Night And Day On An Alien World

The Hidden Universe of the Spitzer Space Telescope (Episode 4): Night And Day On An Alien World.

It's as clear as day and night ... but on an exotic alien world! Astronomers have for the first time measured the temperatures varying across the surface of an exoplanet -- a planet beyond our solar system.

This is the Hidden Universe of the Spitzer Space Telescope, exploring the mysteries of infrared astronomy with your host Dr. Robert Hurt.

Planets orbiting other sun-like stars are notoriously difficult to observe; theyre so distant that no telescope is yet powerful enough to photograph them directly. Their feeble light is blurred into the glare of the stars they orbit.Nonetheless, since 1995 astronomers have discovered over 200 extrasolar planets by observing the effects they have on their parent stars. These include gravitationally-induced wobbles, and even faint dimmings of the starlight when the planets pass in front.

The infrared eye of the Spitzer Space Telescope has already proven to be an exciting tool for learning more about these alien worlds.

In 2005, astronomers Drake Deming and Dave Charbineau announced the first detection of light from two extrasolar planets, seen as they went into eclipse behind their stars.

Now, astronomers Joe Harrington, of the University of Central Florida, and Brad Hanson, of UCLA, have taken this one step further. They have actually measured differences between the day and night sides of such a world.

This remarkable result marks the first time any kind of variation has been seen across the surface of a planet outside our solar system. For now only imaginative artists can provide pictures of what they could look like. But until the day we can take real snapshots, astronomers will continue to find clever ways to explore this growing catalog of alien worlds.

---

The Spitzer Space Telescope is the final mission in NASA'€™s Great Observatories Program - a family of four space-based observatories, each observing the Universe in a different kind of light.

• http://spitzer.caltech.edu/