Giant Comet From the Oort Cloud Will Pass by the Sun in 2031

Astronomers used about 40 observations of the object, which is called 2014 UN271, to estimate its size and orbit

A photograph shows the NEOWISE comet in the night sky
Like the newly-identified 2014 UN271, the NEOWISE comet pictured here is a long-period comet originating in the Oort Cloud. Photo by NASA Johnson via Flickr under CC BY-NC-ND 2.0

Amateur astronomers, mark your calendars: one of the largest comets ever documented is going to make its closest pass to the Sun in 2031.

The International Astronomical Union’s Minor Planet Center announced new details about the object, including its name, 2014 UN271, on June 19, George Dvorsky reports for Gizmodo. 2014 UN271 is between 62 and 230 miles wide—unusually large for a comet—and it is currently careening through the solar system, traversing about the distance between the Earth and the Sun each year. And at its closest point, 2014 UN271 will be about ten times farther from the Sun than Earth, Michael Irving reports for New Atlas.

2014 UN271 may develop the recognizable coma and tail of a comet as it gets closer. Observations of the object could help astronomers better understand a mysterious region called the Oort Cloud that surrounds our solar system.

Queens University planetary scientist Meg Schwamb tells Gizmodo that she is looking forward to “fireworks” as 2014 UN271 gets closer, especially if it begins to break into pieces. The object’s visit to the inner solar system may also be the birth of a long-period comet. But astronomers will have to wait and see what happens.

“Comets are like cats,” says Schwamb to Gizmodo. “You never know what they’re going to do.”

2014 UN271 was identified based on data collected between 2014 and 2018. Based on the object’s eccentric orbit, astronomers suspect that it originated in the Oort Cloud, a mysterious region of ice and rocks that surrounds the solar system.

The Oort Cloud exists just beyond the reaches of the heliosphere, a bubble of plasma created by the Sun, Abigail Beall reports for BBC Future. It sits about 2,000 to 5,000 times farther in space than the distance between Earth and the Sun.

That means that Voyager 1, a space probe that was launched 40 years ago, is now only one-tenth the distance between the edge of the Solar System and the Oort Cloud. It would take the probe another 300 years to reach the cloud, and by then, its power source will probably be dead.

That’s why comets with unusually long orbits like 2014 UN271 and last year’s NEOWISE offer a better opportunity to understand the makeup of the Oort Cloud. Average comets usual complete their orbits in less than 200 years, but long-period comets can take thousands of years. NEOWISE won’t be back for another 6,800 years; 2014 UN271 could take between 400,000 and one million years to return, per Gizmodo.

“It’s cool that we’re finding it now,” says Schwamb to Gizmodo. “With the Vera Rubin Observatory coming online shortly, we’ll be able to create a movie of how this object will evolve over the next 10 years—we’re going to keep our eyes on this object.”

However, Schwamb notes to Gizmodo that megaconstellations of satellites, such as Starlink, could hamper astronomers at the observatory as they try to study comets like 2014 UN271.

At its current pace, 2014 UN271 will travel from its current point just past Neptune’s orbit to nearly reach Saturn’s orbit in 2031. The object probably will only be about as bright as Pluto’s moon Charon at that point, per New Atlas, so people will likely need to rely on telescopes to capture photographs of it. Then it will head back into distant space.