A faint star in the serpent is getting closer — in more ways than one. For one thing, it’s moving toward us at about a third of a million miles per hour. And for another, every time astronomers recalculate how close the star will pass from the Sun, the distance goes down.

Today, Gliese 710 is about 64 light-years away. It’s in the constellation Serpens, in the east-southeast in early evening. But the star is fairly small and faint, so it’s far too dim to see with the eye alone.

Because it’s rushing toward the solar system, though, that won’t always be the case. In about 1.3 million years, it’ll be quite bright — as bright as Mars appeared last fall.

A couple of decades ago, astronomers calculated that the star would pass roughly one light-year from Sun and Earth. Since then, a space telescope has provided more accurate readings of its distance and its motion through space. With that, astronomers cut the minimum range to half a light-year, then a quarter. And a few months ago they cut it to just one-sixth of a light-year. By comparison, the closest star today is more than four light-years away.

With such a close approach, Gliese 710 should plow through the Oort Cloud — chunks of rock and ice that orbit far from the Sun. The star’s gravity could push some of them toward the inner solar system, where they could hit Earth — perhaps wiping out much of our planet’s life in that far-distant future.
 

Script by Damond Benningfield

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