Stargazers are in for a limited edition treat this weekend, as a newly discovered comet will be visible — before going on to disappear from view for some 400 years.
“C/2023 P1 Nishimura” is an icy body around half-a-mile in diameter, and will make its closest approach to Earth on Tuesday, safely passing at a distance of 78 million miles.
After flying past the Sun in about a week’s time at a distance of just 26 million miles, and assuming it survives, Nishimura’s orbit will carry it off into the depths of the solar system.
Astronomers predict that the last time the comet paid Earth a visit was some 430 years ago — about 16 years before Galileo invented the telescope.
As with many comets, Nishimura has a somewhat greenish tinge, a result of radiation from the Sun breaking down a reactive molecule made up of two carbon atoms.
According to astronomers, Nishimura is extremely faint — and so some equipment will be useful in spotting it in the night sky.
NASA’s Paul Chodas said: “You really need a good pair of binoculars to pick it out, and you also need to know where to look.”
Specifically, early rises in the Northern Hemisphere should look towards the northeast around 90 minutes before dawn — the comet will lie less than 10 degrees off the horizon, near the constellation of Leo.
As it gets closer to the Sun over the next few days, the comet will inherently brighten. However, at the same time, it will also drop lower in the sky, making it harder to see.
Balancing these factors, this weekend could well be the best time to spot Nishimura.
Certainly, next week — Virtual Telescope Project founder Gianluca Masi said — represents “the last feasible chances” to spot the comet before it is lost in the Sun’s glare.
The Italian astronomer added: “The comet looks amazing right now, with a long, highly structured tail — a joy to image with a telescope.”
Comets develop tails as they are slowly evaporated by the Sun — with one made up of released dust, and the other of gasses.
While the window to catch Nishimura might be closing for stargazers in the Northern Hemisphere, it should become visible from the Southern Hemisphere by September’s end.
This is assuming it survives its brush with the Sun. While NASA was initially unsure — reporting back in late August that it “may break up” — the prognosis is now more optimistic.
Chodas said: “It’s likely to survive its passage.”
For anyone traveling to the southern hemisphere later this month, comet Nishimura will probably be spottable low on the horizon in the evening twilight.
First spotted back in mid-August, the comet takes its name from the amateur astronomer — Hideo Nishimura — who made the discovery using a digital camera with a telephoto lens.
As Chodas notes, these days it is rare for an amateur to be the one to discover a comet, given how many sky surveys are being carried out by powerful ground telescopes.
However, he added, “this is [Nishimura’s] third find — so good for him!”
The Japanese astronomer previously helped catalog Comet e C/1994 N1 (Nakamura–Nishimura–Machholz) and Comet C/2021 O1 (Nishimura).
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