Jupiter and Saturn will be closer than in several centuries 0:34
(CNN) -
The two largest planets in our solar system are getting closer than they have been since the Middle Ages, and that is happening just in time for Christmas.
So there is a lot to see in the last month of 2020.
On the night of December 21, the winter solstice, Jupiter and Saturn will appear so aligned in our sky that they will look like a double planet.
This close approach is called a conjunction.
'The alignments between these two planets are quite rare, they occur once every 20 years or so.
But this conjunction is exceptionally rare because of how closely the planets will be seen, ”said Rice University astronomer and professor of physics and astronomy Patrick Hartigan.
"We would have to go back to just before sunrise on March 4, 1226 to see a closer alignment between these visible objects in the night sky."
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If you are a star gazer, you have probably noticed that Jupiter and Saturn have been 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 be even closer.
Look for the Jupiter-Saturn conjunction in the western sky for about an hour after sunset each night during this time.
"On the night of the closest approach, December 21, they will look like a double planet, separated by only 1/5 the diameter of the full Moon," Hartigan said.
"For most telescopes, each planet and several of its largest moons will be visible in the same field of view that night."
While these two planets may seem close, they are still hundreds of millions of kilometers apart, according to NASA.
Where will Saturn and Jupiter meet
Clear skies will have to be expected because the conjunction will be visible all over the world, with the best perspective for those near the equator.
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"The further north a viewer is, the less time they have to glimpse the conjunction before the planets sink below the horizon," Hartigan said.
The planets will be bright enough to be seen at twilight, which may be the best time for many American viewers to observe the conjunction.
"By the time the skies are completely dark in Houston, for example, the conjunction will be only 9 degrees above the horizon," Hartigan said.
"Seeing that would be manageable if the weather cooperates and you have a clear view to the southwest."
If you are in New York or London, or those latitudes, try to detect the conjunction just after sunset.
Waiting an hour after the Sun sets will bring the planets closer to the horizon, making them more difficult to detect.
The best conditions for viewing this astronomical event will include a clear horizon to the southwest and no low clouds in the distance, Hartigan said.
Using binoculars or a telescope can help you distinguish the planets.
A telescope would allow us to see Saturn's rings and the brightest moons of both planets, he said.
When will it happen again
If you miss this conjunction and want to see the planets in the same proximity, a little higher in the sky, that won't happen until March 15, 2080, and not again until after the year 2400.
Between the year 0 and 3000 CE or the Common Era, only seven conjunctions were or will be closer than this, 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.
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