The universe comes calling.

Astronomers around the world are sitting on the edges of their seats right now, waiting to see if yet another comet from another sun has invaded the solar system.

The first such interstellar invader ever detected, a cigar-shaped rock called Oumuamua, caused a sensation when it was seen streaking away from our sun in the fall of 2017. Some astronomers even considered the possibility that it was an alien artifact. But irregularities in its outward trajectory suggested that it was more likely a comet from another star system being jerked around by unseen jets of gas erupting from its surface. It has since passed out of sight.

That is not the case with the new object. Originally labeled gb00234, and now provisionally named C/2019 Q4 (Borisov), it is still on its way toward the heart of the solar system.