Comet C/2024 G3 ATLAS as seen over Wrights Hill in Wellington on 21 January. Photo: Supplied / Antony Gomez
A once-in-a-lifetime comet has been spotted over New Zealand skies this week.
Comet C/2024 G3 (Atlas), which last visited the Sun about 180,000 years ago, is expected to continue to be visible for the next few nights for those with clear skies.
On its return visit, the influence of gravity as it travelled through the solar system curbed its trajectory, making it appear bigger, the Royal Astronomical Society of New Zealand (RASNZ) said.
But RASNZ comet section director John Drummond said the comet was going to be a "headless wonder" now, getting dimmer as the effects from passing near the Sun about a week ago set in.
"When you look at it, you'll just see the tail of the comet in the sky, but you won't see a definite ... fairly bright ball with the head, with the dust and gas coming away.
"The head is basically shattered because what happens is a comet is really just a loose pile of rubble and frozen gas and dust and so it's not a solid rock, it's more of a conglomeration of material, and it's come close to the sun ... and because of that, the sun's influence with the heat and the pressure from the sun, the gravity basically shattered it."
- Did you snap any pictures of Comet C/2024 G3 (Atlas) over New Zealand? Send them our way on iwitness@rnz.co.nz
Comet C/2024 G3 ATLAS as seen on 20 January in Wellington. Photo: Supplied / Antony Gomez
While it had been expected it would be seen again after 600,000 years, that hope had been dashed, he said.
"What will happen is it will just carry on disintegrating and then we will be able to see the tail in the sky ... for the next few nights at least, probably with the naked eye, better with binoculars, and you'll see it as a streak in the sky and then over the next week, it will get fainter and fainter."
It was also the best comet expected to be seen by the naked eye this year, Drummond said.
"But you never know, a comet can get discovered and late in the show and then suddenly appear a lot brighter."
Drummond said witnessing the comet go over Gisborne's skies on Monday was a neat experience to share with his family.
Comet C/2024 G3 ATLAS from 28 January about 10pm, taken from Wright's Hill by Wellington Astronomical Society member Chris Monigatti. Photo: Supplied / Chris Monigatti
He recommends going to a dark location, like Auckland's Piha or Bethells Beach, if you want to spot it over the next few nights.
"You'll see Venus up in the sky ... what people do is they look to the left of Venus about one-and-a-half hand span at arm's length and then go down about ... a fifth down, you'll hopefully see the streak.
"So with comets what you do is you sort of look for that area, you sweep your binoculars left, right, up, down, up and as you move up the sky from the horizon - make sure the sun is below the horizon - and hopefully you'll see the comet. You do need a very low Western horizon and you do need to get away from that terrible thing called light pollution.
"The good thing is it's now at a place in its orbit where each night it gets higher and higher in the sky, further away from the sun. So because it gets higher in the sky, there's less atmosphere to look through and so it should be a little bit easier to see over the next few nights until it fades too much."
Comet C/2024 G3 (Atlas) as seen from Gisborne on 18 January, 2025. Photo: Supplied / John Drummond
Antony Gomez is a Wellington-based climate change scientist but has had an interest in astronomy since he was a child and with his expanding knowledge became involved with the astronomy community groups in the early 2000s. He is now the national co-ordinator of NZ IAU Astronomy Outreach.
"There was quite a good interest from people just driving up there [at Wrights Hill] and wanting to look at the comet themselves - a lot of them had no ties to astronomy and they just came along because they heard somewhere about the comet and we [had] telescopes there.
"I think we started to see the comet about quarter to 10, 10 o'clock.
"Once it got dark enough and your eyes were adjusted and there was no streetlights nearby, you can actually see it quite clearly in the sky ... You can see this kind of wispy line stretching out over the cloud."
Pictured is a SOHO (LASCO C3) image of Comet ATLAS that is a composite of several different color filters. Of the several tails visible, the central white tails are likely made of dust and just reflecting back sunlight. The red, blue, and green tails are likely ion tails with their colors dominated by light emitted by specific gases that were ejected from the comet and energized by the Sun. Photo: NASA, SOHO, Processing: Rolando Ligustri
Witnessing the long tail on the rare comet had been "quite spectacular", he said.
"You don't know what's gonna happen to it, whether it's gonna survive and come out and be a really nice comet, or whether it's just gonna be a fizzle, or who knows? That [unknown] of what it could be like kind of draws you out thinking 'I must go out and have a look at this'."
NASA astronaut Don Pettit shared a photo on X of the comet from the International Space Station on 11 January.
It is totally amazing to see a comet from orbit. Atlas C2024-G3 is paying us a visit. pic.twitter.com/6Npqa2Wksf
— Don Pettit (@astro_Pettit) January 11, 2025
