Astronomy enthusiasts will witness a “double” meteor shower as both the Alpha Capricornids and Southern Delta Aquariids peak next week. Nicholas Moskovitz, a planetary astronomer at the Lowell Observatory in Arizona, USA, stated: “This is an incredible coincidence.”
When Earth’s Orbit Intersects with Two Comets
Meteor showers occur when Earth’s orbit intersects with the path of a comet. The rocky debris left by the comet burns up upon entering Earth’s atmosphere. In this month’s double meteor shower, Earth will pass through the orbit of comet 96P/Machholz—causing the Southern Delta Aquariids to peak on July 29-30—and comet 169P/NEAT, which produces the Alpha Capricornids peaking on July 30-31.
A Perseid meteor streaks across the sky over Spruce Knob, West Virginia, USA. (Photo: NASA/Bill Ingalls)
Astronomer Moskovitz noted that two meteor showers peaking within 24 hours is unusual. He pointed out that there are more than 900 meteor showers throughout the year, meaning that on average, two to three meteor showers occur each night. However, not all are “major” meteor showers like the Perseids or Geminids, which feature over 100 bright meteors per hour. Most meteor showers are small, and astronomers have only recently begun to systematically study and measure these showers thanks to newly developed equipment.
Meteor showers occur regularly due to their predictable orbits around the Sun. The small annual variations in their intensity are determined by when the comet releases debris and how long the debris drifts in space. Moskovitz, who leads the Lowell Observatory Cameras for All-Sky Meteor Surveillance (LO-CAMS), a network of cameras monitoring meteors, stated that predicting meteor showers is crucial for the safety of spacecraft and humans traveling in space.
At its peak, the Southern Delta Aquariids will show observers about 20 to 25 meteors per hour (whereas a typical background meteor shower has around five meteors per hour). The Southern Delta Aquariids are expected to appear “rather faint.”
Astronomer Moskovitz suggested: “You should find a dark location, away from lights and traffic, avoid mobile phones, and let your eyes adjust to the darkness so you might have a chance to see some of those faint objects.“
Brilliant Fireballs
The Alpha Capricornids are much less frequent, but they are often associated with “bright fireballs with larger meteoroids flying in and burning bright, becoming more spectacular.” These remarkable bright meteors are made up of particles the size of marbles, while dimmer meteors are usually the size of grains.
The double meteor shower will be best observed in the Southern Hemisphere. Those in the Northern Hemisphere can also see the meteor shower if they have a clear view of the southern horizon. Both meteor showers will continue until mid-August.
Both meteor showers can be best observed with the naked eye. However, to make the most of other sky-watching events this year, you might need a new pair of binoculars or a good backyard telescope.
