Adam Smith wrote this article in The Independent:

The largest comet ever detected, Bernardinelli-Bernstein, is heading back towards our Solar System.

The comet is located 29 astronomical units (AU) away - 29 times the distance between the Earth and the Sun - and so is set to arrive in approximately a decade, according to new research published on the preprint server arXiv.org.

Right now, the 93-mile-wide comet is located in the Oort cloud, a huge array of icy rocks the size of mountains, but a glowing tail or “coma” behind it is a signifier that it is approaching the warmer inner solar system.

Fortunately, the giant rock does not pose a threat to the planet and will likely pass by the planet outside of Saturn’s orbit, 10.97 AU away from the sun. This means that humans will not be able to see the comet without using equipment, such as telescopes, but it is significantly closer than the comet’s most recent approach.

The last time that Bernardinelli-Bernstein returned, 3.5 million years ago, it came within 18 AU of our Sun, before travelling 40,000 AU away.

"We conclude that BB is a ‘new’ comet in the sense that there is no evidence for [a] previous approach closer than 18 AU," the researchers wrote, quoted in LiveScience.

The comet was first spotted 4 billion kilometres from our solar system in 2014, roughly the same distance as Neptune.

“My phone didn’t stop ringing-I wasn’t expecting the reception the [scientific] community gave to the discovery,” Pedro Bernardinelli, postdoctoral researcher at the University of Washington, told National Geographic.

Studying the comet is crucial to scientists’ understanding of the early history of the solar system, scientists have said, and could reveal more about the mysterious Oort Cloud.

Although Bernardinelli-Bernstein will almost certainly not be harmful to Earth, space agencies are developing contingency plans for more dangerous threats from space.

Chinese researchers want to send 23 Long March 5 rockets from the country to practise diverting asteroids away from Earth. They will target asteroid Bennu, which will come within 7.5 million kilometres of Earth’s orbit with a 1-in-2700 chance of hitting the planet between 2175 and 2199.

Nasa, meanwhile, is targeting a rock called Didymos - around the size of the Great Pyramid of Egypt - by deliberately crashing a spacecraft into it in an attempt to change its motion in space.