Meteor showers tonight

What a meteor shower is

Comets, and a few asteroids, shed dust along their orbits. Where Earth’s path crosses one of these streams, the planet runs into the grains each year on about the same dates. Many visible meteors come from particles between the size of a sand grain and a small pebble. The American Meteor Society says they hit the atmosphere at between about 25,000 and 160,000 mph and burn up 50 to 75 miles above the ground, each leaving a brief streak of light.

Because the grains travel on parallel paths, their streaks seem to spread out from one point in the sky, the radiant. A shower is named after the constellation that holds its radiant, but the meteors can appear anywhere overhead. You don’t need to look at the radiant; a wide, dark view of the sky works best.

ZHR and what you will actually see

Each shower is listed with a ZHR, or zenithal hourly rate. This is the number one observer would see in an hour under a perfectly dark sky with the radiant directly overhead. It is a standard measure of a shower’s strength, not a forecast for your backyard.

Real counts are lower for three reasons. The radiant is rarely overhead, and the lower it sits, the more of the shower’s meteors stay below your horizon. Light pollution hides the fainter meteors, which are the majority. And moonlight does the same. In a 2021 analysis of the Perseids, NASA’s Bill Cooke concluded that sky darkness matters more than anything else: a dark rural site can show several times as many meteors as a suburb, and a city very few. The rate we show for each shower allows for the radiant’s height at your location under a dark sky; light pollution and moonlight lower it further.

How the Moon matters

A bright Moon brightens the whole sky and can wash out all but the brightest meteors. A crescent Moon does little harm. A full or gibbous Moon is a real problem, unless it sets or rises outside the hours you plan to watch. Each shower page shows the Moon’s phase on the peak night and how much of the best window it spends above the horizon.

How we work out the best hours

For each city, our engine follows the shower’s radiant through the peak night, from the end of evening twilight (when the Sun is 12 degrees below the horizon) to the start of morning twilight. The best hours are the stretch when the radiant is at least 20 degrees up and within 15 degrees of its highest point that night. If the Moon is more than 30% lit, we move the window to the moon-free part of that stretch when there is enough of it. The full method is on our methodology page.

For what to bring and how to prepare, read our guide to watching a meteor shower.