Evrim Yazgin
Cosmos science journalist
Comet C/2023 A3 (Tsuchinshan-Atlas) will be visible over Australian skies in the coming days.
The comet has already made international headlines for the incredible views it has produced over the northern hemisphere.
It became visible to the naked eye soon after it passed its perihelion (the point at which its orbit is closest to the Sun) on 27 September. At this point, the comet was 2.5 times closer to the Sun than Earth.
The comet was discovered on 9 January 2023 by researchers looking at data from the Purple Mountain Observatory in China. It was also independently spotted by the ATLAS survey in South Africa on 22 February 2023.
C/2023 A3 is about 3.2km across and hails from the Oort Cloud – a giant spherical shell of icy objects surrounding the solar system.
“The comet’s visit is a very special opportunity to take a glimpse through time and space, because this comet is a relic from the formation of our solar system 4.5 billion years ago,” says Michael Brown, an associate physicist in the School of Physics and Astronomy at Melbourne’s Monash University.
Physicists can use information about objects’ trajectories, speeds and mathematical modelling to plot their course through the solar system over large time periods.
When C/2023 A3 was last visible over Earth, mammoths, sabre-toothed cats and Neanderthals were all still around.
“The last time it visited the inner solar system, making it visible from Earth, was roughly 80,000 years ago,” says Brown.
“The comet is rapidly fading as it moves away from the Sun and it has been years since we have seen a similarly bright comet, so take the opportunity to spot this celestial visitor sooner rather than later.”
Brown says the comet’s nucleus is made up of rock, dust and ice. Its characteristic tails are produced when it is heated by the Sun, releasing gas and dust.
“For the best chance to get a look at this comet, you should keep an eye on the western horizon during the early evening.
“Free astronomy apps can help you find the comet, with the bright planet Venus being a useful point of reference. It will be possible to see the comet’s tails with the unaided eye, but a pair of binoculars or a small telescope can provide better views.”
