The once-in-a-lifetime alignment will be visible just after sunset on 21 December - the winter solstice.
People looking up at the sky on that date will see Jupiter and Saturn closer than anyone else currently alive has.
"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," Rice University astronomer Patrick Hartigan said 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."
Jupiter and Saturn have been approaching each other in Earth's sky since the summer, and will be separated by less than the diameter of a full moon during the Christmas period from 16-25 December.
Jupiter and Saturn should be visible to anyone on Earth as long as the weather is not too cloudy and allows an unrestricted view at the incredible event.
"On the evening of closest approach on Dec 21 they will look like a double planet, separated by only 1/5th the diameter of the full moon," said Professor Hartigan," explains Hartigan.
"For most telescope viewers, each planet and several of their largest moons will be visible in the same field of view that evening."
The best views will come about an hour after the sun sets. This is when the planets will appear low in the western sky and will look better nearer the equator.
If you happen to miss Jupiter and Saturn's rare meeting, there will be another chance... in 2089. If you happen to have plans and miss that date you can always catch it again... in 2400.
Best tell your future grandkids to tell their future grandkids to be prepared!