(CNN) – The two largest planets in our solar system are coming closer together than they have been since the Middle Ages, and it’s happening just in time for Christmas — hence the nickname of the “Christmas Star.”

While it’s not an actual star, the two planets will certainly make a bright splash in the night sky. On the night of December 21, the winter solstice, Jupiter and Saturn will appear so closely aligned in our sky that they will look like a double planet. This close approach is called a conjunction.

The fact that this event is happening during the winter solstice is pure coincidence, according to NASA. “Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare because of how close the planets will appear to one another,” said astronomer Patrick Hartigan, a professor of physics and astronomy at Rice University in Houston, in a statement.

“You’d have to go all the way back to just before dawn on March 4, 1226, to see a closer alignment between these objects visible in the night sky.” If you’re a stargazer, you’ve likely noticed Jupiter and Saturn have been getting closer together since the summer.

And they’re currently visible in our night sky, inching ever closer to one another. Between December 16 and 25, they will become even cozier. Look for the Jupiter-Saturn conjunction low in the western sky for about an hour after sunset each evening during this time. READ MORE