mass by collision with an asteroid is shown just to the right of center. The planet is dry and without an atmosphere. It will likely acquire one later from the impact of water asteroids, or other kinds of ice-rich asteroids.

A team of astronomers led by Dr. Roberge used NASA's FUSE telescope to learn that the gas in the Beta Pictoris disk is extremely carbon-rich, much more so than expected, based on what is known about asteroids and comets in our Solar System.

The inset panels show two possible outcomes for mature terrestrial planets around Beta Pic. The top one is a water-rich planet similar to the Earth; the bottom one is a carbon-rich planet, with a smoggy, methane-rich atmosphere similar to that of Titan, a moon of Saturn.

NASA press release: http://www.nasa.gov/vision/universe/starsgalaxies/betapic.html