The Eta Aquarids might be the best meteor shower that you’ve never heard of. This shower is caused by flecks of dust released from the nucleus of Halley’s Comet. It stays near full strength for five days — longer than any comparably intense shower — and its meteors are bright and plentiful.
So why isn’t it better known?
If you live in the Southern Hemisphere, where this is arguably the year’s best meteor shower, you’ve very likely heard of it. But relatively few Eta Aquarids are visible from mid-northern latitudes, where the lion’s share of amateur astronomers live. Still, this shower puts on quite a respectable show in the southernmost tier of the United States. And because the meteors are so bright, they’re occasionally seen much farther north than that during morning twilight — and even broad daylight.
Conditions are ideal for the Eta Aquarids this year, because the Moon is new or very thin throughout the shower’s peak. If you’re watching the Eta Aquarids on the morning of Sunday, May 4th, see if you can spot the very thin crescent Moon as the sky gets light. See our article on opposing crescent Moons to find out why this is such an unusual opportunity.
As the name Eta Aquarids suggests, all of this shower’s meteors appear to radiate from a spot near the northeastern corner of the constellation Aquarius. The higher a shower’s radiant is in the sky, the more meteors you can see, and you won’t see any meteors at all when the radiant is significantly below the horizon.
In the case of the Eta Aquarids, the radiant doesn’t rise until long after midnight, and it reaches its highest in the sky well after sunrise. So the best time to watch for meteors is anywhere from one to two hours before sunrise. Earlier than that, the radiant is too low — any later, the sky is too bright.
Be on the lookout for a rush of meteors before dawn Monday morning. That’s when the annual Eta Aquarid meteor shower reaches maximum activity. Seeing the shower with no interference from the Moon is nice, but there’s a possible bonus. Astronomers think the Eta Aquarids could produce more than twice the usual number of meteors.
Meteors are fleeting fiery trails — “shooting stars” — that occur as small solid particles burn up in Earth’s atmosphere. Comets shed dust as ice boils off their surfaces and litter their orbits with debris. Meteor showers result when Earth grazes a comet’s dusty path and sweeps up some of these particles. Dust shed by Comet 1P/Halley creates the Eta Aquarid shower, so named because the meteors seem to emanate from a common point, or radiant, near the star Eta in the constellation Aquarius.
Meteor-watching is a minimalist activity. No equipment is required — skygazers just need to know when and where to look. Dress warmly, relax in a comfortable chair, and keep an eye on the southeastern sky. It’s kind of like fishing.
|In Halley’s dust
Astronomers give a shower’s meteor rate using numbers that express the number of meteors seen each hour by an observer viewing under a clear, dark sky when the radiant is overhead. In most years, by this measure, the Eta Aquarid shower rates 30 meteors per hour. But the radiant never gets overhead before dawn, so observers typically will see far fewer meteors.This year, though, the rate could more than double. Studies suggest the shower’s rates rise and fall in a 12-year cycle. This period hints that Jupiter, the solar system’s largest planet, is affecting the debris that creates the shower.
Jupiter orbits the Sun in just under 12 years. Every time it passes closest to the Eta Aquarid track, the orbiting particles feel an extra-strong tug. This results in a wavy track that sometimes places extra dust in Earth’s way.
|Catch a falling star
The Eta Aquarid shower is best for Southern Hemisphere observers, and the view gets worse the farther north you go. In the United States, the radiant stands only about 15° high in the southeast at 4 A.M. local daylight time. This low altitude will cut the number of visible meteors significantly. Even so, observers can expect a nice show.The shower produces pleasingly fast and often bright meteors. About 30 percent of the meteors leave behind dimly glowing trails called persistent trains. Some can be seen for as long as a minute.
Although the radiant’s low altitude reduces the number of observable meteors for northern observers, there is compensation. Eta Aquarid meteors tend to follow long paths across the sky.
|Eta Aquarid meteor shower fast facts