Jupiter and Saturn will look like a double planet just in time for Christmas

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 narrow approach is called a conjunction.

“Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare due to the closeness of the planets to each other,” the astronomer said. Rice University and physics and astronomy professor Patrick Hartigan in a statement.

If you are an astronomer, you have probably noticed that Jupiter and Saturn are getting closer since the summer. And they are currently visible in our night sky, getting closer and closer to each other.

But between December 16 and 25, they will become even more cozy. Look for the Jupiter-Saturn conjunction low in the western sky for about an hour after sunset each evening during this time.

“On the evening of the closest approach December 21 (embers), they will look like a double planet, separated by only 1/5 of the diameter of the full moon,” Hartigan said. “For most viewers, each planet and several of their larger moons will be visible in the same field of view that evening.”

Hopefully a clear sky as the conjunction will be visible around the world, with the best prospect for those near the equator.

“The farther north a viewer is, the less time they will have to see the conjunction before the planets sink below the horizon,” Hartigan said.

The planets will be bright enough to be seen at dusk, which may be the best time for many American viewers to observe the conjunction.

“By the time the sky is completely dark in Houston, for example, the conjunction will be just 9 degrees above the horizon,” Hartigan said. “It would be manageable if the weather permitted and you had a clear view to the southwest.”

If you are in New York or London, or along those latitudes, try to spot the conjunction right after sunset. Waiting an hour after sunset will only bring the planets closer to the horizon, making them harder to spot.

The best conditions for seeing this astronomical event will include a clear southwest horizon and no low clouds in the distance, Hartigan said. Binoculars or a telescope can help you distinguish planets. A telescope would make it possible to see Saturn’s rings and the brightest moons of both planets, he said.

If you miss this conjunction and want to see the planets with the same proximity, just higher in the sky, it won’t happen until March 15, 2080 – and not yet until 2400.

Between 0 and 3,000 CE, or common epoch, only seven conjunction were or will be closer than this one – and two of them were too close to the sun to be seen without a telescope, according to Hartigan. So, yes, this is an incredibly rare event.