Bad weather could ruin Aurora Australias event

John Lewis, Otago Daily Times,
Lower South Island,
Publish Date
Wednesday, 15 May 2019, 5:49PM
Mt Erebus below with the Milky Way above the aurora australis. (Photo / Jonny Harrison)
Mt Erebus below with the Milky Way above the aurora australis. (Photo / Jonny Harrison)

If the clouds part for long enough tonight, people along the Otago and Southland coastline may be in for a spectacular Aurora Australis light show.

University of Otago Physics Department head Professor Craig Rodger said earlier this week, there were two coronal mass ejections (CME) on the Sun (each a day apart), which fired significant amounts of plasma towards Earth.

The first of the two ejections hit Earth's magnetic field on Tuesday night, creating spectacular auroras on Stewart Island, the ODT report.

It is expected to be visible again between 9pm tonight and 3am on Thursday.

However, MetService has issued a severe wind warning for Clutha and Southland, as well as the Canterbury High Country,  Stewart Island and Tararua Districts.

It says the disturbed westerly flow will move over the lower South island tonight through to Thursday morning.

MetService says gusts could damage trees and power lines - and driving motorbikes and high-sided vehicles could be dangerous.

Rodger said the major problem would be the weather, but still has tips for those who may hope to see it. 

"It's generally easiest to see the Aurora Australis when you're coastal, away from city lights, and you can look south, low on the horizon, and not be blocked by other land masses.

"There is certainly a possibility, that if it's a big enough event and the aurora gets high enough in the sky, you could see it from anywhere in Otago and Southland.''

He said the aurora should be able to be seen with the naked eye, but the colours were unlikely to be seen without a camera.

"The Sun may give us a stunning display and you'll be able to see colour, but I can't promise that. It's more common that it will be a marginal display where human beings will only be able to see it in black and white.

"It's obviously in colour, but it's not strong enough to trigger the colour receptors in our eyes.''

Prof Rodger expected the second ejection to arrive sometime early on Friday morning.

"There could be more action tomorrow night but because it is a bit further out, it is harder to predict its exact arrival time.

"We're asking Mother Nature to behave, which she's not very good at.

"But if she plays by the rules, we should have an auroral display on Thursday night and Friday morning.''


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