Late July 2019 – around July 28 – presents the nominal peak of the Delta Aquariid meteor shower, but this long and rambling shower is officially active from about July 12 to August 23 each year. The new moon in early August 2019 means lovely waning crescent moons in the optimum predawn hours in late July, and dark skies throughout most of the night all through the first week of August 2019. The best viewing hours are after midnight and before dawn, centered around 2 a.m. (3 a.m. daylight-saving time) for all time zones around the world. This shower overlaps with the more famous Perseid meteor shower, which in early August is rising to its peak (this year on the mornings of August 11, 12 and 13). Those who observe the Perseids are likely to see some Delta Aquarid meteors flying on the same nights. Follow the links below to learn more.
When and how should I watch the Delta Aquarid meteor shower? Does this shower have a peak? It does have a nominal peak in late July. This year, in 2019, the slender waning crescent moon doesn’t seriously intrude on this year’s production.
The shower favors the Southern Hemisphere, though is still visible from mid-northern latitudes. In years when the moon is out of the way, the broad maximum of this shower can be expected to produce 10 to 20 meteors per hour. Some Delta Aquarids will still be flying on the peak nights of the 2019 Perseid shower (August 11, 12 and 13).
In any case, the August Perseid shower should be your best bet for watching meteors in the summer of 2019, in spite of the waxing gibbous moon. Watch these meteors in the predawn hours after the moon sets. Click here for a sky almanac.
Best time to look for both the Perseids and the Delta Aquarids is between midnight and dawn.
How can I tell Perseid meteors from Delta Aquariid meteors? This is where the concept of a radiant point comes in handy. If you trace all the Delta Aquarid meteors backward, they appear to radiate from a certain point in front of the constellation Aquarius the Water Bearer, which, as viewed from the Northern Hemisphere, arcs across the southern sky. The radiant point of the shower nearly aligns with the star Skat (Delta Aquarii). The meteor shower is named in the honor of this star.
Meanwhile, the Perseids radiate from the constellation Perseus, in the northeast to high in the north between midnight and dawn. So if you are 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 Aquarids. In a particularly rich year for meteors, if you have a dark sky, you might even see them cross paths! It can be an awesome display.
The Delta Aquarid meteors may tend to be a bit fainter than the Perseids and meteors seen in other major showers. That makes a dark sky free of moonlight even more imperative for watching the annual Delta Aquariid shower. About five to ten percent of the Delta Aquariid meteors leave persistent trains – glowing ionized gas trails that last a second or two after the meteor has passed. The meteors burn up in the upper atmosphere about 100 kilometers (60 miles) above the Earth’s surface.
Rememeber, you never have to locate a shower’s radiant point to enjoy the meteors. However, it does help to have a dark night without moonlight. This year – in 2019 – the prospects for watching the Delta Aquarids in late July are very good, with little moonlight to ruin the show.
Delta Aquarid meteors may come from Comet 96P Machholz. Meteor showers happen when our planet Earth crosses the orbital path of a comet. When a comet nears the sun and warms up, it sheds bits and pieces that spread out into that comet’s orbital stream. This comet debris slams into the Earth’s upper atmosphere at about 150,000 kilometers (90,000 miles) per hour, vaporizing – burning up – as meteors or shooting stars.
The parent body of the Delta Aquarid meteor is not known with certainty. It was once thought to have originated from the breakup of what are now the Marsden and Kracht sungrazing comets. More recently, the Comet 96P Machholz has loomed as the primary candidate for being the Delta Aquariids’ parent body.
Donald Machholz discovered this comet in 1986. It’s a short-period comet whose orbit carries it around the sun once in a little over five years. At aphelion – its greatest distance from the sun – this comet goes out beyond the orbit of Jupiter. At perihelion – its closest point to the sun – Comet 96P Machholz swings well inside Mercury’s orbit. Comet 96P/Machholz last came to perihelion on October 27, 2017 and will next come to perihelion on January 31, 2023.
Bottom line: The Delta Aquariid meteor shower lacks a very definite peak. It rambles along pretty steadily in late July and August, coinciding with the Perseids. The nominal peak in 2019 is in late July, shortly before the new moon on August 1, 2019. From any time zone, the best viewing window on July 28 or 29 lasts for several hours, centered on roughly 2 a.m. (3 a.m. daylight-saving time). Find an open sky away from artificial lights, lie down on a reclining lawn chair and look upward.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.