Tuesday, October 30, 2007

Things that go boom in the night

Last night, I took a couple minutes to go out and look for Comet Holmes, the normally-very-faint comet that you can now see with your plain eye. From a parking lot near my place, I could easily see the comet, despite all of the light pollution. So, if you have clear skies, I bet you can see the comet, too. Some charts to help you locate the comet are here. Around 8pm or so, the constellation Cassiopeia is just a bit north of overhead -- it looks like a "W" in the sky. Then look toward the east. The next grouping of stars toward the Eastern Horizon is the constellation Perseus. To me, Perseus looks like the Greek letter pi. Only now, there is an extra star that is just as bright as the brightest stars in Perseus. As I said, I saw it from a well-lit parking lot last night. So, if you go out trick-or-treating tomorrow night, take a long a star chart and try to find the comet!

People in dark skies, away from city lights, can actually see that the comet is not a point, like the stars, but a little fuzzy. The comet is also fairly yellow, in large part because the light coming from it is reflecting the light of our yellow sun. What we are seeing are the dusty remains of some big eruption from the surface of the comet. The dust is slowly expanding away into space, and the dust cloud is currently larger in size than the planet Jupiter! Of course, there is very little dust there, while the planet Jupiter is far more massive than the planet Earth.

Speaking of things splitting up in space, I saw a commercial on TV last night that had an alien spaceship blowing up the Earth (and, on one of the tiny bits of Earth left, a man sits surprised in his pickup truck, which was durable enough to survive the explosion). That got me wondering -- how much energy would it take to blow up a planet? I didn't feel like doing the calculation (it is straightforward, but I can be lazy), but thanks to the magic of Google, I found the answer. It would take about 2 times ten to the 32nd power Joules, or the entire energy output by our sun in about one million seconds (11 and one-half days). For comparison, one second of the sun's energy output could supply all the world's current energy needs for roughly one million years. In other words, if we took all of the Earth's energy production (at the current rate) for one trillion years, stored it up somehow, and turned it into a laser beam, we could disintegrate the Earth. Thankfully, I don't see that happening any time soon.

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