The largest comet ever discovered is coming into view after a long and slow trip from the far reaches of the solar system. First spotted in 2014, comet C/2014 UN271, also known as Bernardinelli-Bernstein, has slowly been making it's way closer to the sun. After seven years of traveling through the void, the comet is getting to a point where it is more visible than ever. What scientists are seeing is incredible. Bernardinelli-Bernstein is massive.
The average comet measures roughly 6 miles across in diameter and preliminary observations put Bernardinelli-Bernstein at over 60 miles across. This makes it ten times larger than the average comet and scientists say it could be even larger.
The comet is in an extremely long orbit that removes it from our sight for millions of years at a time. Such a long orbit gives the comet time in the icy reaches of deep space to pick up debris and grow before returning towards the warmth of the sun which usually melts and shrinks comets. Bernardinelli-Bernstein wasn't in the confines of our solar system for over 3 million years, but it is back.
This is a prime example of a deep space, Oort Cloud, comet which originated and spends most of its time far beyond the boundaries of our solar system but remains locked in an ancient orbital path around the sun.
Despite the incredible size of Bernardinelli-Bernstein astronomers say there is no need to worry. The orbital path of the object is so odd and elongated the comet will never get near enough to Earth to pose a threat. Unfortunately, that also means that it will not be visible to the naked eye either like some other famous comet appearances.
Over the next decade, this object will continue to slowly make its way through the solar system. Intrepid amateur astronomers will be able to catch glimpses of the comet as it passes near Saturn in the coming years but it will be a hard thing to spot.
As the comet gets closer to professional observatories here on Earth scientists will be able to get a better read on it and determine its exact size. High-end estimates put it at over 100 miles in diameter which would make it the largest comet discovered by far. For comparison, the most famous comet, Halley's Comet, is roughly 4 miles in size. Even on the more conservative end, Bernardinelli-Bernstein is fifteen times larger than that.
The appearance of the comet is helping astronomers understand the erratic orbits of deep space objects around our sun as well as deepening their understanding of how comets form, travel, and evolve over millions of years. Bernardinelli-Bernstein will be a hot button topic for astronomy for years to come as it continues to meander through our slice of space.
If Bernardinelli-Bernstein ever got as close to Earth as Halley's Comet it would put on one of the greatest light shows ever seen.