It’s been 38 years since Halley’s Comet last passed through the inner solar system. This famous comet takes about 75 years to orbit the sun. But if you’re 42 or younger, you probably have little or no memory of this famous cosmic vagabond’s appearance in 1986 (your next chance comes in the summer of 2061).
Or perhaps, if you were there at the time, you didn’t see Halley at all because of the light pollution or the comet’s low altitude above the horizon. If you missed the 1986 event, or don’t want to wait until 2061, you might want to get out before sunrise in the next few mornings and try to get an image of some “cosmic debris” left in space by Halley’s Comet.
The orbit of Halley’s Comet closely approximates Earth’s orbit in two places. One point is in mid to late October and produces a meteor display known as the Orionids. The other point comes in early May and produces the Eta Aquarid meteors.
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When and where to watch
This year’s Eta Aquarid meteor shower is expected to be at its best on Sunday morning, May 5, when the moon is a very thin (8% illuminated) waning crescent and safely out of danger to cause any visibility disruption.
This mid-spring meteor display stays above a quarter of its peak strength for about ten days. And the 2024 version of this shower is also expected to produce a higher number of meteors than normal. More about that later.
This is the best meteor shower of the year for those living in the Southern Hemisphere, with hourly rates typically of 60 or more.
However, there is a slight drawback if you plan to observe these meteors north of the equator. The radiant (the point from which these meteors appear to appear in the sky) is found in the “Water Jar” asterism of the constellation Aquarius, which rises above the southeastern horizon around 3 a.m. local daylight time and never gets very high. as seen from northern temperate latitudes.
This means that the actual observed rates are usually lower than the often mentioned 60 per hour; closer to 10 to 20 per hour around 40 degrees north latitude (Philadelphia) to perhaps 20 to 40 per hour near 25 degrees north latitude (Brownsville, TX).
More activity in 2024?
According to the Royal Astronomical Society of Canada’s 2024 Observer’s Handbook, this year’s Eta Aquarids are “expected to feature a noticeable outburst” of meteoroids ejected from Halley’s Comet about 2,500 years ago.
In a technical article published in the August 11, 2020 issue of Astronomy & Astrophysics magazine, astronomer Auriane Egal and four colleagues from the University of Western Ontario present a new numerical model of the Eta Aquarid and Orionid meteor showers (called the “Halleyids” meteor shower in the paper).
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According to Dr. Egal and her colleagues are material ejected from Halley’s Comet, mainly in 983 B.C., with several smaller particle ejections during the cometary appearances in 1058 B.C., 835 B.C. Jupiter’s gravitational pull should lead to a 2024 larger Eta Aquarid activity.
Earth is expected to pass closest to this ‘debris river’ on May 5 around 1:30 PM UT. Unfortunately, it will be daylight over Europe and North America, but it is hoped that noticeably increased activity will perhaps continue for a few more days. on either side of this predicted peak.
The number of meteors that can be seen could be that many two or three times the normal rate for the 2024 Eta Aquarids. In their paper, Egal et al. write that this year’s outburst “could produce 120 to 160 meteors per hour, with a 30% confidence on the predicted rate.”
Catch an Earthgrazer
For most who live in the northern latitudes, the best hope may not necessarily be to see a large number of meteors, but rather to catch a glimpse of a meteor emerging from the Eta Aquarid radiation and entering the atmosphere of the will cross the earth horizontally – much like an insect skimming the side window of a car. Meteor watchers call such shooting stars ‘earth grazers’. They tend to leave colorful, long-lasting marks.
“These meteors are extremely long,” says Robert Lunsford of the International Meteor Organization. “They tend to hug the horizon rather than shooting overhead where most cameras are pointed.”
“Earth grazers are rarely plentiful,” warns Bill Cooke, a member of the Marshall Space Flight Center’s Space Environments team. “But even if you only see a few, you’ll probably remember them.”
With the forecast of increased activity on the table for Sunday (May 5), you may have a better chance of seeing more than a few Earthgrazers in the two hours leading up to first light. If you plan to watch, sit on a long lounge or deck chair, dress warmly, and focus on that part of the sky from above and down toward the southeast. Also consider trying again on Monday morning (May 6) when local skies are clear.
Comet crumbs
If you see an Earthgrazer early that morning, keep in mind that you will likely see the glowing streak produced by material coming from the nucleus of Halley’s Comet. When these tiny cometary crumbs – probably no larger than a grain of sand or a pebble – collide with Earth, friction with our atmosphere turns them into white heat, causing the effect colloquially called “shooting stars.”
So it is that the shooting stars that we have come to call the Eta Aquarids are actually an encounter with the traces of a famous visitor from the depths of space and from the beginning of creation.
Editor’s Note: If you take a great photo of the Eta Aquarid meteor shower that you would like to share with us and our news partners for a possible story or photo gallery, please send images and comments to us spacephotos@space.com.
Joe Rao is an instructor and guest lecturer in New York Hayden Planetarium. He prescribes on astronomy Natural history magazinethe Farmer’s almanac and other publications.