Comets Provide Some of the Most Spectacular Sky Shows
By Scott Levine
Through July, most of the space news has been full of extraordinary stories and gorgeous photos of the alluringly named comet C/2020 F3 (NEOWISE), which was visible with the naked eye even in Westchester’s skies.
Comets are balls of dirt and rock, held together by water and other exotic ices that spend their time speeding through the solar system in orbits that are long, like a stretched rubber band. These paths take them very far from the sun at one end, and extremely close at the other. As they near the sun, some of the material in them heats up – or outgasses – and creates that long tail we all think of.
Comet NEOWISE is on its way out of view now, and it won’t be back to our part of the solar system for more than 6,500 years. But that might not be the end of its story.
As comets thaw, they also leave behind a trail of rocks and dust. We call these leftovers meteoroids as they travel through space. Several times a year, Earth passes through these trails where our orbits cross. Some of those bits, mostly about the size of grains of sand, burn up and streak across the upper reaches of our atmosphere, what we call meteors or shooting stars. If one manages to make it all the way to the ground, we call it a meteorite. They’re the same thing, but with different names for where they are and how we experience them.
Every summer, we catch up with the leftovers from Comet Swift-Tuttle, which last passed through our neighborhood in 1992. As we do, we’re treated to the famous Perseid meteor shower, which peaks around Aug. 11 each year.
Meteor showers are named for their radiant, the region of the sky most of the meteors appear to emanate from. In the case of the Perseids, that’s the constellation Perseus, which rises into the northeast late at night. They don’t all come from that area, but it’s a helpful starting point. That said, the later you can stay awake, the higher in the sky Perseus will be, and the easier it will be to see more meteors.
To watch, simply head out to a comfortable north-facing spot once the stars are out. Bring a chair, give your eyes a chance to adjust to the dark and look up. No telescope or binoculars are needed; in fact, they’ll get in the way, but of course you can use them to look at other things.
Perseus’s stars might be a little hard to find, so if you can spot the Big Dipper toward the northwest, and then just turn your chair toward the right, you’ll be facing the right direction.
These showers are unpredictable, but this year, there’s a chance for a good show. Twenty meteors per hour isn’t out of the question. The night of the peak, the moon will be at its last-quarter phase (its left-hand side lit), and won’t rise until around 1 a.m. on Aug. 12. So, its light might not interfere too much. Time will tell, and it’s certainly worth a try.
Comets like NEOWISE are few and far between, but maybe we’ll see it again as a meteor shower sometime. I hope you’ll take a look.
Scott Levine (astroscott@yahoo.com) is an astronomy writer and speaker from Croton-on-Hudson. He is also a member of the Westchester Amateur Astronomers, which is dedicated to astronomy outreach in our area. For information about the club, including membership, newsletters, upcoming meetings and lectures at Pace University and star parties at Ward Pound Ridge Reservation, visit westchesterastronomers.org. Events are free and open to the public. Please note: All in-person club activities are suspended until further notice due to COVID-19.
