Actually there are several satellites (COROT from France, Kepler from NASA) which will measure the variations brightness of stars. They will be able to look at several stars at once, and will be sensitive enough to detect an earth size planet moving in front of the star. Of course this requires systems where earth size planets appear to move infront of the star. These missions will not be able to directly detect earths (as Darwin and TPF) will, but they will let us know they are there and they will be launching in the 2005 timeframe rather thans 2010 or beyond.
the reason why we can find these systems is the large planets are so close to the star that we can notice the periodic nature of the wobbles the planet induces on the star. it might be possible for us to detect our own solar system but we would need a much larger set of data because Jupiter (the only planet we could even have a hope of detecting) takes much longer to orbit the sun than these planets do their own star. of course, this would take much more patience and so be more difficult
There is rather strong semitment on whether Pluto is a planet or not. At the time of its discovery not much was know about it and so everyone was content with it being a planet. However in recent years we have discover more about it. It is not much bigger than the moon and in all likelyhood is just a icey ball of rock. The reason we still call it a planet is this: Once we learned how small it is the discoverer was getting old. The initial debate over its classification was muted because who wants to tell an 85 year old that the planet he discovered isn't really a planet? Shortly after his death, the debate began in ernest. IMHO, Pluto is just a glorified asteroid.
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Actually there are several satellites (COROT from France, Kepler from NASA) which will measure the variations brightness of stars. They will be able to look at several stars at once, and will be sensitive enough to detect an earth size planet moving in front of the star. Of course this requires systems where earth size planets appear to move infront of the star. These missions will not be able to directly detect earths (as Darwin and TPF) will, but they will let us know they are there and they will be launching in the 2005 timeframe rather thans 2010 or beyond.
the reason why we can find these systems is the large planets are so close to the star that we can notice the periodic nature of the wobbles the planet induces on the star. it might be possible for us to detect our own solar system but we would need a much larger set of data because Jupiter (the only planet we could even have a hope of detecting) takes much longer to orbit the sun than these planets do their own star. of course, this would take much more patience and so be more difficult
There is rather strong semitment on whether Pluto is a planet or not. At the time of its discovery not much was know about it and so everyone was content with it being a planet. However in recent years we have discover more about it. It is not much bigger than the moon and in all likelyhood is just a icey ball of rock. The reason we still call it a planet is this: Once we learned how small it is the discoverer was getting old. The initial debate over its classification was muted because who wants to tell an 85 year old that the planet he discovered isn't really a planet? Shortly after his death, the debate began in ernest. IMHO, Pluto is just a glorified asteroid.