A Halley's Comet meteor shower peaks early tomorrow morning
You may spot pieces of a famous comet streaking through the sky early Tuesday morning.
The eta Aquariid meteor shower is reaching its peak, so check for clear weather and get out before the sun rises for a chance to see pieces of Halley's comet flash through the sky.
Each year, from mid-April through until the end of May, our planet passes through a stream of ice and dust that originates from Halley's Comet. During every pass the comet makes through the inner solar system, the Sun heats it up, causing it to expel dust and ice particles out into space. Over time, this debris has stretched out along the entire span of the comet's orbit. Even now, although the comet is very far from Earth and not expected to swing past us again until 2061, we still encounter this debris stream twice as we orbit around the Sun.
Comet 1P/Halley's path through the solar system is shown here in white. The debris the comet leaves behind is represented by small white dots along and within the comet's orbit, which becomes much more concentrated closer to Earth, in this case producing the eta Aquariid meteor shower. (meteorshowers.org)
As the tiny meteoroids from the stream get swept up by Earth's atmosphere, they produce brief flashes of light in the night sky, known as meteors. At this time of year, the meteors all appear to originate from a point in the sky near the star eta Aquarii, in the constellation Aquarius. As a result, astronomers call this the eta Aquariid meteor shower or the eta Aquariids.
The best time to see the eta Aquariids is between 2 a.m. and 5 a.m. local time. That is when the radiant — the point in the sky the meteors appear to stream out of — rises with Aquarius in the pre-dawn hours.
This simulated view of the night sky shows the radiant of the eta Aquariid meteor shower, near the constellation Aquarius, above the eastern horizon on the morning of May 6, 2025. (Stellarium/Scott Sutherland)
While the eta Aquariids occur over a period of roughly a month and a half, they put on their best showing between May 3 and May 9. However, the greatest number of meteors is expected during the peak, on the morning of Tuesday, May 6.
At that time, the shower could produce between 20-40 meteors per hour. Simply because it's difficult to focus on the entire horizon at once, most observers tend to see about half that number, though. That averages out to one meteor every three to four minutes.
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Look to the east
For most meteor showers during the year, we're advised to sit back, look straight up, and take in as much of the sky above as possible. This is because meteors tend to show up randomly, and with the radiant of a meteor shower climbing higher in the sky throughout the night, the meteors can hit the atmosphere anywhere overhead.
However, the eta Aquariids are a bit different. With the radiant rising so late, it doesn't reach very high in the sky before the meteors become lost in the twilight of pre-dawn. Therefore, it's best to look low in the eastern sky for the best chance at spotting these meteors.
(Austin Human/Unsplash)
It's also possible to spot eta Aquariids even before the radiant rises.
"At this elevation meteors can still skim the upper layers of the atmosphere and will appear as long 'earthgrazers'," says Robert Lunsford from the American Meteor Society. "The condition continues at radiant rise and while the radiant lies low in the sky. As the radiant gains elevation, the meteors are able to penetrate deeper into the atmosphere creating shorter and quicker meteors."
READ MORE: How to get the most out of meteor showers and other night sky events
No lunar interference
With the First Quarter Moon rising on the fourth, this meteor shower is peaking during a Waxing Gibbous Moon. While that phase of the Moon is usually bad news for viewing meteors, in this case the timing is on our side.
The astronomical events for May 2025, including the phases of the Moon, planetary conjunctions, and meteor showers. (Scott Sutherland, moon graphics from NASA's Scientific Visualization Studio, conjunctions courtesy Stellarium)
With the Waxing Gibbous Moon setting just as the meteor shower radiant rises, we will have a moonless sky to enjoy the eta Aquariids peak. That won't even affect the earthgrazers that Lunsford mentioned, since we can turn our backs to the Moon setting in the west, to look for meteors in the east.
Persistent Trains
The eta Aquariid meteors put on a decent enough show on their own. However, observers have also reported a different phenomenon, known as persistent trains.
As Comet Halley meteoroids streak through the air at 240,000 km/h, we see the typical meteor flashes. However, after some meteors wink out, a glowing trail is left behind in their wake which can float on the wind for minutes or even hours after.
Four frames taken from a persistent train video, shot on October 21, 2022, show the initial Orionid meteor flash, and three views of the persistent train that developed in its wake. (Brenda Tate & Tim Doucette via Storyful)
Given how rarely this phenomenon has been recorded, researchers aren't sure exactly how they occur. It could be that the meteors release so much energy that they strip electrons from the air molecules they speed past. When those electrons rejoin with the air molecules, they release that extra energy as a burst of light, similar to how auroras occur. It's also possible that the train results from chemiluminescence, which is when metals vapourizing from the fast-moving meteoroid chemically react with oxygen and ozone in the atmosphere to produce light.
Two Halley's Comet meteor showers
The eta Aquariids are just the first of two meteor showers that we see each year from Halley's Comet.
Most comets tend to pass near Earth's orbit only once during each of their passes around the Sun. As Halley swings around the Sun every 75 years or so, the path it traces is at just the right angle that it intersects with Earth's orbit twice.
This diagram shows the two points when Earth passes near the path of Halley's comet, in May and October each year. Arrows indicate which direction the comet debris is travelling during each period of the year, with Earth encountering the outbound debris for the eta Aquariid meteor shower in April and May and the inbound material for the Orionid meteor shower in October. (NASA/JPL-Caltech/Scott Sutherland)
In April and May, we sweep through the 'outbound' flow of Halley's debris, which is the dust and ice that trails behind the comet after it rounds the Sun and is headed back into the depths of the solar system. Since this debris is coming at us from the direction of the Sun, we only see these meteors in the hours just before sunrise.
During the month of October, we pass through the 'inbound' flow of Halley's debris, which follows the comet's path as it approaches its closest distance to the Sun. This results in the Orionid meteor shower. With the meteoroids arriving from opposite the Sun, the Orionids last for much of the night, from around 10 p.m. and until sunrise.
Thumbnail courtesy Brenda Tate & Tim Doucette, via Storyful