Thursday, December 13, 2012

Watching for (Geminid) meteors

This year's Geminid meteor shower has been projected to be unusually fine this year, and the peak was/is today/tonight (Dec. 13-14), so it would be a good night to escape urban light pollution for awhile. The Geminids are unusual among recurring showers in that their source is not a comet, but an asteroid, Phaethon. Phaethon is unusual among asteroids in that it has a highly elliptical orbit, traveling further from the sun than Mars (where the greatest bulk of asteroids "live" in a belt between Mars and Jupiter) and also coming much closer to the sun than Mercury. It may even have an icy component to its core, which would explain the amount of debris that surrounds it, as this would tend to melt and break up at perihelion. In any case, it's the tiny bits that spread along the approximate orbit of the asteroid itself, and many of them end up encountering earth's atmosphere, where they burn up quickly but make a very nice display for us if we chance to be looking in the right direction at the right time. Because of the geometry of Earth's orbit and Phaethon's, these "shooting stars" appear to radiate from a point in the constellation Gemini.

I did a quick drive out to Jordan Lake, away from the substantial light pollution of Raleigh, and arrived just before sunset. I found myself at a western exposure, where I could enjoy the dusk over the water, but facing opposite where Gemini would be rising at about 8 pm. I was ready for my first photo op, but had to set up in a hurry!

After the sun disappeared, with the sky still glowing, I looked for ways to narrow the focus to color contrast and graphic design. That meant a telephoto lens (narrow angle of view) and dropping the exposure value to intensify color and turn dark areas into silhouette.

The birds became somewhat active after sundown, but remained at the far side of the lake, both in the air and on the water.

With the sky continuing to darken, but no stars visible yet in the west, a plane added its contrail to the scene.

I included a boat launching ramp in a few foregrounds, opting for variety of texture instead of pristine nature.

Finally the sky became dark enough for thousands of stars to be visible in the east. There was also a constant stream of air traffic, but I got one frame with no airplane lights visible. No meteors either, which is no surprise because Gemini was still well below the horizon, and any horizon grazers would likely have been hidden by the trees in the east.

And then I had to leave! I probably won't put much effort into photographing meteors tonight, but I'm going out for a post-midnight look just to enjoy the experience. Shooting stars do bring good luck - the fine fortune of experiencing something beautiful with such fascinating phenomena behind it!


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