The Christmas Star Returns

A unique thing which hasn’t been seen for centuries will take place near December 25.

Skywatchers will be in for a treat later this month as Jupiter and Saturn are preparing for quite a show. On the same day as the winter solstice, the two giant planets will align to form a "Christmas star" that has not been seen in about 800 years.

Looking up at the sky this year, skywatchers may have noticed two particularly bright objects that have been traveling together across the sky. These are actually Jupiter and Saturn and they have been moving closer to each other.

On Dec. 21, the same day as the winter solstice in the Northern Hemisphere, the two planets will align in the sky and appear so close together that they will be just a tenth of a degree apart. According to NASA, that’s about “the thickness of a dime held at arm’s length.”

Such an event, wherein the two objects align with the Earth and appear so close together in the sky, is called a conjunction. It typically happens once every 19 or 20 years. But this year’s event is the “great conjunction” between Jupiter and Saturn since they will appear exceptionally close together.

“In fact, Saturn will appear as close to Jupiter as some of Jupiter’s moons,” NASA said, calling the Dec. 21 event the “greatest great conjunction” in 60 years, since Jupiter and Saturn will not appear this close again in the sky until 2080.