Hubble Takes First Image of an Extrasolar Planet

An artist's concept of Fomalhaut b

The image on the left is the first visible-light photograph of a planet orbiting another star, an extrasolar planet. It was taken by the Hubble Space Telescope. The planet, named Fomalhaut b, orbits the star Fomalhaut. Fomalhaut b is about three times the mass of Jupiter, is located 25 light-years away, and is estimated to be 100 million years old.

The first evidence for the planet came in 2004, when an earlier image by the Hubble Space Telescope of Fomalhaut revealed a ring of protoplanetary debris, having a defined inner edge, very similar to the Kuiper Belt around the solar system. In 2005, a team at the University of California at Berkeley proposed that this ring of debris was being affected gravitationally by a planet in between the star and inner edge of the ring.

The Hubble Space Telescope has now photographed a point of light believed to be the planet Fomalhaut b in that debris. The point lies 1.8 billion miles inside the inner edge of the ring.

Even though the object photographed is a billion times fainter than the star Fomalhaut, it is still brighter than what is expected from a planet three times the size of Jupiter. A possible explanation for this is that the planet has a ring of ice and dust orbiting it reflecting light, like Saturn does, which may later coalesce to form moons.

By comparing images from 2004 and 2006, the team was able to calculate the orbital period of the object. Using Kepler's laws of planetary motion, this came out to an 872-year-long orbit.

Further observations of the planet will reveal more information about the planet, such as a more accurate mass.

For more information, visit:

• The HubbleSite News Release
  

Images: NASA