After 3.5 million-year hiatus, the largest comet ever discovered is headed our way

According to new research published on, an enormous comet, possibly the largest ever detected, is heading toward the inner solar system. Its arrival time is estimated to be 10 years.
The comet, known as the Bernardinelli-Bernstein comet (or C/2014 UN271, in astro-speak), is at least 62 miles (100 kilometers) across about 1,000 times more massive than a typical comet. According to the statement that announced the discovery of the comets in June 2021, it is so massive that some astronomers mistakenly thought it was a dwarf planet.

However, closer inspection revealed that the object was speeding through the Oort cloud, a huge scrapyard of icy rock billions of kilometers from Earth. It appeared to be heading our direction, and even had a glowing tail (or "coma") behind it, which was a clear indicator of an icy meteor approaching the warmer inner solar system.

Related: 12 of the most bizarre objects in all of existence

Researchers have now done more detailed analysis of the comet and have updated their estimates on its path to the sun.

The enormous rock is not a threat to Earth, for one. Right now, Bernardinelli-Bernstein (BB) is cruising through the Oort cloud at about 29 times the distance between Earth and the sun, or 29 astronomical units (AU). According to scientists, the closest approach of the comet to Earth will be in 2031. This is when scientists expect the comet to pass within 10.97 AU (or 29 astronomical units) of the sun.

Although it is far enough away from Earth that people won't see the comet with telescopes, it is still closer than the rock's last trip to our solar system. The study authors calculated that comet BB passed within 18 AU of Earth's sun after modeling its trajectory.

According to researchers, the comet has traveled as far as 40,000 AU since then. It is now deep within the Oort cloud.

The researchers concluded that BB was a 'new comet' in that there is no evidence of [a] previous approach that is closer to 18 AU. In other words, it is something that humans have never seen before.

Our current view of the comet is a result of the Dark Energy Survey (DES), a project that studied the expansion of space between August 2013-January 2019. The survey saw astronomers map 300 million galaxies in southern sky and discover more than 800 unknown objects that orbited Neptune. The Bernardinelli-Bernstein comet was one of those objects.

As the comet approaches Earth, scientists have ample time to study it. Scientists may be able to get a better understanding of the chemical composition of the early sun by taking a closer look at this rock. Comets that originate deep within the Oort cloud appear relatively unchanged since their removal from the sun many billions of year ago. It will be a rare opportunity to see the early solar system, with millions of years between the next comet's close approach and the one before it.

Original publication on Live Science