What is the source of the Perseid meteor shower?
I hope you've been looking at the night sky lately! If not, stay up late and catch the Perseid Meteor show! It happens every August, and this year it has been spectacular! It peaked last night, so sorry I didn't give you a better heads up, but it visible for another 10 days, so check it out (it's best after midnight to the Northeast).
If you trace all the Perseid meteors backward, they all seem to come from the constellation Perseus, near the famous Double Cluster (furtherest star to the left in the Perseus constellation). Hence, the meteor shower is named in honor of the constellation Perseus the Hero.
However, despite it's name, this is a chance alignment of the meteor shower radiant with the constellation Perseus. The stars in Perseus are light-years distant while these meteors burn up only about 60 miles (100 km) above the Earth’s surface.
In ancient Greek star lore, Perseus is the son of the god Zeus and the mortal Danaë. It is said that the Perseid shower commemorates the time when Zeus visited Danaë, the mother of Perseus, in a shower of gold.
Every year, from around July 17 to August 24, our planet Earth crosses the orbital path of Comet Swift-Tuttle, the parent of the Perseid meteor shower. Debris from this comet litters the comet’s orbit, but we don’t really get into the thick of the comet rubble until after the first week of August. The bits and pieces from Comet Swift-Tuttle slam into the Earth’s upper atmosphere at some 130,000 miles (210,000 km) per hour, lighting up the nighttime with fast-moving Perseid meteors.
Comet Swift-Tuttle has a very eccentric (oblong) orbit that takes the comet outside the orbit of Pluto when farthest from the sun, and inside the Earth’s orbit when closest to the sun. It orbits the sun in a period of about 133 years. Every time this comet passes through the inner solar system, the sun warms and softens up the ices in the comet, causing it to release fresh comet material into its orbital stream.
Comet Swift-Tuttle last reached perihelion (closest point to the sun) in December 1992 and will do so next in July 2126.