April 21, 2024

The spectacular aurora australis can be visible from Victoria to Western Australia this week after a violent geomagnetic storm erupted on the sun’s surface.

The glittering spectacle comes on the same night as a penumbral lunar eclipse, which will be visible across the country.

The Bureau of Meteorology’s space weather forecast center issued an aurora warning Monday morning that said the storm was ongoing and the southern lights could be visible.

The storms are caused by coronal mass ejections, when clouds of plasma erupt from the sun’s outer atmosphere. Particles stream toward Earth, creating the spectacular display as they hit Earth’s magnetic field.

The storm peaked at 6 on the Kaus index (on a scale of one to eight that measures geomagnetic activity), meaning auroras may be visible across Tasmaniaalong Victoria’s coastline and even on Western Australia’s south-west coast.

They are more commonly seen from Antarctica, but the worse the storm, the further north they appear.

Severe storms can disrupt power grids and the satellites that provide navigation, surveillance and communications services. They can also pose a radiation risk to astronauts and people in high-flying aircraft.

The Board advises people hoping to see the aurora australis to find somewhere dark, such as a beach or a hill with an unobstructed view to the south. The best viewing time is between 10pm and 2am.

Last year there were reports of glittering night skies from Busselton in WA, to Ballarat and Canberra.

Macquarie University astronomer Dr Stuart Ryder said the 11-year solar cycle was probably nearing its peak.

“It goes from a relatively benign, calm state with very few sunspots on the surface to a very active phase about five or six years later, with a maximum number of sunspots,” he said.

“They are much more likely to release large flaring energy, enormous amounts of charged particles that radiate from the sun… their characteristic colors are green or red, but people report blue, yellow, even purple.

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“The more powerful the flare and the more it sticks out, the greater the chance that people who live more towards the equator will be able to see them.”

Tonight and tomorrow night would be the best time, he said.

Meanwhile, at around 7pm tonight in Sydney and 7.30pm in Melbourne, the Earth’s shadow, or penumbra, will dim the moon.

It will be visible in places including North and South America, as well as parts of Asia and Africa. In Australia, the details for people hoping to catch it are published on timeanddate.com.

Ryder said the eclipse will be half over by the time the moon clears the horizon. “Even when that happens, the moon will not pass through the deepest part of Earth’s shadow,” he said. “It will be a full moon, and the upper part may look a little darker because it is deeper in the Earth’s shadow.

“Then the moon will move out of the shadow it’s in and be restored to full brightness… which unfortunately could ruin people’s chances of seeing the aurora.”

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