Mega-Comet: Everything You Need To Know About The Mysterious Ice Monster From Half A Light-Year Away
A huge comet so large it’s classified as a “minor planet” has been spotted beyond Uranus coming into the inner Solar System for a once-in 600,000-years visit.
Thought to be a rare long-period comet visiting from as far as half a light-year away, C/2014 UN271 (Bernardinelli-Bernstein)—hence be known as Comet Bernardinelli-Bernstein—is an incredible find and sure to be a major talking point in astronomy until its closest approach in 2031.
Here’s everything you need to known about the “comet of the decade:”
What and where is Comet Bernardinelli-Bernstein?
It’s a huge object first discovered about 29 astronomical units (AU) away from the Sun in our Solar System. For context, Earth is one AU from the Sun and Neptune is 30 AU.
Hence Comet Bernardinelli-Bernstein’s initial classification as a trans-Neptunian Object (TNO), which is defined as a minor planet or dwarf planet in the Solar System that orbits the Sun at a greater average distance than Neptune.
According to the latest observations from Las Cumbres Observatory-Sutherland in South Africa, it’s now about 20 AU from the Sun, which is outside the orbit of Saturn.
How big is Comet Bernardinelli-Bernstein and is it dangerous?
It’s rated as “up to” 230 miles/370 kilometers across, but it’s more likely to be about 62 miles/100 kilometers. It sports the largest comet nucleus ever seen. However, Comet Bernardinelli-Bernstein will not strike Earth.
Given its size, that’s just as well. Comet Bernardinelli-Bernstein is one of the biggest comets ever found, the largest being Comet Sarabat (C/1729), the so-called “Great Comet of 1729” that was easily visible to the naked eye.
An initial study of data from that six-year mission (2013-2019) published last year found 318 TNOs. This latest search has turned-up another 800 objects—including Comet Bernardinelli-Bernstein.
Where has Comet Bernardinelli-Bernstein come from and where is it going?
Comet Bernardinelli-Bernstein is a long-period comet of unknown origin, but it’s thought it could be from the farthest reaches of the Solar System about half a light-year from the Sun.
Long-period comets take more than 200 years to complete an orbit around the Sun, but this one is reckoned to on a 600,000-years orbit. Comet Bernardinelli-Bernstein comes from the Oort Cloud, a spherical cloud of icy objects from 50,000 to 100,000 AU from the Sun that surround the Solar System. It’s reckoned that this comet could even be from as far as 60,000 AU.
Like all comets, this one will round the Sun and head off back to where it came from, but the closest it will get to the Sun will be 10.5 AU.
The closest a comet gets to the Sun is called its perihelion. Comet Bernardinelli-Bernstein’s perihelion won’t happen until 2031, so it looks set to be studied for the next decade at least.
When can we see Comet Bernardinelli-Bernstein?
Despite its massive size Comet Bernardinelli-Bernstein sadly won’t ever get close enough to Earth for us to have a look naked-eye. That’s a shame because it’s three times larger than the biggest comet photographed so far—Comet Hale-Bopp in 1997—which wowed the world (more so than “lockdown comet” NEOWISE last summer).
In fact, it will only reach magnitude +17 as seen from Earth, which is well out of reach for backyard telescopes.
The good news is that huge telescopes will likely get some great shots—and they could also find a lot more massive comets like Comet Bernardinelli-Bernstein …
Can we send a spacecraft to visit Comet Bernardinelli-Bernstein?
Since Comet Bernardinelli-Bernstein is going to be in the inner Solar System for about a decade it’s possible a mission will be sent to study it.
After all, it’s from the very farthest edges of the Solar System—60,000 AUs distant—which isn’t a region that’s possible to travel to in a human lifetime.
The European Space Agency has a mission called Comet Interceptor that will launch in 2029 in the hope of snagging a long-period comet as it enters the inner Solar System. Seems perfect? It does, but sadly Comet Bernardinelli-Bernstein’s closest point to the Sun—10 AU—is a major problem. That’s about the orbit of Saturn, which is sadly beyond the capabilities of a solar-powered spacecraft like Comet Interceptor (the current farthest solar-powered spacecraft is NASA’s Juno at Jupiter, which is about 5 AU from the Sun).
Will we find more mega-comets?
There are decent chances that someone will launch another, nuclear-powered spacecraft to study Comet Bernardinelli-Bernstein, but meanwhile we do have a huge new observatory that’s ideal for tracking it to its perihelion and beyond.