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The Perseids Light Up the Sky

Posted on Fri, August 12, 2016
  • by: Shauna Edson, Astronomy Educator
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There's still time to catch the summer’s best meteor shower.

The annual Perseid meteor shower is at its peak (August 11-13). One of my favorite summer memories was being at 4-H camp in mid-August, in a valley far away from city lights. We all went to the baseball field to stare up at the night sky, and right away we noticed little streaks of light crossing the sky every few minutes. Meteors! I couldn’t believe how many we saw. One of them lasted almost five seconds, long enough for me to poke my friend and show her before it disappeared.

Image of the night sky wiht streaks of colorful meteors.

This long-exposure image shows many meteors streaking across the night sky. Image: NASA/JPL

 

I didn’t know it back then, but my camp happened to be during a strong annual meteor shower, the Perseids.

Meteors, or “shooting stars,” are not really stars even though they can appear just as bright. Meteors are small pieces of rock or cosmic debris that fall into the Earth’s atmosphere from outer space. A meteor travels at thousands of miles per hour, so as it collides with the molecules of gas in Earth’s atmosphere the friction causes it to heat up and even vaporize, creating the streak of light that we see. Dozens of meteors happen on Earth every day, and while they are hard to see from cities where bright lights flood the sky, people in rural areas can often spot them.

Meteor showers occur when the Earth’s orbit around the Sun takes us through a debris field, which is often a trail of cosmic dust left behind by a comet. The millions of tiny particles can create a “shower” of dozens to hundreds of meteors per hour. In this case, the Perseid meteors are debris from the comet Swift-Tuttle, which takes 133 years to complete an orbit of the Sun. Every year around August 12, the Earth flies by the trail of dust from Swift-Tuttle and we see more meteors than usual for several days.

This year the Perseids were forecasted to be particularly numerous. Exciting! But why the difference? The trail of Swift-Tuttle comet dust can be influenced by the gravity of large objects in our solar system. Jupiter recently passed by the debris field and pulled it a little closer to Earth’s orbital path. Usually the Earth just brushes past the debris field, but this year we may be passing right through it, which could mean a really spectacular show in the summer sky. The most action was expected on August 11 and 12 between midnight and dawn, but meteors should be visible through the weekend.

The best way to view a meteor shower is always the same; get away from the city to a place with dark skies, find a flat area with few trees or buildings, then lie back and let your eyes take in the whole sky. Any time a streak of light appears, your eyes will go right to it because you’ll sense the movement. Telescopes or binoculars aren’t really helpful for seeing meteors, but they are great for looking at other objects (like Mars and Saturn, which are very bright in the south) while you wait for shooting stars. 

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