Nishimura, a green comet that was only discovered in August, will be visible in Australian skies within days – hopefully.
Comets are often called “dirty snowballs” because they are made of rock, dirt, ice and gas – and it is Nishimura’s “gassy” nature that makes it appear green in images.
Since the amateur Japanese astronomer Hideo Nishimura spotted it (using a standard digital camera), eager comet-watchers have tracked its progress through the solar system.
The comet, officially named C/2023 P1, was hit by a solar wind earlier this month, “briefly blowing it to smithereens”.
“An intriguing new celestial object known as Comet Nishimura is enduring a bumpy ride through the inner solar system despite having its tail torn off by an outburst from the sun,” Scientific American reported.
The tail regrew, but Nishimura could face more solar storms.
Astronomer Donna Burton – the first Australian woman to discover a comet – said the best way to spot Nishimura would be at sunrise and sunset, and from somewhere with no light pollution. And she warned about disappointment because of the unpredictability of comets.
Burton, a PhD candidate at the University of Southern Queensland and an astronomer at Coonabarabran’s Milroy Observatory, said: “It’s very low on our horizons … even the northern hemisphere photos you’re seeing are taken by guys with really amazing cameras and gear.
“Because comets are so unpredictable you just don’t know if they’re going to be sensational, incredible … or fizzers. But it may surprise us.”
While it is theoretically visible from next week, the best view is likely to be later in October, and it will be more easily spotted with a telescope and a camera, Burton said.
“You’ll never see it from the city. You’ll have to get away from light pollution, find a dark sky area where there’s no moon,” she said.
And there’s another chance for disappointment. While comets can be green because of their chemical properties, even if the colour shows up in pictures the colour might not be seen by the human eye.
Burton said her own comet discoveries (she has found two) were a “bit of an anticlimax”.
She was working at Siding Spring Observatory’s Near Earth Object Survey Project in New South Wales.
“They’d discovered 80, 85 comets. That was their job, I just came in for a year,” she said. “I was super excited, nobody else was. My husband was, and the boss had to be.”
According to Nasa, Nishimura’s tails are growing as it gets nearer to the sun and it is “already near naked eye brightness as it now moves inside the Earth’s orbit”.
It is close to Earth’s orbit this week, but will be nearest the sun next week. Nasa said its brightness will intensify as it gets closer to the sun, but that the sun’s glare could also obscure it, and once it is inside Mercury’s orbit it will be so close to the sun that the nucleus may break up.
If you miss Nishimura this time, and it doesn’t get blown up by the sun, it will be back in 435 or so years.
