Far beyond the orbit of Neptune, trillions of comets left over from the formation of the solar system lie in wait in a region known as the Oort cloud. Here they are kept in relatively stable orbits around the sun, posing little threat to Earth save for the occasional icy rock that ventures inwards. But in the blink of a cosmic eye that could all change.
On Dec 18 German researchers estimated that the passage of a falling star near the Solar System could destabilize the balance of the Oort Cloud and trigger an authentic comet shower in Earth. Although it is a very remote possibility, since the closest star to Earth is Proxima Centauri, located about four light years away, the reality is that all the stars in the galaxy are in constant motion; therefore, some event of this kind could happen and bring unpleasant consequences.
A local orange dwarf star has a 90 percent probability of passing within the orbit of our outer solar system’s Oort Cloud between 240,000 and 470,000 years from now, says the author of a new study detailing the computer-modeled orbits of more than 50,000 nearby stars.
In a paper just accepted for publication in the journal Astronomy & Astrophysics, Coryn Bailer-Jones, an astrophysicist at Germany’s Max Planck Institute for Astronomy in Heidelberg, and the paper’s sole author, found that of 14 stars coming within 3 light years of Earth, the closest encounter is likely to be HIP 85605, which now lies some 16 light years away in the constellation of Hercules.
Sure, that’s a long way off, but this unwelcome guest could perturb the Oort cloud, flinging dangerous comets towards Earth.
“If there are people around at that time in the future and they look up in the night sky, they wouldn’t particularly notice the star.” Coryn said.
“Calculation of one object suggests it would be slightly brighter than Venus, which is pretty bright, but not as bright as the moon or sun or anything.” But he says such an encounter is ‘inevitable,’ although the chances of a star actually entering the solar system is close to zero. “To truly know how much danger we will be in, though, more data is needed.”, he added.
If the comets (sent by the star) don’t kill us, there is still the threat of radiation from a star turning supernova as it moves through the galaxy which could also end life on Earth. This could kill outright, or destroy the ozone layer so the that damaging UV radiation could wipe out all living things.