Our universe might be chock-full of cosmic wonder, but only a fraction of astronomical phenomena can be seen with the naked eye. Meteor showers, natural fireworks that streak brightly across the night sky, are one of them.
The end of July brings two meteor showers that will peak on the same night. One is called the Alpha Capricornids, which has been active since July 3 and is forecast to continue through Aug. 15. The other, known as the Southern Delta Aquarids, sometimes spelled Aquariids, began on July 12 and is expected to run through Aug. 23.
Both showers crest on July 30 to 31, or Thursday night into Friday morning. But the two aren’t related.
“That’s just a coincidence,” Kate Minker, an astronomer at Lowell Observatory in Arizona, said of the date. “It varies a little bit year to year.”
That they are active on the same night is one of the few things these showers have in common. The Southern Delta Aquarids is strong, producing around 25 meteors per hour, but faint. In contrast, the Alpha Capricornids yields only about five streaks per hour, and its fireballs are slow and bright.
Stargazers hoping to catch these showers at their most active may have to contend with the brightness of the moon, which will be 98 percent full. You can get a hint at when to best watch for fireballs using this tool, which relies on data from the Global Meteor Network to show activity levels in real time.
Where meteor showers come from
There is a chance you might see a meteor on any night, but you are most likely to catch one during a shower. Meteor showers occur when Earth passes through the rubble trailing a comet or an asteroid that orbits the sun. This debris, which can be as small as a grain of sand, leaves a glowing stream of light as it burns up in Earth’s atmosphere.
Meteor showers happen around the same time every year and can last for days or weeks. But each shower is at its peak for only a small window, when Earth reaches the densest part of the cosmic debris. The peak is the best time to look for a shower. From our vantage on Earth, the meteors will appear to come from the same point in the sky.
The Alpha Capricornids, for instance, will radiate from the constellation Capricornus and be visible in both the Northern and Southern Hemisphere. The Southern Delta Aquarids will originate from Aquarius and will be best seen from the southern tropics.
According to Dr. Minker, stargazers may also catch stray meteors that aren’t a part of the Alpha Capricornids or the Southern Delta Aquarids. “If you’re seeing meteors all coming from the same direction, that’s a good sign that it’s a shower,” she said.
How to watch a meteor shower
Michelle Nichols, the director of public observing at the Adler Planetarium in Chicago, recommends avoiding the use of telescopes or binoculars while watching a meteor shower.
“You just need your eyes and, ideally, a dark sky,” she said.
That’s because meteors can shoot across large swaths of the sky, so observing equipment can limit your field of view.
Some showers are strong enough to produce up to 100 streaks an hour, according to the American Meteor Society, although you probably won’t see that many.
“Almost everybody is under a light-polluted sky,” Ms. Nichols said. “You may think you’re under a dark sky, but in reality, even in a small town, you can have bright lights nearby.”
Planetariums, local astronomy clubs or maps like this one can help you figure out where to go to escape excessive light. The best conditions for catching a meteor shower are a clear sky with no moon or cloud cover, sometime between midnight and sunrise. (Moonlight, like light pollution, washes out fainter sources of light in the sky.) Make sure to give your eyes at least 30 minutes to adjust to seeing in the dark.
Ms. Nichols also recommends wearing layers, even during the summer. “You’re going to be sitting there for quite a while, watching,” she said. “It’s going to get chilly, even in August.”
Bring a cup of cocoa or tea for more warmth. Then lie back, scan the sky and enjoy the show.
