Pi Puppis

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Sometimes astronomical numbers are so immense that they're simply, well, astronomical.

Consider a star known as Pi Puppis. It's classified as a red supergiant. It's more than a dozen times as massive as the Sun, but it's a good bit cooler, so its surface glows orange. The star's already entering the last stages of life, and fairly soon, it may explode as a supernova.

What makes Pi Puppis so impressive, though, is its size. If it took the Sun's place in our own solar system, it would extend almost all the way out to the orbit of Mars. It would swallow Mercury, Venus, and Earth, and bake Mars like a red apple.

Since stars are big balls, not disks, Pi Puppis would extend far above the plane of the solar system, too. It would encompass an enormous volume of space -- a volume about 25 million times greater than the Sun's.

But remember that Pi Puppis is only around a dozen times more massive than the Sun. When you compare the size and mass, you realize that Pi Puppis is just a puffed-up gasbag. Its outer layers are so thin that they're hardly more than a vacuum. With the right kind of shielding, you might be able to fly a spaceship fairly deep into the star and come back out again -- a journey through an astronomical giant.

Pi Puppis is quite low in the south at nightfall, in the constellation Puppis, part of the ship that carried Jason and the Argonauts. Look for it well to the lower left of Sirius, the brightest star in the night sky.

Script by Damond Benningfield, Copyright 2008

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