This is CBSI In The World. I'm John Bachelors. Hot Jupiter, Astronomies. I welcome Ken

Croswell, the author of The Alchemy of the Heavens, the Lives of Stars and Planet Quest,

to introduce us to a new theory about hot Jupiter's, and how they got so close to their

sons that they're orbiting, I mean within days around a sun.

Ken, very good evening to you. What is a hot Jupiter? What is it to find? Good evening to you.

Good evening, John. Hot Jupiter's were an absolute shock to astronomers when they

were first discovered back in 1995. Very first one was sound going around the star that's

almost identical to the sun, called 51 Pegasy. That star's 51 light years from Earth. And

it's very similar and luminosity and temperature to our own star. Now to understand how shocking

hot Jupiter's are, let me sketch out the layout of our solar system first. We have the planets

closest to the sun, we're up to Revenus Earth and Mars, they're all small planets made

of rock and iron. And then at much larger distances from the sun, we have the giant planets,

two gas giants, Jupiter and Saturn, and then two ice giants, Revenus and Neptune. And then

beyond that, we have smaller worlds made of rock and ice, Pluto and Iris. And we naimely

thought, prior to 1995, that other solar systems going around some like stars would resemble

ours. All planets close to the star, giant planets far from the star. And then in 1995,

two astronomers in Switzerland, Michelle Mayor and Divi-A-K-Low, discovered this very strange

planet going around the star 51 Pegasy. It had about 60% of the mass of Jupiter, so it was a

gas giant. But it was much closer to its sun than Mercury. The intermost planet is to

be the Arsa. And in fact, it's so close to the sun that it goes around every 4.2 days.

And so it's a very hot planet and yet it's a giant planet. It's not at all like the planet

Mercury. Mercury is a small planet. Here we have a giant planet going around its star.

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