Comet Atlas is heading our way, and it could become the brightest comet seen in northern skies in decades.

Comet Atlas is racing toward the inner solar system, and it could become the brightest comet seen in the night sky in over two decades. The comet, discovered by an observatory designed to protect Earth from asteroids, may even be visible during the day just two months from now.

Also known as C/2019 Y4, this comet was discovered by astronomers at the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Hawaii in December 2019. At the time, the comet was exceedingly dim — but the comet became 4,000 times brighter in just a month. This increase is far greater than astronomers predicted, and could potentially signal the comet may soon be exceptionally bright.

Comet Hale-Bopp, seen here on April 6, 1997, was the last great comet seen from the northern hemisphere. Image credit: Giuseppe Donatiello

“Comet ATLAS continues to brighten much faster than expected. Some predictions for its peak brightness now border on the absurd,” stated Karl Battams of the Naval Research Lab.

Comets are, essentially, dirty snowballs. As the comet approaches the Sun, the heat will drive off some of the ice which makes up the nucleus (main body) of the object. If the comet holds it shape as it continues to heat, then Comet Atlas could grow as bright as the planet Venus (the brightest object in the night sky other than the Moon).

The comet, currently near the orbit of Mars, is closely following the path taken by one of the great comets in history — the Great Comet of 1844.

At its current rate of brightening, Comet Atlas could be visible to the naked eye, under dark skies, during the first weeks of April. For skywatchers in the northern hemisphere, this would be a sight unseen since the dual shows of Comets Hyakutake in 1996 and Hale-Bopp the following year. When Hyakutake was at its peak, the tail of the comet stretched halfway across the sky.

Comet Atlas photographed on March 6, 2020. The head (or coma) of the comet is roughly twice as wide as the planet Jupiter. Image credit: Michael Jäger

In May, the comet could shine with a green hue, providing a unique view for viewers in the northern hemisphere.The brightest predictions for the comet suggest it could become bright enough to be seen during the day.

The peak brightness of Comet Atlas would depend, largely, on how much material is encased within its nucleus. If the comet is sizable, and it does not fall apart as it is heated by the Sun, it could put on an amazing show in May.