Brightest Comet of the Year Just Days From Reaching Peak Point—Now Visible to Eye

Comet C2023 A3, also called Tsuchinshan-ATLAS. Shutterstock/BobNoah

Observers have already spotted a comet that could be the brightest of the year with the use of binoculars. Currently just a tiny fleck of light sputtering in space, the newly discovered comet is expected to grow brighter in the coming days.

As Comet ATLAS C/2024 G3 traverses its gargantuan 160,000-year orbit to reach perihelion—its point nearest to the sun—astronomers expect it could become the brightest comet of 2025.

On Jan. 13, the comet that was first discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) on April 5, 2024, will come within 13.5 million kilometres of our closest star. That might seem a great distance, but bear in mind Earth’s distance from the sun is 150 million kilometres, or 1 astronomical unit (AU).

Comets are hunks of ice and cosmic dust floating through space. When heated by solar radiation as they near the sun, their composition becomes volatile and begins to sublimate. The comet then begins to shed its matter through space, often leaving a characteristic tail and nebulous envelope, or coma, around it, causing a glow.

A comet may eventually shed all its matter, which can take eons (or may never happen), and go extinct to become an asteroid—a space rock.

When it reaches perihelion, G3 will be a mere 0.09 AU from the sun. It will graze the sun so closely that experts do not know if it will survive to continue its long journey through the solar system and beyond.

This photo of Comet ATLAS C/2024 G3 was captured on camera by Terry Lovejoy on Jan. 6, when it was magnitude 1.5 and "very obvious with binoculars." Courtesy of Terry Lovejoy

Brightest Comet of The Year?

Astronomers measure brightness in terms of apparent magnitude wherein low measurements denote brighter objects (naturally, limiting factors like a person’s eyesight and atmospheric conditions blur the metrics slightly). Objects of magnitude 6.5 are equivalent to the faintest stars visible to the naked eye. The planet closest to the sun, Mercury, may shine at −2.48 magnitude, while last year’s Comet C2023 A3 reached −4.9 at perihelion.

On its discovery, G3 was observed as a magnitude 19 object. By the end of October last year, it was reportedly between magnitude 5 and 5.5.

On Jan. 6, amateur astronomer and comet discoverer Terry Lovejoy reported on social media that it had reached magnitude 1.5, noting it was already “very obvious with binoculars.”

Lovejoy, who discovered six comets, including C/2011 W3 (Lovejoy), and who works to perfect filters for improving astrophotography, has been tracking the inbound comet’s progress and brightness for months. He photographed G3 from his home in Queensland, Australia.

“The comet appears to be healthy and might be visible in binoculars again towards the end of January in the evening sky,” Lovejoy told The Epoch Times on Jan. 7.

“The most interesting aspect of the comet is, on Jan. 13, it will pass 14 million kilometres from the sun, far closer than any planet, including Mercury, and will be subjected to extreme conditions.”

In less than a week, some predict G3 could peak at magnitude −6.9. That’s brighter than planet Venus (magnitude −4.2) though still dimmer than the moon (−12.6). Astronomer Gideon van Buitenen lists the comet’s peak magnitude at −3.9—still brighter than any star. It’s believed G3 could easily be the year’s brightest.

Comet’s Origins

Comets often travel along enormous orbits around the sun, originating from deep space. When it was first discovered, Comet ATLAS C/2024 G3 was thought to be a newborn comet from the Oort Cloud, a theorized icy debris field outside the solar system.

But now scientists think differently. It’s believed that G3 is actually very old, and that it grazed the sun once before—160,000 years ago. That has instilled confidence that it might survive reaching perihelion again this time.

Since its discovery, G3 has been drifting ever closer to us and gowning ever brighter. It could soon outshine even Venus, the brightest planet in our skies.

Comet ATLAS C/2024 G3 was photographed shining at magnitude 2 on Jan. 3. Courtesy of Terry Lovejoy

Don’t Stare

While it might be tempting to try spotting the comet, doing so is dangerous, as it will be far too close to the sun. At perihelion, the comet will be 5 degrees’ distance from the sun, equal to the width of three fingers held before the sky at arm’s length.

After reaching peak brightness, the comet will begin embarkation on its outbound leg. Swerving away from the sun, it will be safe to observe immediately after sundown and may be visible even to the unaided eye.

Viewing G3 successfully will largely depend where you’re watching from. Those in the Southern Hemisphere may have the best chance.

In late January, the comet will head due-south. Observers in the Northern Hemisphere could possibly spot its tail just poking above the horizon. It will be more obvious from south of the equator, hovering low after sunset.

The bottom line? The brightest comet of the year could peak in less than a week, reaching perihelion on Jan. 13. At that time sighting G3 is ill advised. As the month grows old, though, sky watchers might catch its tail on the way out.