Rare ‘Christmas Star’ – Winter Solstice – Ursid Meteor Shower Combine for a Special 2020 Christmas Sky on Monday

The 2020 winter solstice will be a particularly special one as Jupiter and Saturn will be at their closest point for 400 years.

For the past few months, the two gas giants have been approaching each other, and on Monday night December 21, the winter solstice, this process will culminate in a “great conjunction.”

The great conjunction is when the two planets will be so close to each other that they appear like a bright double planet—with the phenomenon being popularly referred to as a “Christmas Star.” They are rare, occurring once every 20 years or so. But this year’s event is exceptional because the planets will appear particularly close to each other.

The last time the planets came this close was around four hundred years ago, according to NASA.

“You can imagine the solar system to be a racetrack, with each of the planets as a runner in their own lane and the Earth toward the center of the stadium,” Henry Throop, an astronomer in the Planetary Science Division at NASA Headquarters in Washington, said in a statement.

“From our vantage point, we’ll be able to be to see Jupiter on the inside lane, approaching Saturn all month and finally overtaking it on December 21.”

The great conjunction of Jupiter and Saturn coincidentally takes place on the winter solstice—the shortest day of the year with the longest night in the Northern Hemisphere—providing ideal conditions to view the astronomical event.

“The solstice is the longest night of the year, so this rare coincidence will give people a great chance to go outside and see the solar system,” Throop said.

While the term “winter solstice” usually refers to an entire day, it technically only refers to a specific moment in time—when the Earth’s North Pole is pointing furthest away from the sun. In 2020, this moment will occur at 5:02 a.m. ET on Monday, December 21—marking the start of astronomical winter in the Northern Hemisphere.

The great conjunction of Jupiter and Saturn is not the only astronomical event stargazers will be able to enjoy around the time of the winter solstice. On the night of December 21-22, the annual Ursid meteor shower is set to peak, according to the American Meteor Society (AMS).

During maximum activity, observers may be able to see 5-10 Ursid meteors per hour during the late morning hours. Some outbursts occasionally produce more than 25 meteors per hour.