This month sees a very special visitor to the skies over Earth: a comet that only passes by once every 80,000 years. The last time this comet passed Earth, Neanderthals populated the planet, hunting with stone tools. Now, Comet Tsuchinshan-ATLAS has been photographed on its journey around the sun by humans living in orbit in the International Space Station.
The comet made its closest pass of the sun on September 27, but is even more visible in the sky now as it passes by Earth. ISS astronauts have tracked the comet as it approaches, and the next few days should offer the best chance for those of us here on the surface to see this remarkable sight streaking through the sky.
“Though the comet is very old, it was just discovered in 2023, when it approached the inner solar system on its highly elliptical orbit for the first time in documented human history,” NASA wrote in an update. “Beginning in mid-October 2024, Comet C/2023 A3 (Tsuchinshan-ATLAS) will become visible low in the west following sunset. If the comet’s tail is well-illuminated by sunlight, it could be visible to the unaided eye. Oct. 14-24 is the best time to observe, using binoculars or a small telescope.”
As well as the image above, taken by NASA astronaut Matthew Dominick, some NASA missions have also caught glimpses of the comet. A striking image was taken as the comet passed the NASA/European Space Agency’s Solar and Heliospheric Observatory (SOHO) spacecraft, which orbits the sun and saw this blazing view of the comet on October 10.
Comets have their distinctive tails because of their composition. Unlike asteroids, which are made of rock, comets are made of a mixture of rock and ice. As they get close to the sun, the comet warms up and this ice sublimates into gas, creating the stunning tail.
However, this effect also makes comets’ brightness and lifespan hard to predict as they can break up depending on how much ice material they hold and how quickly they disintegrate. There had been hopes that this comet would be a super-bright “comet of the century,” but this is still a relatively dim object in the sky. According to space.com, the comet may already be breaking up and may not survive for much longer. So if you’re hoping to get a glimpse of this ancient wonder, you better move fast.