Perseid meteors streak past stars in the night sky near Amman, Jordan, in the early hours of August 12, 2004. The Perseid meteor shower is sparked every August when the Earth passes through a stream of space debris left by Comet Swift-Tuttle, and was clearly visible to the naked eye in several parts of the Middle East and Asia.
| Photo Credit: Ali Jarekji/Reuters

The Perseid meteor shower this year began around July and will last until late August, but their peak activity is going on now — between August 11 and 13. The shower should be visible to the naked eye in many places between midnight and dawn, especially in the northern hemisphere. Local weather conditions could affect this, however.

A meteor shower is a raining-down of meteors over the earth from space at a particular time of year. The Perseid meteors are debris left behind by the comet Swift-Tuttle, which orbits the Sun in an elliptical path that takes 133 years to complete once. When the earth moves through the cloud of debris intersecting its path around the Sun, its gravity pulls the debris towards itself, producing the meteor shower.

In the 1990s, scientists studying the Swift-Tuttle comet noticed there was an important chance it could strike the earth or the moon in mid-2126. The impact could be powerful because the comet is 26 km wide. Fortunately, when scientists performed more careful calculations prompted by this concern, they found the earth was safe from a Swift-Tuttle impact for at least two millennia more.

The Perseids shower itself doesn’t threaten the earth: most meteors burn up in the atmosphere. Some that take a more tangential path through the air produce small fireballs. During its peak, the shower can produce more than 60 meteors per hour.