Perseid Meteor Shower: Peak Dates For ‘Fireballs’ Over PA Skies

EASTERN PENNSYLVANIA — The thief coronavirus has robbed Americans of many of their summer pleasures, but it can't steal the annual Perseid meteor shower as it builds to its peak, when 50 to 75 shooting stars an hour may be seen in the skies over the Philadelphia region.

Whether you’ll be able to see this dazzling show in Earth's celestial canopy depends on the weather in Southeastern Pennsylvania during the shower's Aug. 11-13 peak.

The National Weather Service says skies over the next week will be variably cloudy, though Sunday and Monday nights are forecast to have clear skies for viewing.

The hours between midnight and sunrise are the best time to scan the sky for the summertime classic, which is known to produce fireballs. The moon is in its last quarter phase, and that will mar the sky show a bit. But the Perseids tend to be bright, so you should be able to see a fair number of them.

The brightest of meteors are known as “fireballs,” and they’re at least as bright as the planets Jupiter or Venus. NASA meteor expert Bill Cooke says the Perseids produce more fireballs than any other meteor shower—to the extent that he's nicknamed them the "fireball champion." During the Perseids, it's not unusual to see a fireball every few hours, Cooke says.

NASA's research suggests the Perseids are rich in fireballs because of the size of Swift/Tuttle's nucleus—about 16 miles (or 26 kilometers) in diameter.

"Most other comets are much smaller, with nuclei only a few kilometers across. As a result, Comet Swift-Tuttle produces a large number of meteoroids, many of which are large enough to produce fireballs," he wrote for NASA.

Though viewing is best after midnight from anywhere in the sky, the evening hours may offer a special treat known as an earthgrazer. They're rare, but a sight to behold—a long, slow and colorful meteor that streaks horizontally across the sky.

The peak dates aren't the only time to see the Perseids, which have been streaking across the sky since mid-July and will continue through Aug. 24. So consider watching past the peak dates, and especially after Aug. 17, when moonless skies prevail, according to Earthsky.org.

The rambling Delta Aquarid meteor shower continues through mid-month, so you may see a few of those, too. The Delta Aquarids are not as prolific as the Perseids, but up to 10 percent of them leave persistent trains—that is, glowing ionized gas trails that can last for a second or two after the meteor passes.

Either shower can be seen from anywhere in the sky, though Earthsky.org advises placing yourself in the moon's shadow near a barn or other structure. The meteors will be more visible.

The other thing required for successful meteor watching is patience. NASA’s Cooke told Space.com meteor shower watching requires an investment in preparation and time, but is "the simplest form of astronomy there is."