Ask Ethan: What Happens When Stars Pass Through Our Solar System?
“How bad would it be if a star passed near the Sun? How close/large would it have to be to pose serious danger? How likely would such an event be?”
Space is a pretty empty place; it’s more than four light years to the nearest star. But despite this, we’re moving through the galaxy at around 220 km/s, passing and being passed by other stars at about 10% of that speed. Over long periods of time, stars occasionally make close passes by our own, meaning that they could pertub the Oort cloud, the Kuiper belt, or (if they got close enough) even the orbits of the planets themselves. Which of these is a realistic concern, and how often do these events actually occur? Moreover, when they do occur, what are the implications for what we’ll experience here on Earth? Will there be a pretty light show? A series of cometary impacts? Or a complete disruption of our orbit?