Astronomy Essentials

Best mornings for Eta Aquariid meteors likely May 5 and 6

A southwestern U.S. scene, with a seguaro cactus in silhouette, and a meteor in the sky.
Early Eta Aquariid meteor, caught by Eliot Herman in Tucson, Arizona on May 1, 2021. Thank you, Eliot!

It might seem to you as if meteor showers are one-night affairs, and, it’s true, there’s usually one late night or early morning that’ll provide the best show. But most meteors in annual showers rain down over many days, or even weeks. In 2021, the forecast for May’s Eta Aquariid shower calls for the greatest number of meteors to fall before dawn on Wednesday, May 5. The mornings around that date – May 4 and 6 – might give you a good sprinkling of meteors as well. Note phase of the moon. There’s more moon on the morning of May 4 than May 5. In 2021, on the mornings of May 5 or 6, we don’t expect the light of a waning crescent moon – rising near the time of dawn – to intrude too greatly. The moon might even add a little something to your early-morning meteor drama, as it joins up with the bright morning planets, Jupiter and Saturn, on May 4 and 5. See the chart below:

Several positions of moon by the planets Saturn and Jupiter with green ecliptic line.
Watch for the moon near Jupiter and Saturn, especially on the mornings of May 3, 4 and 5. Moonlight might somewhat hamper the viewing of the Eta Aquariid meteor shower in 2021. But there are ways to work around the moon as we explain later on in this post. Note: The moon appears larger on our sky chart than it does in the real sky.
Many short, bright radial streaks indicating meteor pathways, with glowing moon over desert horizon.
The 2013 Eta Aquariid meteor shower was fantastic as viewed from Earth’s Southern Hemisphere. Colin Legg of Australia created this composite of his experience. He wrote, “Composite of approximately 50 images containing 26 meteors, meteor train, 17% moon, zodiacal light and Pilbara desert.”
Very bright meteor streak against Milky Was, above misty valley in crater of mountain.
Meteor captured over Mount Bromo, an active volcano in Indonesia, during the 2013 Eta Aquariid shower. Photo by Justin Ng of Singapore. See more photos by Justin Ng.

The Eta Aquariid meteor shower favors the Southern Hemisphere; it ranks as one of the finest showers of the year there. At mid-northern latitudes, these meteors don’t fall so abundantly, although people in the southern states in the U.S., for example, tend to see more meteors than those at more northerly latitudes.

In a dark sky – when the moon is down – especially at more southerly latitudes, the Eta Aquariids can produce up to 20 to 40 meteors per hour. From mid-northern latitudes, you might only see about 10 meteors per hour.

Why more Eta Aquariid meteors in the Southern Hemisphere?

In general, the best time to watch these fast and often bright meteors is in the hour or two before the onset of morning twilight. Don’t know when twilight begins in your part of the world? Visit Sunrise Sunset Calendars and remember to check the astronomical twilight box.

Want to know the time of moonrise in your area? Visit Sunrise Sunset Calendars, and check the moonrise and moonset box, to find out when the moon sets in your sky.

Give yourself at least an hour of viewing time for watching any meteor shower. Meteors tend to come in spurts that are interspersed by lulls. Also, it can take as long as 20 minutes for your eyes to adapt to the dark.

You need no special equipment to watch a meteor shower, but a little luck always helps. Find a dark, open sky away from artificial lights, and sprawl out on a reclining lawn chair. Meteor watching is a lot like fishing. Sometimes you catch a good number of them, and sometimes you don’t.

Chart: lines marking constellation Aquarius with radial arrows near middle of it.
Radiant point of Eta Aquariid meteor shower. It’s in the constellation Aquarius, in the southeast before dawn on May mornings, as seen from mid-northern latitudes.
Sky chart of constellation Aquarius with Water Jar marked in red.
A Y-shaped asterism called the Water Jar marks the radiant of the Eta Aquariid meteor shower. It’s noticeable, if your sky is dark.
Thin vertical bright line in dark blue sky, with a tall Saguaro cactus in the foreground.
You can see the Eta Aquariid’s radiant point – the Water Jar asterism in the constellation Aquarius, visible as a noticeable pattern of 4 stars in the top left of this photo – in this photo by Eliot Herman in Tucson, Arizona, on May 4, 2020. Thank you, Eliot!

Radiant point of the Eta Aquariid shower. If you trace the paths of the Eta Aquariid meteors backward, they all seem to radiate from a certain point in front of the constellation Aquarius the Water Bearer. This point on the sky’s dome is called the radiant of the meteor shower, which nearly aligns with the faint star Eta Aquarii. Hence, this meteor shower is named in honor of this star.

Eta Aquarii is one of the four stars making up the Y-shaped Water Jar asterism in the northern part of Aquarius. If you can find the Water Jar in the constellation Aquarius, you’ve as good as located the radiant point for the Eta Aquariid meteors. The alignment of the radiant and the star is of course coincidental. Eta Aquarii is some 170 light-years away – trillions upon trillions of miles away – while the Eta Aquariid meteors burn up about 60 miles (100 km) above Earth’s surface.

Meteor shower radiants are sometimes misunderstood by casual meteor-watchers. You don’t need to know where they are to watch a meteor shower. That’s because the meteors fly every which way across the sky, in front of numerous constellations. However, the higher a shower’s radiant appears in your sky, the more meteors you’re likely to see. For the Eta Aquariids, the radiant soars highest in the nighttime sky just before dawn. That’s why you can expect to see the most meteors in the wee morning hours.

You can see some Eta Aquariid meteors in late evening, before the radiant rises into your sky. In fact, late evening is the best time to see earthgrazers, meteors that make exceptionally long streaks across your sky. As the radiant rises higher – that is, as the hours of the night tick away to dawn – you’ll see shorter meteors, but more meteors.

Comet, bright head and cone-shaped tail against star field.
Halley’s comet, the parent of the May Eta Aquariid and October Orionid meteor showers. Dust from this comet will streak the nighttime as Eta Aquariid meteors on the mornings of May 5 and 6. Image via NASA Blueshift.

Halley’s comet is the source of the Eta Aquariid meteor shower. Every year, our planet Earth crosses the orbital path of Halley’s comet in late April and May, so bits and pieces from this comet light up the nighttime as Eta Aquariid meteors. This shower is said to be active from April 19 to May 20, although Earth plows most deeply into this stream of comet debris around May 5 or 6.

The comet dust smashes into Earth’s upper atmosphere at nearly 150,000 miles per hour (240,000 km per hour). Roughly half of these swift-moving meteors leave persistent trains – ionized gas trails that glow for a few seconds after the meteor has passed.

Our planet also crosses the orbital path of Halley’s comet at the other end of the year, giving rise to the Orionid meteor shower, which is usually at its best in the predawn hours on or near October 21.

Bottom line: What’s a good meteor shower for the Southern Hemisphere? It’s usually the Eta Aquariid shower. We in the Northern Hemisphere can see this shower, too, peaking on the morning of May 5, 2021. If you’re clouded out that morning, try May 6.

EarthSky’s meteor shower guide for 2021

May 4, 2021
Astronomy Essentials

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Bruce McClure

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