Humans walking around 70,000 years ago might have been surprised by an unusual sight in the night sky: the faint flares of another star in our solar system, far more distant than our own sun but nearer than any other known star has ever been to Earth.
A star designated WISE J072003.20-084651.2, also called "Scholz's star" (after its discoverer, Ralf-Dieter Scholz), is a red dwarf currently located 20 light-years away. But 70,000 years ago, it would have been just 0.8 light-years from the sun, a distance that places it within the outer boundaries of our solar system, reports the BBC.
The finding comes after a team of researchers at the University of Rochester, New York, led by Eric Mamajek, carefully measured the dim star's trajectory as it moves away from our solar system. In the paper, the researchers projected the star's movements in reverse, and believe with 98 percent certainty that Scholz's star would have once traveled through what's called the Oort Cloud, the outer region of our solar system where many comets originate.
The red dwarf is an incredibly faint star, so even at its relatively close distance it would have only been visible with the naked eye from Earth if it flared. But flares are not uncommon among magnetically active stars like Scholz's.
Even more incredible, Scholz's star was not alone. It was accompanied by another object known as a brown dwarf, which are bodies just barely lacking enough mass to become stars themselves.
An alien star passing through the outer reaches of our solar system almost certainly would have had an effect on the trajectory of comets hovering in the region, according to the study, which appeared in the Astrophysical Journals Letters — possibly even hurling a few of them toward us in the inner solar system. The good news is that any perturbed comets would probably take about 2 million years to get to the inner solar system, according to the study. And Mamajek believes the effects of Scholz's star on our cosmic neighborhood were most likely "negligible."
So Scholz's star shouldn't have triggered any doomsday scenarios, though we may not know for sure until a couple million years have passed.
Related on MNN: