All year long as Earth revolves around the sun, it passes through streams of cosmic debris. The resulting meteor showers can light up night skies from dusk to dawn, and if you’re lucky you might be able to catch a glimpse.
The next shower you might be able to see is the Perseids. Active July 17 through Aug. 24, they will reach their peak of activity Wednesday night into Thursday morning, or Aug. 11-12.
The Perseids light up the night sky when Earth runs into pieces of cosmic debris left behind by Comet Swift-Tuttle. The dirty snowball is 17 miles wide and takes about 133 years to orbit the sun. Its last go-round was in 1992.
Between as many as 160 and 200 meteors dazzle in Earth’s atmosphere every hour during the display’s peak. They zoom through the atmosphere at around 133,000 miles per hour and burst about 60 miles overhead. The moon is not too full right now, which could make for good viewing, with the shower most active in pre-dawn hours according to the International Meteor Organization.
Where meteor showers come from
If you spot a meteor shower, what you’re usually seeing is an icy comet’s leftovers that crash into Earth’s atmosphere. Comets are sort of like dirty snowballs: As they travel through the solar system, they leave behind a dusty trail of rocks and ice that lingers in space long after they leave. When Earth passes through these cascades of comet waste, the bits of debris — which can be as small as grains of sand — pierce the sky at such speeds that they burst, creating a celestial fireworks display.
A general rule of thumb with meteor showers: You are never watching the Earth cross into remnants from a comet’s most recent orbit. Instead, the burning bits come from the previous passes. So for the Perseid meteor shower, you are seeing meteors ejected from when its parent comet, Comet Swift-Tuttle, visited in 1862 or earlier, not from its most recent pass in 1992.
That’s because it takes time for debris from a comet’s orbit to drift into a position where it intersects with Earth’s orbit, according to Bill Cooke, an astronomer with NASA’s Meteoroid Environment Office.
How to watch
The best way to see a meteor shower is to get to a location that has a clear view of the entire night sky. Ideally, that would be somewhere with dark skies, away from city lights and traffic. To maximize your chances of catching the show, look for a spot that offers a wide, unobstructed view.
Bits and pieces of meteor showers are visible for a certain period of time, but they really peak visibly from dusk to dawn on a given few days. Those days are when Earth’s orbit crosses through the thickest part of the cosmic stream. Meteor showers can vary in their peak times, with some reaching their maximums for only a few hours and others for several nights.