Meteor Showers and Where They Come From

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How Meteor Showers Work

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A Perseid meteor over the Very Large Telescope array in Chile. ESO / Stephane Guisard

Have you ever observed a meteor shower? If so, you've watched small bits of solar system history, streaming from comets and asteroids (which formed some 4.5 billion years ago) get vaporized as they crashed through our atmosphere. 

Meteor Showers Occur Each Month

More than two dozen times a year, Earth plunges through a stream of debris left behind in space by an orbiting comet (or more rarely, the breakup of an asteroid). When this happens, we see swarms of meteors flash through the sky. They seem to emanate from the same area of the sky called a "radiant". These events are called meteor showers, and they can sometimes produce dozens or hundreds of streaks of light in an hour. 

The meteroid streams that produce showers contain chunks of ice, bits of dust, and pieces of rock the size of small pebbles. They stream away from their "home" comets as the cometary nucleus gets close to the Sun in its orbit.The Sun warms the icy nucleus (which likely originated from the Kuiper Belt or the Oort Cloud), and that frees up the ices and rocky bits to spread out behind the comet. (To see the nucleus of a comet up close, check out this story about Comet 67P/Churyumov-Gerasimenko.) Some streams come from asteroids. 

Earth doesn't always intersect all the meteoroid streams in its region, but there are around 21 or so streams it does encounter. These are the sources of the best-known meteor showers. Such showers occur when the cometary and asteroid debris left behind actually slams into our atmosphere. The pieces of rock and dust get heated by friction and begin to glow. Most of the cometary and asteroid debris vaporizes high above the ground, and that is what we see as a meteroid passes through our sky. We call that flare a meteor. If a piece of the meteoroid happens to survive the trip and falls to the ground, it is then known as a meteorite. 

From the ground our perspective makes it look as though all the meteors from a specific shower are coming from the same point in the sky—called the radiant. Think of it like driving through a dust cloud or a snowstorm. Particles of dust or snowflakes appear to come at you from the same point in space. It's the same with meteor showers. 

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Try Your Luck at Observing Meteor Showers

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The streak of a Leonid Meteor as seen by an observer at the Atacama Large Millimeter Array in Chile. European Southern Observatory/C. Malin.

Here's a list of meteor showers that produce bright events and can be seen from Earth throughout the year. 

  • Quadrantids: these begin in late December and peak in early January each year. This stream is made up of particles from the breakup of an asteroid called EH1. If conditions are good, observers might see over 100 meteors per hour. Its meteors appear to stream from the constellation Boötes.
  • Lyrids: are a mid-to-late April shower and usually peak around the 22nd. Observers are likely to see 1-2 dozen meteors per hour. Its meteors appear to come from the direction of the constellation Lyra.
  • Eta Aquarids: this shower begins around the 20th of April and lasts into late May, peaking around May 5th. It is the stream left behind by Comet 1P/Halley. Observers can expect to see upwards of 60 or so meteors per hour, depending on viewing conditions. These meteors seem to stream from the direction of the constellation Aquarius.
  • Perseids: This is a famous shower that has its radiant in the constellation Perseus. The shower begins around the middle of July and extends through late August. The peak is around the 12th of August, and you might see up to 100 meteors per hour. This shower is the stream left behind by the comet 109P/Swift-Tuttle.
  • Orionids: This shower begins on October 2 and lasts into the first week of November, peaking around the 21st of October. The radiant of this shower is the constellation Orion
  • Leonids: Another well-known meteor shower, this one is created by debris the comet 55P/Tempel-Tuttle. Look for its meteors beginning November 15th through the 20th, with a peak on November 18th. Its radiant is the constellation Leo. 
  • Geminids: this shower begins around the 7th of December, radiates from Gemini, and lasts for about a week. If conditions are very good, observers might see about 120 meteors per hour. 

Although you can see meteors any time of night, the best time to experience meteor showers is usually in the early morning hours, preferably when the Moon isn't interfering and washing out the dimmer meteors. They'll appear to be streaming across the sky from the direction of their radiant.