Stargazers will have the chance to spot the most impressive comet of the year over the next few weeks.
Comet A3, also known as Tsuchinshan-ATLAS, has been hailed by excited astronomers as the “comet of the century” amid expectations of how bright and visible it could be.
People in the Southern Hemisphere have already spotted the comet, but starting Saturday, if it comes within about 70 million miles of Earth, it will also be visible in the Northern Hemisphere.
So what is Comet A3 and how likely are we to get a good look at it?
When was this discovered?
The comet was discovered independently in January 2023 by two observatories – China's Tsuchinshan Observatory (Purple Mountain) and South Africa's ATLAS (Asteroid Terrestrial-impact Last Alert System) – and was named after them.
It visits the inner solar system about every 80,000 years, so it was visible from Earth the entire time Neanderthals walked the planet.
Where is this from?
It comes from a place called the Oort Cloud, which he said Dr Robert Massey of the Royal Astronomical Society (RAS)this is an “incredibly large” distance from Earth, much greater than the planets and asteroids we usually see.
The Oort Cloud is a giant spherical shell surrounding our Solar System that contains billions of objects, including comets.
Two views of Comet A3 from the Atacama region in Chile. Photo: AP/Patrick Ditz
When will it be possible to see it?
It was visible between September 27 and October 2, but there is a greater chance of seeing it between October 12 and 30.
NASA astronomer Bill Cooke he said the best approach was to “choose a dark vantage point just after dark and look southwest.”
“And enjoy the view,” he added, because in early November the comets will disappear again for the next 800 centuries.
Called the “comet of the century”, seen from Gran Canaria. Photo: Reuters/Borja Suarez
How clear could it be?
Dr Massey warned that the “comet of the century” could turn out to be just a nickname.
He said it would be a “nice comet” but likely less visible than NEOWISE in 2020 or Hale-Bopp in the late 1990s – and many stargazers remember the latter as a “really dazzling object.”
Cooke said comets are often difficult to predict because they are extended objects.
He said if there is a lot of forward scattering, causing sunlight to reflect more intensely off all the gas and debris in the comet's tail and coma, it could make them easier for observers to see.
Comet A3 as seen from the International Space Station
Can I have his photo?
Dr. Massey suggests using a “good DSLR (digital single-lens reflex camera)” and trying a set of exposures, as many astrophotographers do.
If you have a good cellphone camera and a small telescope, he said, you can “hold your cellphone up to the telescope's eyepiece and try to take a picture that way.”
Dr Massey said this method “works well for comets like NEOWISE and may work well with this one, depending on its brightness.”
“And if it's really easy to detect, maybe you can pick up your cell phone, lean on something and just point and shoot,” he added.
What will happen to him later?
Pan Cooke said Comet A3 is not expected to pass too close to planets, but eventually “it could be ejected from our solar system – like a stone from a slingshot – due to the gravitational influence of other worlds and its weak bond with the Sun.”
But he said he “learned a long time ago not to take chances on comets. We'll have to wait and see.”
