Perseid meteor shower is now under way

The shower will peak August 12-13, with up to 150 meteors visible per hour at dark sky sites.
By Laurel Kornfeld | Jul 28, 2017
The annual Perseid meteor shower has begun, with a good view expected in the northern hemisphere between July 17 and August 24.

Meteor showers come from debris ejected by asteroids and comets. Perseid meteors are remnants of Comet 109/Swift-Tuttle, which has an orbital period of 133 years.

Earth experiences a meteor shower every year when the planet crosses the orbital path of the parent comet.

When clouds of debris particles, most no larger than a grain of sand, enter Earth's atmosphere, they burn up, producing bright streaks.

While in space, these particles are called meteoroids. Once they hit Earth's atmosphere, they become meteors. Those parts of meteors that survive to hit the ground are known as meteorites.

In a meteor shower, the meteors all appear to radiate from a common point, known as the radiant. For the Perseids, the radiant is in the constellation Perseus, which rises in the northeastern sky early in the evening and is high up in the sky in a slightly eastward direction before dawn.

Perseid meteors are often called fireballs because they produce long, brightly colored arcs of light.

On the nights of August 12 and 13, the shower reaches its peak, and viewers in dark sky areas away from light pollution can see as many as 150 meteors an hour.

Meteor showers are best viewed between midnight and dawn when the radiant is high in the sky.

Because the Moon will be three-quarters full on the meteor shower's peak nights, observers should search for viewing locations where moonlight is blocked.

Southern hemisphere dwellers in areas near the equator will also be able to see the Perseids, but the meteors will appear low on the horizon.


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