Friday, November 14, 2008


This week NASA and the European Space Agency discovered, for the first time, three planets orbiting a star other than the Sun using direct light observation. While none of the three planets are considered candidates for extraterrestrial life or human colonization, it's still an exciting breakthrough and an advancement toward mapping and understanding the Universe outside our own Solar System.

Formalhaut is a star visible only in the southern hemisphere. It is 25 light years from Earth (relatively close), and is many times brighter than our Sun. Viewing the planets in its orbit is only possible with an instrument called a coronograph, which blocks out most of a star's light allowing scientists to see the relatively dimly lit bodies in its neighborhood.

You can see Formalhaut without a telescope if you live in the southern hemisphere. It's located in the constellation Piscis Austrinus. It has been called "the lonely star of autumn" because it is the only first magnitude star in its section of space. The Persians considered it one of four "royal stars", and it has been mentioned in the fiction of notable authors H.P. Lovecraft, Isaac Asimov, and Philip K. Dick.

Scientists believe Formalhaut is only 200-300 million years old, quite young for a star. It's burning through its hydrogen fuel at an alarming rate, and will consume it all and burn out after only one billion years, only 10% of the lifespan of our own Sun.
The image above is of the entire Formalhaut System, which appears to be streaked because its section of space is filled with clouds of gas and dust.

Usually scientists identify planets as they pass in front of their host star, causing its light to flicker by eclipsing them slightly. This is done using radio telescopes, collecting a type of light the human eye can't see. In the case of Formalhaut, however, we can see the planets directly using visible light.

Most interesting is the not very originally named planet Formalhaut-B. It is at least three times the size of Jupiter, and orbits its host star from 17 billion kilometers away, ten times Saturn's distance from the Sun. It also appears to have a dark system of rings.

NASA and ESA scientists have watched Formalhaut-B for months, verifying that it really is a planet moving in an orbit, and not just a random piece of space rock that happens to be near the star while we're observing it. They are now attempting to find the presence of water vapor in the planet's atmosphere. Since the Formalhaut system is quite young compared to our own Solar System, it can teach us about the conditions under which stars and planets are formed.

This exciting work is possible because of the Hubble Space Telescope, launched into Earth's orbit in April, 1990. You can see images and even video of Formalhaut, its planets, and other parts of outer space for free at the Hubble Space Telescope website.

For my previous posts on outer space, click here.

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