Every year at approximately this time, the Earth orbits through the dusty debris of Comet Swift-Tuttle. The cloud of dust particles were blasted into space from the comet's nucleus during its 133 year-long orbit of the sun.
So, every year, we can expect these tiny particles to slam into the Earth's upper atmosphere at 60 times the speed of the fastest bullet, creating a bright flash of ionization in atmospheric gases. These streaks are the meteors (or "shooting stars") you may be lucky enough to see on the ground.
NEWS: Look Up! The Perseids Are Coming
Late last night and into the early hours of this morning (Aug. 11/12), skywatchers with clear skies reported plenty of activity with more shooting stars predicted for tonight. To keep tabs on meteor activity and to report your own sightings, check in on the Meteorwatch website. For more on how to observe the Perseids be sure to read in-house astronomer Mark Thompson's excellent article on the topic.