After the night sky in Australia was illuminated by a trio of meteor showers – the Piscis Austrinids, the Southern Delta Aquariids and the Alpha Capricornids late last month, stargazers will be able to see the 2022 Perseid meteor shower peak on 13 August.
The Perseids are considered by Nasa to be “the best meteor shower of the year”. This year, however, they coincide with a full moon on 12 August, resulting in less than ideal viewing conditions. Due to the brightness of the Perseids, though, some meteors should still be visible in a sky illuminated by moonlight.
What are meteor showers?
Meteor showers occur when cosmic debris enters the Earth’s atmosphere. The source of this debris is often from comets, which have long orbits around the sun.
“Like my cat, comets shed bits,” says Professor Orsola De Marco of Macquarie University. “These bits remain pretty much in orbit – so imagine a very elongated orbit that’s full of little bits.”
When the Earth crosses the path of a comet’s orbit, it encounters this debris. “It’s like when you are driving your car through a cloud of insects – you get them all in your windshield,” De Marco said.
The debris burns up as it enters Earth’s atmosphere, resulting in dazzling displays across the sky.
The Perseids are associated with the comet Swift–Tuttle. The Southern Delta Aquariids come from the comet 96P/Machholz, while the parent body of the Alpha Capricornids is the comet 169P/NEAT. Astronomers have not yet found where the Piscis Austrinids originate from.
A meteor shower is named after the nearest constellation to the radiant, the point in the sky which the shower appears to come from. The radiant of the Southern Delta Aquariids, for example, is close to the star Delta Aquarii, in the constellation Aquarius.
When and where is the best time to view the meteor showers?
Perseid meteor shower: peaks 13 August
While the meteor showers are visible from everywhere on Earth, the Perseids are best viewed from the northern hemisphere.
The dazzling Perseids meteor shower is expected to peak on 13 August. At its peak, there can be more than 100 meteors an hour.
The radiant of this meteor shower is very close to the horizon, De Marco says. “You’re going to see [meteors] going upwards from the north horizon. They’re going to look like they are rising as opposed to falling.”
In Australia, the best viewing will be towards the north at 5am on 13 August. However, the bright full moonlight may obscure many of the meteors from sight.
Piscis Austrinids, Southern Delta Aquariids and Alpha Capricornids
New Zealand astronomer and director of Otago Museum, Ian Griffin, says the Piscis Austrinids, Southern Delta Aquariids and Alpha Capricornids showers are easily visible with the naked eye. “You don’t need a telescope to see them, you just need a deck chair and your eyeball,” he says. The three meteor showers are active until mid-August.
The Southern Delta Aquariids peaked on 30 July . This shower has the quickest meteors of the three. At their peak, they are visible around 11pm, to the east-northeast and 45 degrees upwards from the horizon, De Marco says. New Zealand will see the shower around 1am.
The Alpha Capricornids are “relatively bright and will have some fireballs,” De Marco says. Fireballs are very bright meteors – at least as bright as Venus in the morning or evening sky. At its peak, at about 11pm the shower can be visible to the north-northeast, about 65 degrees up from the horizon. New Zealanders can see it around 1am.
The Piscis Austrinids peaked on 28 July. If you’re on the east coast of Australia, it rises around 8pm to the south-east, travelling closer to due east by 11pm, De Marco says. “Look towards the east, about 45 degrees up – about halfway between the horizon and above your head.”
In New Zealand, the best viewing time will be after 10pm.
For people who want to plan their viewing experience in more detail, the open-source software Stellarium can model the night sky in 3D.