A comet that could shine as bright as Venus that would be visible from Earth

A comet that has surprised astronomers could shine as brightly as Venus in the night sky when it passes Earth in the next few days.

Comet C/2024 G3 (ATLAS) was discovered last April by NASA’s Asteroid Terrestrial-impact Last Alert System when it was more than 600 million kilometers from Earth. Astronomers initially assumed it would not survive its close-to-the-sun orbit, but later observations suggested the comet is taking a different path that will allow it to survive and perhaps even remain intact for a flyby of Earth.

This new orbit, which takes 160,000 years for a round trip, causes the comet to wind its way through our solar system in a way that makes it visible to stargazers in the Southern Hemisphere. But for the last part of its journey around the sun, it should also be almost visible with binoculars to people in the northern hemisphere.

Observations since the new orbit was proposed have shown that the comet is growing brighter than expected, which could mean it is breaking up as it travels closer to the Sun. However, recent observations have shown that the brightness has persisted and even increased, which would not be the case if the comet had disintegrated.

If C/2024 G3 survives, it could lead to an unusually bright appearance in the night sky, with some astronomers predicting its brightness will match that of Venus, making it one of the brightest comets in decades.

However, the exact brightness of the comet is uncertain. It can be far enough away to reflect the sun’s light and be clearly visible, or it can be washed out by the sun’s light, making it invisible.

Astronomers have also floated the possibility of a phenomenon called forward scattering, where dust from the comet makes it appear brighter than it normally would, but the chances of this are low, according to meteorologist Joe Rao at Space.com.

If the comet shines brightly, it will probably reach its maximum level around the time of its closest approach to the Sun. The Central Bureau of Astronomical Telegrams, which collects observations from astronomers around the world, predicts this will happen on January 13 at 10.17 GMT, with the comet’s closest approach to Earth occurring a few hours later.

That equates to a viewing window of about three days for those in the Northern Hemisphere hoping to catch a glimpse of the comet, should it be bright enough, from January 12 to 14. For people in places like the US and Europe, the best time to see the comet will be about half an hour before sunrise on January 12, when it should be visible with binoculars, about 5 degrees above the sun or just above the horizon. There should also be another chance to see it about half an hour after sunset on January 14.