Astronomers have identified a nearby star, now 20 light years away, that 70,000 years ago flew past the solar system at a distance of only 0.8 light years.
The star’s trajectory suggests that 70,000 years ago it passed roughly 52,000 astronomical units away (or about 0.8 light years, which equals 8 trillion kilometers, or 5 trillion miles). This is astronomically close; our closest neighbor star Proxima Centauri is 4.2 light years distant. In fact, the astronomers explain in the paper that they are 98% certain that it went through what is known as the “outer Oort Cloud” – a region at the edge of the solar system filled with trillions of comets a mile or more across that are thought to give rise to long-period comets orbiting the Sun after their orbits are perturbed.
I feel it necessary to note that the Oort Cloud itself has never been directly observed and only exists theoretically based on the random arrival of comets from the outer solar system.