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Forgive astronomer Geoff Marcy if he was not exactly floored by the recently announced discovery of the largest new object detected in our solar system since 1930: a mini-planet beyond Pluto.
Marcy and his team have turned the science world upside down since 1995 by discovering more than 50 full fledged planets orbiting other stars in the Milky Way galaxy. This is no mere headline-grabbing trick: By measuring the way other stars wobble due to the tug of nearby planets, Marcy and his team have given the science world a new map.
As of now, they can only identify huge planets -- gas giants like Jupiter or Saturn. But soon, science will be able to spot Earth-like planets out there. Thanks to Marcy, astronomers will know where to look and will take a huge step toward better understanding the origins of Earth and mankind.
"To take a picture of another Earth orbiting another star would be the crowning achievement of astronomy if not of science," said Marcy, of the University of California at Berkeley. "I could imagine the day within our lifetimes when we open our newspaper and there on the front page, above the fold, we see a yellow star and next to it a pale blue dot, which would be a planet."
That shouldn't sound far-fetched. There are major technological hurdles to overcome, but then, that's half what makes this so fun for scientists. Space-based telescopes that can block out the image of far-off stars might be launched, just as early astronomers blocked the image of our sun so they could study its atmosphere.
"The idea is we would be able to detect Earth-like planets now with the Hubble Telescope, but the planets get swamped by the glare of the host star," Marcy said. "So how do you overcome the glare?"
Like most serious scientific endeavors, it takes a lot of work. That means painstakingly observing far-off stars for the wobble effect of one or more large planets exerting gravitational influence. The way to do that is to look at stars coming toward Earth, or moving away, so that variations can be detected in the Doppler shift -- toward the blue end of the spectrum, or toward the red. (It's a lot like listening to the whistle of an onrushing train, which is higher-pitched than that of a train traveling away from the listener.)
Nearly 100 planets have been identified, including the biggest discovery of all: a planet somewhat the size of Jupiter that is orbiting 55 Cancri (in the constellation Cancer) at about the same distance as Jupiter.
Having a gas giant orbiting relatively far from its star means that the system most likely has a smaller, rockier planet -- one resembling Earth -- in the crucial zone where it is not too far from its star, and not too close, so that it has liquid water, rather than ice or steam. "Liquid water is the key to life," Marcy said."
The technical details might be numbing, but the basic reality is not: Marcy has given a much more vivid sense of just what is out there in the galaxy, and not just in a theoretical way, but in terms of practical observation.
"It's a huge explosion, a whole new field of science, really," he said. "It engrosses an entire set of academic disciplines, so it's been fun. I even get fairly frequent communications from the religious community. They are interested in knowing how close we are to finding intelligent life in the Milky Way galaxy."
So, about Quaoar, the newly discovered mini-planet, a little perspective might be in order.
"Mike Brown and his collaborators have found a comet that is half the size of Pluto," Marcy said. "We are going to find other comets out there. Clearly, we're going to find some that are bigger than Pluto. The truth is, to be fair, you might say the following: Pluto is an intermediary between a comet and a planet. It's the king of the comets, or it's the puniest of the planets. You might as well call it both."
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