Ellen Phiddian
Cosmos science journalist
A comet discovered just weeks ago by an amateur astronomer could soon be visible to the naked eye.
Comet C/2023 P1 Nishimura was found by Japanese astrophotographer Hideo Nishimura, on 11 August. Nishimura was taking long-exposure photographs of the sky, with a digital camera.
The comet may get bright enough to see unaided by early September – although at the peak of its brightness, it will be very close to the Sun, meaning it may be obscured by glare.
Because it’s so newly discovered, the exact trajectory and visibility of the comet is still uncertain, with estimates changing day by day based on new observations.
It is expected to be visible in the pre-dawn sky up until around 7 September, getting brighter each day, in the constellation of Cancer. But, as it gets closer to the Sun’s glare each day, by mid-September it will be difficult to see.
Observers in the Northern Hemisphere will get the best view, and a pair of binoculars may help with comet spotting. Apps like Starwalk can be used to help find the comet.
The comet should reach perihelion (the closest point to the Sun) on 17 September, at which point it will be roughly 0.22 AU from the Sun: that is, just over a fifth of the distance between Earth and the Sun.
This will place it well inside Mercury’s orbit, and it might be so close that the comet breaks up under the Sun’s heat.
If it doesn’t break up, people may be able to spot it in the evening in late September, too.
On website Southern Comets, amateur astronomer Michael Mattiazzo says that Southern Hemisphere observers might be able to see the comet in the constellation Virgo around 23 September.
“You will need a perfectly clear horizon, preferably on top of a mountain,” writes Mattiazzo. “The observation will be difficult, but not impossible.”