Skywatchers were treated to a celestial delight on Wednesday evening, with a severe solar storm making it possible to view the southern lights across large parts of Australia and New Zealand.
A severe solar storm had paved the way for the spectacular display of aurora australis, particularly in Victoria, and as far north as the Blue Mountains where there were reports of the lights over the Three Sisters near Katoomba.
Displays of the northern lights, also known as aurora borealis, were visible in the northern hemisphere overnight on Tuesday.
“Given the strength of this storm, there’s a chance people farther north than typically expected in the southern hemisphere might be able to see it,” astronomer Dr Laura Driessen, from the Sydney Institute for Astronomy, said on Wednesday, adding it could be visible to people in Sydney and Perth.
“Tasmania and New Zealand should get a decent view,” she said.
Wednesday night was “the best chance for people to go outside and try catch a glimpse of the aurora,” Dr Sara Webb, an astrophysicist at Swinburne University, said. “It looks like it’s going to be very high up the southern coast of Australia, so visible from parts of Victoria and New South Wales.”
What causes the aurora australis?
According to the BoM on Wednesday, “G4 geomagnetic storm conditions are currently being observed.” The maximum on the geomagnetic storm scale is a G5.
“It is quite an intense geomagnetic storm, one of the largest that we’ve seen in recent years,” Webb said .
The sun has an activity cycle of about 11 years, which peaked last October. Around that solar maximum, “we get more sunspots, which are areas where there’s magnetic activity,” Webb said.
“We also see things like coronal mass ejections … we get some of the magnetic field lines from the sun interacting with each other, essentially breaking, and releasing energy and plasma towards us.”
Two “massive” coronal mass ejections have been observed since 9 November, which were expected to hit Earth on Wednesday afternoon, Webb said. These bursts of high-energy plasma disturb the Earth’s magnetic field, known as the magnetosphere.
Auroras, or aurorae, result from that disturbance.
“All of this in combination adds energy to some particles in our atmosphere,” Driessen said. “A lot of the colours we see are from oxygen and neon getting excited – as those particles calm back down again they emit these beautiful coloured lights.”
