The upcoming solar eclipse may be getting the lion's share of attention among astronomers this month, but what may be the year's most popular meteor shower is peaking this weekend, and for many will likely be worth a trip outside at night.
The Perseid meteor shower reaches its peak Friday and Saturday.
For skywatchers, there is some good news and some bad news.
The bad news is that the moon will be about three-quarters full, obscuring many of the fainter meteors. However, there will be a slightly higher number of falling meteors this year than normal, and many of the brighter ones should be visible in a dark enough sky.
"Observers this year could probably expect to see one about every couple of minutes," said Bill Cooke, lead of NASA's Meteoroid Environment Office at Marshall Space Center.
During a good Perseid shower with ideal viewing conditions, viewers would see roughly twice that many.
The Perseid shower in 2016, for example, featured an especially large number of meteors — the phenomenon is known as an outburst, Cooke said.
This year's expected number of 150 per hour, a bit higher than the typical range of 80-100 an hour, may be a consequence of last year's outburst, he said.
It is far from a record. For example, the 1993 Perseids delivered about 300 meteors per hour. And some Leonid showers have numbered an estimated 100,000 meteors in an hour.
"The Leonids have produced the ones that led people to think the world was going to end," Cooke said. "Imagine going outside in 1833 and seeing tens of meteors per second."
There is a reason for the irregularity.
Comets shed bits of dirt, ice and rock as they make their elliptical orbits from the outer solar system toward the sun and back out again. These bits of debris become meteors when they collide with the atmosphere of Earth on its own orbital path, burning up on entry.
Sometimes, the gravitational pull of the larger planets in the solar system — especially Jupiter — can warp the comet tail's orbit, and pull it closer to Earth. This brings more material into Earth's orbital path.
But it will still be worth a look, and there are things viewers can do to obtain the best possible view. Turning away from the light of the moon will help, or sit in a place where the moonlight is blocked by trees, for example.
For the best possible show, NASA recommends traveling to an area with little light pollution, going later at night (between 11 p.m. and 3 a.m.) and even putting a baseball cap on sideways to cut the glare of the moon.
Meteor showers are valuable to scientists because they can give researchers an idea of the comet's composition, and, by seeing how strong the shower is, a sense of the path of its orbit.
They also can powerfully illustrate the vast scale of astronomical time.
"When you go out tomorrow night," Cooke said, "the meteors you will see will be the material that left that comet around the time of the Civil War or before."