A Barrage of ‘Shooting Stars’

When you see a shooting star, it’s not actually a star. It’s a piece of space debris, usually left behind in the wake of a comet, burning up in our atmosphere. As comets near the sun in their orbits, they melt a little bit, leaving behind tiny pieces of rock. When we pass through these “dust trails,” many of those bits smash into Earth’s atmosphere and burn up. The bright streaks and shooting stars that you see during a meteor shower, as majestic as they may appear, are simply the result of minuscule pieces of sand vaporizing in our atmosphere. The most impressive-looking of these meteors have “tails” of their own, which occur due to the heat of the meteor ionizing the gas around it. The meteors themselves are just tiny grains, but their deaths are far more spectacular.

A long-exposure photograph of the Leonid meteor shower from Wikipedia Commons.

During a meteor shower, all of the meteors will appear to be coming from a single “radiant point.” Because the dust trail of a comet continues moving in the direction of the comet (inertia), it’s all moving in the same direction when the Earth moves through it – so, while the meteors aren’t, in fact, coming from a single point, they all appear to be pointing away from that radiant point. Any meteors that don’t point back to the radiant point are just from random space dust instead of a comet’s dust trail.

Every year, around August 11th-13th, we pass through the dust trail of Comet Swift-Tuttle, causing the Perseid meteor shower. It’s called Perseid because the radiant point of the shower is in the constellation Perseus, in the Northeastern summer sky. I woke up my family last night and we went out to watch it, but the shower usually goes on for three full nights, peaking just before dawn each night, so there’s still plenty of time to go out and see as many as 70 meteors an hour, which is awesome, in the old sense of the word.

A few tips for watching meteor showers:

  • You don’t need a telescope or binoculars or any special equipment, just your eyes.
  • Go out after the moon has set, so the sky is dark. This often means waking up very early in the morning. It’s worth it. (North of the equator, you may be able to see meteors right when it gets dark. South of the equator, wait until after midnight, when the radiant is above the horizon.)
  • Go to the darkest place possible, preferably far away from any cities – the beach is perfect for this. Also, since the meteors appear all over the sky, an open area is ideal – again, the beach or an empty field is great.Β Even in the city, though, you’ll likely be able to see some meteors if you watch for them.
  • Bundle up and bring a thermos of something – it’s always colder than you think it’s going to be.
  • Leave your flashlights/phones/anything that lights up at home – if you must bring a flashlight, put a red filter on it. It takes a while (about 20 minutes, usually) for your vision to adapt to the dark, and the more adapted your vision is, the more you’ll be able to see. Staring at your iPhone will ruin it for you as well as whoever you’re with.
  • Lie down on the ground. If you stand or sit and look up, you can hurt your neck. Plus, lying down gives you the best view.
  • Lay in silence and watch the sky. Think, or don’t think. Watch.

Be prepared. Go out. Look up.


2 thoughts on “A Barrage of ‘Shooting Stars’

  1. I had never learned about the radiant point before (never having seen a meteor shower, yet). That really piqued my interest, and it spurred me to read about perspective on Wikipedia. So, thanks for exposing me to a cool thing.

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