Wandering stars can nudge comets toward collisions with Earth

The odds of a comet shifting course and heading toward Earth increase slightly when stars drift close enough to the solar system to disturb the comets' orbits, according to a new research paper.
By Kara Menard | Sep 04, 2017
The odds of a comet shifting course and heading toward Earth increase slightly when stars drift close enough to the solar system to disturb the comets' orbits, according to a new research paper. The authors calculated the odds of a star acting on our system's comets and concluded that it has happened several times in Earth's history--and could happen again.

Comets are some of our solar system's most distant objects, according to astronomers, who trace most comets' orbits within a region of space called the Oort Cloud, which lies far beyond Pluto. Astronomers think that occasionally, other stars drift close to the Oort Cloud, and the stars' gravity nudges thousands of comets at a time out of their usual orbits.

A few dislodged comets veer toward Earth, they believe. Some astronomers suspect that the comet that killed the dinosaurs was nudged by a star.

Astronomers project that many stars in our galaxy draw closer to each other at times as they all move in their elliptical orbits around the galaxy's center. This latest paper predicts that 490 to 600 stars will pass within 16.3 light years of our sun, close enough that their gravity might make some comets wobble in their orbital paths.

The paper also predicts that 19 to 24 more stars in the next million years will get within less than 3.26 light years, which is close enough to dislodge some comets completely from their orbits. Not all of them will head toward our planet, but the risk of a collision at some point is real, said Coryn Bailer-Jones, a Max Planck Institute researcher and the paper's lead author.

"Certainly anything coming within that distance you should worry about," said Bailer-Jones.

He added that future studies might track down which stars might be responsible for knocking comets off course.

---

Have something to say? Let us know in the comments section or send an email to the author. You can share ideas for stories by contacting us here.

Comments
Comments should take into account that readers may hold different opinions. With that in mind, please make sure comments are respectful, insightful, and remain focused on the article topic.