Halley’s Comet won’t appear in the night skies until 2061. But this week, look to the skies as our planet passes through the comet's tail for a glimpse at the annual Eta Aquarid meteor shower.
The meteor shower gets its name from Eta Aquarii, a star in the Aquarius constellation from which it appears to emanate. However, like the Orionid meteor shower in the fall, the bright flashes form as bits of dust, rock and ice left in the wake of Halley’s Comet burn up in Earth's atmosphere.
While it usually takes from mid-April to mid-May to traverse the tail's width, the Eta Aquarid meteor shower will most likely peak on May 5 or 6 as our planet plows through the thickest part. According to NASA, some meteors may be visible starting the evening of May 4.
Apart from their origins as remnants of Halley’s Comet, the Eta Aquarids are also known for the speed at which they enter our atmosphere. As our planet swoops through the dust cloud, particles and chunks of rock will smash into the upper atmosphere at almost 150,000 miles per hour, Bruce McClure writes for EarthSky.org. Thanks to this speed, about half of the meteors in the shower leave behind “persistent trains”—trails of ionized gas that glow for several seconds after the meteor has burned up.
While the Eta Aquarids have existed for centuries, the meteor shower was only discovered relatively recently. The first sign of the meteor shower in recent times was noticed by the astronomer Hubert Anson Newton in the late 1800s, who identified hints of a recurring spring shower in astronomical accounts dating back centuries.
No one officially witnessed the meteor shower until 1870. And even then, it took another six years before astronomers finally made the connection between the Eta Aquarids and Halley’s Comet, Elizabeth Howell reported for Space.com.
"For most observers, the Eta Aquarids are only visible during the last couple hours before the start of morning twilight," the American Meteor Society told Howell. "The reason for this is that the radiant is situated approximately 60 degrees west of the sun. Therefore, it rises before the sun in the morning hours."
Luckily for stargazers, they won’t have to contend with moonlight when trying to take a look at the meteor shower this year. The peak of the Eta Aquarids will take place during a new moon, which means the meteors should pop out more against the dark sky. Intriguingly, the new moon will occur as it is at its closest to Earth, making it a supermoon as well, though it won’t be visible to the naked eye, McClure writes.
The best views of the Eta Aquarids will be in the southern hemisphere and in the tropical and subtropical regions of North America, but some meteors may still be seen in parts of the United States. While viewers in North America may see about 10 meteors an hour, people watching in the southern hemisphere could see as many as 20 to 40 meteors per hour, possibly more, McClure writes. The shower should begin peaking at about 3 A.M. on May 6 and should last until dawn.
If you’re lucky enough to get a look, it could be one of the year’s most spectacular displays.