Tuesday, May 11, 2010

Texas Star Party & Meteors

I'm spending the week at a remote ranch in southwest Texas for the king of all amateur astronomy events, the Texas Star Party. The sky here is the darkest found within the 48 contiguous states, and 700 amateur astronomers converge on the site every May to find the most elusive deep sky objects possible, compare 'scope equipment, and talk science.

The are some serious amateurs, too. There are plenty of 30- and 36-inch (!) telescopes loaded into huge trailers, and my 10-inch Newtonian that barely fits in my car when disassembled is probably about as small as it gets except for the toy telescopes that they bring along for fun or for the kids. (About 99.5% of attendees are middle aged men and their wives, or occasionally women with their husbands, but always old enough to have enough income to invest in all this fancy equipment. It's expensive to do it right.) All lighting is strictly forbidden after 9pm, except for dim red-lensed flashlights pointed at the ground at all times. The earliest scheduled events all week are after 1pm, allowing the astronomers to go to bed at dawn and still get a full peaceful morning of sleep.

Anyway, I just heard a presentation on meteors that taught me two very cool things that I didn't know before, and it was so exciting I had to share. But first a quick review of the basics:

Meteoroids are grains of sand or dust or, rarely, chunks of rock flying through outer space. When they hit the Earth's atmosphere, they burn up and sometimes survive long enough to hit the ground. When they are visible as streaks of light across the sky, they are called meteors. Once they hit the ground, they are called meteorites.

The composition of meteorites helps scientists understand what's going on in other parts of the universe. For example, one meteorite found on Earth contains black diamonds that formed around 7 billion years ago, several billion years before the formation of our own solar system. This meteorite also contains fossilized bacteria, proving that life of some form has existed extraterrestrially. In fact, a great many meteorites contain both left and right handed amino acids.

Anyway, awesome new fact number 1: The glow that we see when a meteor is burning up in the atmosphere is not actually from the burning grain of sand. We're seeing extremely compressed air just in front of the meteor: the meteor is traveling so fast (20 miles per second or so) that the air in front of it is compressed so much that it heats up and glows. This is a fairly recent discovery actually, and JPL allegedly recommended sticking with the burning story in primary school books because it's easy to understand, and they would straighten people out when they got there =)

Awesome new fact number 2, also very recently explained: You can hear meteors! This doesn't make any sense at first because meteors are many miles away, so any sound waves would take a long time to get to the observer. There's no way you could see and hear it simultaneously. Yet people have reported for quite a while, somewhat incredulously, hearing a sort of "electrosonic" buzzing sound as meteors flash across the sky. Now we know why. The meteor creates very low frequency radio waves, which travel much faster than sound since they aren't slowed down by the atmosphere so much. Nearly the speed of light. Of course, such low frequency waves are not audible, but antennae, in particular wire rimmed glasses (conveniently located right next to your ear) vibrate when these radio waves hit them, which we can hear. So, if you go to a meteor shower and don't wear glasses, buy some cheap reading glasses and knock out the lenses; you might get lucky and hear one.

With that, I will leave you with my favorite object in the entire night sky, visible only at very southern latitudes, which I gleefully stared at for at least twenty minutes last night.

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