Friday, November 14, 2008

More Gosh Wow

We knew exoplanets were out there, because of the slight variations in the brightness and orbital velocity of the stars they orbit. And in 2005 astronomers imaged a planet orbiting a brown dwarf star - a very young and hot Jupiter class planet) although it probably didn't form in the same way as the planets in the Solar System. And now, two seperate studies have imaged four exoplanets around two more stars. This is truly amazing stuff - real science fiction headline stuff. The first images were obtained by a team using the Gemini North telescope and W.M. Keck Observatory on Mauna Kea. They blocked out the light of the target star, a massive young star named HR 8799, and were able to image in infra red three planets (the picture shows two of them; all are super-Jupiters) - the first pictures of another planetary system.

And a second team, using the Hubble telescope, have tracked another planet in the dust ring surrounding Fomalhaut (above), a massive star just twenty-five light years from Earth. The planet is about the size of Jupiter, and orbits a long way out, with a period of more than eight hundred years.

Now, none of these planets can support life (or at least life as we know it). HR 8799 is a young star and its planets are young too, just sixty million years old, still glowing with the heat of their formation (which makes them easier to spot). The planet around Fomalhaut is a little older, but still much younger than the Earth and the other planets around the Sun, and because Fomalhaut is a massive star it will burn through its hydrogen in just a billion years. But still.

So far we've tallied about 300 exoplanets. Now we've seen five of them directly. It isn't a stretch to imagine that we'll soon have an image of a planet orbiting in a star in the zone where liquid water - and life - can exist. And then, like Macy Minnot, in The Quiet War, who spends some time with a crew who are observing an Earth-like planet, we may for the first time see a pale blue dot like our own, with clouds and oceans and continents. Such times we live in. Such times.

UPDATE: This is a pretty good article on the search for Earth-like exoplanets.


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