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Hunting Planets IV

August 29, 2015

Hunting for exoplanets can take some patience. Astronomers at McDonald Observatory, for example, have been hunting for planets around a set of 200 target stars for more than 15 years. Yet the search isn’t over. Michael Endl is the project’s lead scientist:

ENDL: It seems like it should be obvious that, after so many years of observing, we should know which star has a planet or doesn’t. We’re searching now for planets that have orbital periods of a decade or more.

Such a planet is big and heavy, but it’s far away from its star. The planet’s gravitational pull causes a change in the star’s motion toward or away from Earth. But the change is so tiny that it can take years to see it and confirm the planet’s presence.

The scientists are looking for such planets because they can tell us a great deal about how our own solar system compares to others. In many systems, the giant planets have moved closer in, perhaps destroying small planets like Earth and Mars in the process. But astronomers aren’t sure how many systems look like that, and how many resemble our own.

ENDL: From a human, philosophical viewpoint, that’s really what we’re interested in — seeing if our solar system is still something relatively rare and special, to have this collection of small, rocky planets in the interior, and in the habitable zone, and then have the giant planets farther out....We still don’t know whether we are living in a typical planetary system or not.

So the search continues — many years after it began.

Script by Damond Benningfield, Copyright 2015

Today's program was made possible in part by a grant from the National Science Foundation.

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