- The Perseids are a meteor shower that occurs each year in late winter.
- This year, the astronomical event peaks August 12-13.
- A bright moon will make seeing the meteors more challenging, but NASA says stargazers can expect to see one every couple of minutes.
Right now Earth is ploughing through a cloud of tiny bits of comet dust, turning the rice-grain-size debris into what many call shooting stars.
Known as the Perseid meteor shower, this recurring astronomical event is easily the most-watched — and beautiful — shower of every year.
The Perseids in 2017 run from July 13 until August 24; they peak in the late evening and early morning hours of August 12 and 13.
Some websites have claimed that there will be more meteors visible per minute this year than any other time in nearly a century, but experts say this is hogwash.
“This year, we are expecting enhanced rates of about 150 per hour or so, but the increased number will be cancelled out by the bright Moon, the light of which will wash out the fainter Perseids,” Bill Cooke, who leads NASA’s Meteoroid Environment Office, wrote in an August 3 blog post.
“A meteor every couple of minutes is good, and certainly worth going outside to look, but it is hardly the ‘brightest shower in human history.'”
How to watch
This year’s conditions will be challenging for two reasons.
First, there’ll be a waning gibbous moon — the full moon will have just ended, but it will still be full and bright.
Second, the moon will rise in the evening and set near dawn. Normally the best time to watch for meteors is after the moon sets. TimeAndDate.com has a convenient moonrise and moonset tool you can use to find out when that will happen in your location.
Given this year’s conditions, the best time to head outside is between midnight and dawn. The closer to dawn the better — though twilight begins to eat up the dark sky a couple of hours before the sun rises.
You won’t need any telescopes or fancy equipment to see the meteors — just clear skies, your eyes, and a bit of patience. Find a dark, remote spot away from the light pollution of nearby towns and cities, make yourself comfortable, and set aside a good chunk of time to enjoy the show.
“Give yourself at least an hour of viewing time for watching any meteor shower,” EarthSky.org advises. “Meteors tend to come in spurts that are interspersed by lulls. Also, it can take as long as 20 minutes for your eyes to adapt to the dark.”
Perseids meteors are bright and fast, and they often leave persistent trains — the bright streaks that linger in the sky. They are best seen from the northern hemisphere. The meteors travel at the mind-numbing speed of 215,000km/h — 500 times faster than the fastest car in the world.
What causes a meteor shower?
When a comet swings too close to the sun, the sun’s light boils its icy surface, releasing particles of ice and dust.
This debris coming off the comet forms a tail that points away from the sun. As Earth crosses the orbit of this comet, we pass through the tail:
The gravity of our planet attracts the dust and ice that the comet has left in its wake. When that debris is pulled into our atmosphere, it rubs up against air molecules, causing it to burn up and streak through the sky.
That process results in the glowing trails of light that we see as meteors, or “shooting stars.”
The comet producing the meteors in the Perseids is Swift-Tuttle, a 16-mile-wide hunk of space rock that takes 133 years to orbit the sun. It’s the largest object in our solar system that makes repeated close approaches to Earth.
The meteors can appear anywhere in the sky, but if you trace their paths back, they all appear to come from the same point, called the radiant. That’s because the meteors are all approaching us at the same angle.
Meteor showers are all named after their radiant — the apparent point in the sky that the meteors come from. The radiant point for the Perseids is the constellation Perseus the Hero.
Ali Sundermier wrote a previous version of this story.