On the evening of August 12th and early on August 13th, the Perseid meteor shower will reach its peak, with streaks of light zooming across the skies up to once every minute or so. Unfortunately, stargazers may have a tough time seeing these shooting stars this year, thanks to the light of our pesky Moon.
The Perseid meteor shower occurs every August whenever Earth passes through the tail of a comet called Swift-Tuttle, a big rock about 16 miles (26 kilometers) across that orbits around the Sun. As Swift-Tuttle zooms through space, the Sun heats up the icy comet, causing a bunch of loose material like pebbles and dust to fly off. This debris forms a cloud all along Swift-Tuttle’s orbital path around the Sun. The Earth barrels through this cloud at the same time every year, resulting in a bombardment of debris that reaches speeds of between 25,000 and 100,000 miles an hour.
“We’re not expecting a sort of once-in-a-lifetime, ‘Oh my gosh, the sky will be full of shooting stars,’ [event].”
These tiny meteors pose no threat to us on Earth. They’re so small — about the size of sand or rice — and they come in so fast that they burn up completely when passing through the thick atmosphere around our planet. “They hit the upper atmosphere, and all of a sudden, they’re going through some gases, they heat up with friction, and then they glow,” Michelle Thaller, an astronomer and research scientist at NASA’s Goddard Spaceflight Center, tells The Verge. “And so you get these wonderful streaks of light.” The streaks get their name from the fact that they look like they’re coming from the constellation Perseus when they whizz through the sky.
The night of August 12th is when Earth passes through the densest part of the Swift-Tuttle debris cloud, leading to the most frequent streaks of light. But this year, the full Moon is just a few days away, so our lunar neighbor is almost fully illuminated. That means the sky is very bright with light reflected off the Moon, which will make any Perseid meteors more difficult to see. “We’re not expecting a sort of once-in-a-lifetime, ‘Oh my gosh, the sky will be full of shooting stars,’ [event],” says Thaller. “It won’t be like that.”
That doesn’t mean you should completely stay indoors, says Thaller, as a few meteors will be bright enough to get past the Moon’s glow. And if this year’s event turns out to be a true bust, there’s always next year. The Perseids occur at the same time every year, and in 2020, the Moon will be way less bright. So if the lunar light blows out tonight’s show, come back next year to try again.