Things Far Greater than You or Me

Aurora borealis. Watched a documentary on the northern lights and was awe-struck.

The lights are caused by the collision of charged particles in the Sun's solar wind with atoms in the Earth's upper atmosphere. The collison energizes the gases in the atmosphere, which then converts this extra energy to light.

Apparently the best times to catch these lights are during winter in the northernmost regions - if you're here in the U.S., that would be Alaska, from Sept/Oct to Feb/March.

Another addition to the "to-do" list. Better move this one up higher - braving the cold of wintry Alaska sounds like it takes a little brashness of heart. :)
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Did you know that Nov 17-19 of each year is the best time to view the Leonids? The who, you say? It's an annual meteor shower from the comet Tempel-Tuttle.

Here's what I learned:

A comet is a "small" body in the solar system composed of rock, dust, and ice. They orbit the Sun, and can have a "coma" (atmosphere) or a tail, both of which are effects of the sun on the comet body.

Each time the comet swings by the Sun, the interaction produces small particles that spread out along the entire orbit of the comet. This is called the "meteoroid stream." As we also orbit the Sun, if the Earth's orbit intersects with a comet's orbit, the Earth passes through the meteoroid stream at roughly the same time each year. We Earthlings see the intersection as meteor showers.

Meteor showers appear to "radiate" from one point in the sky. They are named after the constellation that the radiate from - hence, the Leonids radiate from the constellation Leo.

Why do they seem to radiate from one point? Because of our viewing perspective. Think of it this way - if you stand in the middle of a railroad track and follow the rails as far as your eyes can see, the tracks seem to converge to a single vanishing point on the horizon. Which you know is impossible, because the tracks are parallel. Perspective, my friends. So meteor particles travel their orbit at about the same velocity in parallel paths, and from where we stand, they look like they start at the same point in space.

These meteor particles enter our atmosphere at high speeds, creating the streak of light that we see. Most of the particles are very small and burn up long before reaching the earth's surface. The larger pieces that do reach the earth's surface are called meteorites.

Very cool, huh? Astronomy is such a fascinating field...

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