Astronomy Essentials

Delta Aquariid meteor shower: All you need to know in 2023

Every year, 2 meteor showers – the famous Perseids and the lesser known Delta Aquariids – converge in late summer. The Delta Aquariids always peak in late July. And the Perseid meteor shower peaks around August 12 and 13.

When to watch: Watch late July through early August, mid-evening to dawn. There’s a predicted* peak for July 30, 2023, at 18 UTC. But this shower doesn’t have a noticeable peak. It rambles along steadily from late July through early August, joining forces with the August Perseids. In fact, Delta Aquariid meteors fly for weeks!
Nearest moon phase: In 2023, the full moon falls at 18:31 UTC on August 1. Take advantage of the moon-free mornings in late July for watching the Delta Aquariids (and early Perseids).
Radiant: Rises in mid-evening, highest around 2 a.m. your local time and low in the sky by dawn. See chart below.
Duration of shower: July 18 to August 21.
Expected meteors at peak, under ideal conditions: The Delta Aquariids’ maximum hourly rate can reach 15 to 20 meteors in a dark sky with no moon. You’ll typically see plenty of Delta Aquariids mixed in with the Perseids, if you’re watching in early August.
Note: Like May’s Eta Aquariids, July’s Delta Aquariids favors the Southern Hemisphere. Skywatchers at high northern latitudes tend to discount it. But the shower can be excellent from latitudes like those in the southern U.S. Delta Aquariid meteors tend to be fainter than Perseid meteors. So a moon-free dark sky is essential. About 5% to 10% of the Delta Aquariid meteors leave persistent trains, glowing ionized gas trails that last a second or two after the meteor has passed.

Report a fireball (very bright meteor) to the American Meteor Society: it’s fun and easy!

Delta Aquariid radiant point

Meteor shower chart: Radial arrows below Great Square of Pegasus and above Fomalhaut.
The radiant point for the Delta Aquariids is near the faint star Skat, or Delta Aquarii. It rises in mid-evening, is highest around 2 a.m. and low in the sky by dawn. Use the bright, nearby star Fomalhaut to guide you to the Delta Aquariid radiant point. Find Fomalhaut by drawing a line southward through the stars on the west side of the Great Square of Pegasus. This chart shows a wide area, from overhead to southward, as seen from the Northern Hemisphere. From the Southern Hemisphere, the radiant is closer to overhead.

The Delta Aquariid’s parent comet

From the late, great Don Machholz,(1952-2022), who discovered 12 comets…

The Delta Aquariid meteor shower’s parent comet comes from the 96P/Machholz Complex.

The 96P/Machholz Complex is a collection of eight meteor showers, including the Delta Aquariids, plus two comet groups (Marsden and Kracht), and at least one asteroid (2003 EH1). These meteors showers, and these comets, appear to share a common origin (although they’ve now diverged slightly in their orbits around the sun).

They are all related to the comet known as 96P/Machholz, which I discovered on May 12, 1986, from Loma Prieta Mountain in California.

At discovery, the comet was magnitude 10 and two degrees south of the Andromeda galaxy. I was using my 6-inch homemade binoculars for this find. Read the story of the discovery.

As a matter of fact, scientists had suspected the existence of the 96P/Machholz Complex in 2003. Finally, they fully described it in 2005, after conducting more studies.

Comet 96P/Machholz orbits the sun every 5.3 years and gets eight times closer to the sun than we are. That is, its perihelion distance is 0.12 astronomical units (AU). One AU is the distance between the Earth and the sun. So this comet comes well inside the orbit of Mercury. Over the course of 4,000 years, the comet’s orbit changes in shape and tilt, so that it leaves particles throughout the inner solar system. It gets around!

A recent study suggests that the material causing the Delta Aquariid meteor shower left the comet’s nucleus about 20,000 years ago. It’s old dust streaking across our skies.

Starry background, largish bright dot with 2 fuzzy tails.
EarthSky’s Don Machholz discovered comet 96P Machholz, the parent of the Delta Aquariid meteor shower, on May 12, 1986. This 2007 image is from the HI-2 camera of STEREO-A spacecraft. Image via Wikimedia Commons.

Perseid? Or Delta Aquariid?

Perseid and Delta Aquariid meteors fly in our skies at the same time of year. How can you tell them apart? This is where the concept of a radiant point comes in handy. If you trace all the Delta Aquariid meteors backward, they appear to radiate from a certain point in front of the constellation Aquarius, which, as viewed from the Northern Hemisphere, arcs across the southern sky.

Meanwhile, the Perseids radiate from the constellation Perseus, in the northeast to high in the north between midnight and dawn as seen in Northern Hemisphere skies.

So – assuming you’re in the Northern Hemisphere, and watching around midnight or after – if you’re watching the Perseids and you see meteors coming from the northeast or north … they are Perseids. If you see them coming from the south … they are Delta Aquariids. In a particularly rich year for meteors, if you have a dark sky, you might even see them cross paths!

Consequently, it can be an awesome display.

Delta Aquariid meteor shower photos from the EarthSky community

Submit your night sky photos to EarthSky here

Meteors falling in a dark sky.
View at EarthSky Community Photos. | Bass Seckin in Bursa, Turkey captured these meteors on July 29, 2020 and wrote: “Bursa is 3 million populated city located in northwestern Turkey. It’s almost impossible to see meteors there … I went 100 kilometers (60 miles) out eastward for excluding light pollution. Interestingly I had seen only one or two meteors with unaided eye, but when checked frames I have seen that there were 4 to 6 meteors on single frame. The reddish spot at the center of the image is Mars, and Delta Aquariids meteors’ traces are from upper right corner toward bottom.” Thank you, Bass!
Long bright diagonal line streaking among clouds.
Kelly Dreller caught this meteor in late July 2016, in Lake Havasu City, Arizona.

Bottom line: The nominal peak of the Delta Aquariid meteor shower is late July. But the shower rambles along steadily in late July and August, intermingling with the Perseids. In 2023, watch in late July to avoid moonlight.

*Predicted peak times and dates for 2023 meteor showers are from the American Meteor Society. Note that meteor shower peak times can vary.

Everything you need to know: Perseid meteor shower

Meteor showers: Tips for watching the show

EarthSky’s meteor shower guide for 2023

Posted 
July 25, 2023
 in 
Astronomy Essentials

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