Oct 29 2008
How to judge the height and distance of a shooting star
On a mailing list of the Orange County Astronomers, Donald Lynn told how to estimate the height and distance of a meteor or shooting star:
You can get a rough estimate of the distance, due to a characteristic of meteors. Most begin glowing when they reach 60 miles altitude, and stop glowing when they reach 40 to 45 miles altitude. So the assumption that the beginning of the meteor is 60 miles high (or end about 40), combined with simple geometry, including curvature of the Earth, tells you roughly how far away it is.
For example, a meteor beginning at 60 degrees elevation is about 35 ground miles away, 30 degrees elevation is about 100 miles, 15 degrees elevation is about 200 miles, 5.7 degrees elevation is about 400 miles, on the horizon (0 degrees elevation) is about 700 miles. The end points of meteors, being lower, are substantially closer for the same elevation angles. Objects in the sky lower than 15 degrees are often lost in murky atmosphere, though local exceptionally clear conditions occasionally occur. So it is unusual to see a meteor more than 200 miles away. So observers more than 400 miles apart would rarely see the same meteor, and then only when looking in the azimuth toward the other observers location, and fairly low to the horizon.
An exception to this is the rare meteor that hits the atmosphere at a very shallow angle to the ground, just sort of grazing the atmosphere, so the beginning and end point of glowing would be widely separated, and thus allow a larger region to see it.
