PHILADELPHIA - The annual August meteor shower continues to peak overnight. Most meteor showers are caused by comets.
Comets are chunks of rock smaller than an asteroid.As the comets move through space, they leave a trail of rock dust. If you've ever seen a picture of a comet, the rock dust is what looks like a tail behind the comet.Each year, the Earth runs into that rock dust trail as it moves around the sun.
The rock dust is in the same spot, which is why the meteor showers happen every year at the same time.The rock dust is pretty tiny.
The dust particles are often the size of grains of sand.As that dust falls through our air, it encounters a lot of air resistance and it ultimately agitates the air.The dust agitating the air is similar to rubbing a balloon on your head: it creates charges.Your hair stands up after a balloon rubs it because that agitation receives negative changes to build up at the tip of each piece of hair.