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Watch for Delta Aquarid meteors

The Delta Aquarid shower is long and rambling and overlaps with the Perseids. Since the moon will be bright during this year’s Perseid peak, this weekend is a great time to watch meteors.

David S. Brown caught this meteor on July 30, 2014, in southwest Wyoming.

David S. Brown caught this meteor on July 30, 2014, in southwest Wyoming.

The Delta Aquarid meteor shower rambles along steadily from about July 12 to August 23 each year, and it peaks in late July. In 2017, the August 7 full moon means the annual famous Perseid meteor shower will be drowned in bright moonlight. We’re recommending you watch meteors this year beginning in late July, and especially beginning this weekend! In late July, the moon is setting during the evening hours. The skies are moon-free between midnight and dawn, the peak hours of the night for meteor-watching. Click here, and check the moonrise and moonset box, to find out when the moon sets in your sky. Will you see a magnificent meteor display? Probably not, but you will see some meteors! This shower overlaps with the Perseids, so the meteors will be flying from two different directions in the sky. Lots of fun to watch! Follow the links below to learn more.

When and how should I watch the Delta Aquariid meteor shower?

How can I tell Perseid meteors from Delta Aquariid meteors?

Delta Aquariid meteors may come from Comet 96P Machholz.

John Hlynialukk caught this meteor on November 14, 2015 from the Bluewater Outdoor Education Centre near Wiarton, Ontario.  He wrote:

Dark skies are best for watching meteor showers. Photo by John Hlynialukk at the Bluewater Outdoor Education Centre near Wiarton, Ontario.

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. In 2017, the rather wide waxing crescent moon won’t intrude on the peak dates around late July. The moon will set before midnight, and – as all true meteor-watchers know – the best meteor-viewing hours are after midnight and before dawn. For the Delta Aquarids, the best time is centered around 2 a.m. (3 a.m. Daylight Saving Time) for all time zones around the world.

The Delta Aquarid meteors tend to appear 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 Aquarid shower.

The Delta Aquarid shower is said to favor the Southern Hemisphere. But viewers at mid-northern latitudes will see plenty of these meteors. 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, under a dark country sky.

About five to ten percent of the Delta Aquarid meteors leave persistent meteor 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 60 miles (100 km) above the Earth’s surface. Watch for their lingering trains!

Everything you need to know: Perseid meteor shower

Radiant point of Delta Aquarid meteor shower

Radiant point for Delta Aquarid shower is near star Skat, or Delta Aquarii. This star is near in the sky to a much brighter star, Fomalhaut, which can be found roughly on a line drawn southward through the stars on the west side of the Great Square.

How can I tell Perseid meteors from Delta Aquariid meteors? This is where the concept of a radiant point comes in handy. You never have to locate a shower’s radiant point to enjoy the meteors. But … if you trace all the Delta Aquariid meteors backward, they appear to radiate from a certain point in front of the constellation Aquarius the Water Bearer. As viewed from the Northern Hemisphere, this point – the Delta Aquariids’ radiant point – arcs across the southern sky. It’s overhead for Southern Hemisphere viewers (which is why the shower is best from that part of the world).

The radiant point of the Delta Aquariid shower nearly aligns with the star Skat (Delta Aquarii). The meteor shower is named in honor of this star.

Meanwhile, the Perseids radiate from the constellation Perseus, in the northeast to high in the north between midnight and dawn, as seen from the Northern Hemisphere. So if you’re in this hemisphere, and you’re out watching for meteors, 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.

If you’re in the Southern Hemisphere, your Delta Aquarids will be radiating from nearly overhead. Your Perseids will be shooting up from somewhere along your northern horizon.

In a particularly rich year for meteors, if you have a dark sky, you might even see Perseid meteors cross paths with Delta Aquariid meteors! It can be an awesome display.

Comet 96P Machholz, the possible parent of the Delta Aquarid meteor shower, was discoverd on May 12, 1986, by Donald Machholz. Photo: Wikimedia Commons

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 90,000 miles (150,000 km) 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 Aquarids’ 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 July 14, 2012 and will next come to perihelion on October 27, 2017.

Bottom line: The Delta Aquarid meteor shower rambles along pretty steadily in late July and August, coinciding with the Perseids. From any time zone, the best viewing window is centered on roughly 2-3 a.m. Find an open sky away from artificial lights, lie down on a reclining lawn chair and look upward. In 2017, the prospects for watching the Delta Aquarids in late July are very good, with no moonlight to ruin the predawn show.

Everything you need to know: Perseid meteor shower

Bruce McClure