This is planetary radio. I'm at Kaplan. We return to our regular format, but we will remember Columbia and her crew explorers all.

Our guest this week is also an explorer.

Dr. Steve Howell heads the Search for Extra Solar Planets Project at the Planetary Science Institute.

That search is surely one of the great scientific success stories of our time.

Later we'll get back together with Bruce Betts for What's Up, including our new trivia contest.

First though, here's Emily with a tale of two sons and some extra solar action of her own. Her own. Hi, I'm Emily Lochuwala with questions and answers.

We were asked, is it possible for planets to form around binary stars?

Science fiction movies set on other worlds. for planets to form around binary stars?

Science fiction movies set on other worlds often show skies with two stars,

indicating that the world is orbiting a binary star system.

These star systems are very common. A survey of stars close to the sun

reveals that half are actually binary star systems. In fact, the second

closest star to Earth, Alpha Centauri, is actually a pair of sun-like stars orbiting each other at an average

distance of 23 astronomical units, roughly the same as the distance between our Sun and the

planet Uranus. But is it really possible for planets to form in such a binary star system?

Stay tuned to planetary radio to find out. Dr. Steve Howell, how many planets do we Earthlings now know about?

If you mean outside our solar system?

You can include R9?

R9 plus, uh, something of order of one hundred candidates

uh... i would say that maybe ten or fifteen of those are absolutely for sure

uh... other objects that we might call planet. The rest of them are likely candidates but

not proven so to speak in the astronomical sense.

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