Hot Planet

StarDate: June 3, 2009

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As we head toward summer, the Sun isn't always the most welcome presence. Its heat can feel oppressive, and at times it's downright dangerous. Yet all of that energy comes from a star that's so far away that you can cover it up with the tip of your thumb with room to spare.

So imagine what conditions would be like if we were so close to the Sun that it looked 20 times wider -- so big that you'd need both hands to cover it up.

That's the case for a planet orbiting a star in Ophiuchus, the serpent bearer, which is in the eastern sky this evening. The planet is just five percent as far from the star as we are from the Sun.

The system is known by its catalog number -- HD 149143. The star is a little heavier than the Sun. It's also a few billion years older, so it's nearing the end of its life. That's made its outer layers puff up, so it's a lot bigger than the Sun.

The planet gets a hefty dose of energy from the star. Every square foot receives about 400 times more energy than we receive from the Sun, so temperatures at the top of its atmosphere are probably thousands of degrees.

The planet is probably a big ball of gas that resembles Jupiter, the giant of our own solar system. All that energy from the star should boil off the top layer of its atmosphere. And it probably creates tremendous turbulence, with hot air currents racing around the planet like streams from a fire hose -- streams of air stirred up by a sky-filling star.

Script by Damond Benningfield, Copyright 2009

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