A group of astronomers discovered a dim alien star that passed trough our solar system only 70,000 years ago.
The red dwarf star called ‘Scholz’s star’, named afte rits discoverer Ralf-Dieter Scholz, passed our sun at a distance of 0.8 light years. To put this in perspective: Proximia Centauri, our sun’s current closest companion, stands at a distance more than five times as far, at 4.25 light years.
Scientists came tot heir findings on the basis of measurements by telescopes stationed in Chili and South-Africa with which they determined the velocity of the star (among other thing). On the basis of its trajectory it was determined with a certainty 98% that Sholz’s star passed trough the outer Oort Cloud (a cloud made up of billions of comets surrounding our solar system) 70,000 years ago. The findings where published in Astrophysical journal letters
Lead astronomer Dr. Eric Mamajek stated in an interview with the BBC that the effects of sholz’s star on our cosmic neighbourhood where negligible although it is likely that some of the Oort Clouds billions comets were perturbed by it.
Currently Sholz’s star is at a distance of 20 light years from our sun and is way to dim to see, 70,000 years ago however it might have been visible to the naked eye for our ancestors as its magnetic activity might have caused it to flare.
Further reading: http://iopscience.iop.org/2041-8205/800/1/L17/article
BBC interview: http://www.bbc.com/news/science-environment-31519875