Watch a video of ITV Weather presenter Chris Page talking about the Great Conjunction on ITV News Anglia
Some will call it the Christmas Star, others will refer to it as the Great Conjuction of 2020.
It might happen every 20 years, but this year's Great Conjunction will see Saturn and Jupiter in their closest appearance in the night's sky since 1226 - that's before the first telesope was invented.
What is a conjunction?
This is where two objects in space appear close to each other in the night's sky as their orbits align from the view of the observer. However, in reality, they are thousands, ifs not millions, of miles apart
So what is happening?
Since October the two brightest and largest planets in our solar system, Jupiter and Saturn, have been moving ever closer together in the night's sky. And on Monday 21 December, coincidentally the winter solstice, they will be within 0.1º of each other. That's about the thickness of a Dime chocolate bar at arms length.
The last great conjunction occurred in 2000, but both planets were so close to the sun it wasn't visible with the naked eye. In fact, you have to go all the way back to the 4th March 1226, over 800 years ago, when they were closer than they shall appear on December 21st.
How can I see it?
It will be visible across the world in the western horizon within 1 hour after the sun has set. You can see the planets now as they get ever closer together in the night's sky, before "nearly touching" on December 21st. Look out for the thin cresent moon and two bright objects next to it.
Of course, you'll need to have clear skies, and you can check the latest National ITV Forecast here