4 days ago
The mysterious 'dark comets' prowling our Solar System
These strange objects could explain how water arrived on Earth, but may also be a previously unrecognised threat to our planet. Now, a spacecraft is headed towards one to investigate.
They are some of the strangest rocks in our Solar System. They aren't quite asteroids and not quite comets, but a bizarre mixture of the two. These are "dark comets" – and no-one knows quite what to make of them.
Yet, these mysterious, recently discovered space rocks might be an entirely new class of object in the Solar System that could help to answer questions about how water originated on Earth, according to the scientists trying to study them. They may also pose a previously unrecognised threat to our planet.
And now we have a chance of finding out more about these strange objects thanks to a Japanese spacecraft racing towards one – by complete coincidence – right at this moment. When it gets there in 2031, we might find out for certain what exactly these objects are and how they behave.
The first hint of dark comets emerged in 2016, when astronomers found what they thought was an asteroid that behaved like a comet. While asteroids are rocky, inactive objects commonly found in a wide belt between the planets Mars and Jupiter, comets are rock and ice that have huge tails stretching for millions of miles and tend to originate from the outer solar system.
