If a dazzlingly bright star suddenly bursts into view just to the right of the Southern Cross, “do not be afraid” says Professor Brian Schmidt of the ANU.
“I think people should go out and enjoy the view,” he says.
Alternatively you might want to bolt for the cellar and prematurely drink the Grange while waiting for the last birds to fall dead from the skies after a lethal burst of gamma rays. It’s your choice.
Schmidt was commenting on US reports identifying the obscure star Eta Carinae, which is near the Cross, as the one “most likely” to turn supernova in our corner of the universe any time between tonight and the next few thousand years.
An American team made this prediction as a throwaway line after announcing that supernova SN 2006gy that has lit up a galaxy far, far away from our own since last September was the most monstrous, unstable, powerful and rarest of its type ever studied “live”.
And that the closest candidate to repeat this performance in our neighbourhood was a mere 7.5-10 thousand light years away.
Schmidt says “The physics of supernova explosions tells us it takes two or three months for the gamma rays to escape from the blast, and they halve in intensity every six days.”
There would be no need to evacuate the International Space Station, ground airlines, or order the panic stricken masses to take cover.
“It will be a fantastic sight, and it will inevitably happen one day because Eta Carinae is a massively unstable object with over 100 times as much matter as the sun.”
So far so good. Schmidt was joint winner of the prestigious Shaw Prize for Astronomy last year for his breakthrough discoveries about dark energy, the rate of expansion of the universe, and supernovas.
But…”I’m not so sure about Sirius,” he says. Gulp! Sirius is a large white star, rather larger and faster burning than our sun, and it is a mere 8.6 light years away.
It has a nearby companion sun, Sirius B, which is a dense, hot, white dwarf, an incredibly compact star about the size of earth that orbits Sirius A close enough to compress anything that erupts from the main star onto its own surface, triggering a cataclysmic explosion and burst of radiation.
“Most of my colleagues say Sirius will never explode,” Schmidt says.
“I just don’t think we have enough data to be sure about that, and if or when Sirius A ever throws off a lot of material at once and it piles onto Sirius B there will be consequences.”
Such as any observing astronomers uttering last words, like “Oh bother”, not that they will ever make the news, since there won’t be any.
Schmidt says more exciting discoveries in the parts of the universe very, very near to us can be expected in the next five years.
He leads the ANU SkyMapper project, which will detect and identify the characteristics of everything from asteroids and quasi planets in the outer solar system, to a whole range of star types and enigmatic objects in our own galaxy with 100 times better resolution than ever before.
And remember, if Eta Carinae goes “off” in our lifetimes, we will live for a few weeks on a planet with two suns, the other visible for every hour of the day from southern skies until it fades yet expands into an incredible shell of glowing debris that will be a stunning night time object for hundreds of years thereafter.