It's a very rare celestial phenomenon, so it's no wonder everyone's getting quite excited about it.
We probably know more about our star signs from the back of the newspaper than we do about actual astronomy, but scientists have assured us that this is going to be the biggest supermoon that anyone has witnessed in living memory.
Whay is this? Well, it's because of the moon's orbit around the earth which will be at its closest for more than 70 years, making it an incredible spectacle for photographers and star gazers around the globe.
https://twitter.com/Learntoskywatch/status/797876699224481792
Already people around the world have been gazing in amazement at the night sky - and Sunday evening was only a dress rehearsal for the main event tonight.
The supermoon will reportedly be at it's fullest, brightest and most fantastically dazzling on Monday evening, but that didn't stop people from going outside and snapping some pretty incredible shots of the rare occurrence.
https://twitter.com/StormHour/status/797877442513870848
The last time the Moon was this close was reportedly back in 1948 and we may not see another one like this until November 25, 2034 (that's the year, not the time).
The reason for this massive moon is because of the rocky satellite's orbit around the earth being elliptical rather than uniformly circular.
So as the moon revolves around the earth it's sometimes close and sometimes further away - but it's when a full moon falls on the day that it's closest to the Earth that we get a larger-looking Moon.
Some of people's pictures have been quite impressive.
https://www.instagram.com/p/BMw3Rn6ggDE/
https://www.instagram.com/p/BMw3VKoh1Bc/
https://www.instagram.com/p/BMw3XksDNjE/
https://www.instagram.com/p/BMwjFQcAL3q/
https://www.instagram.com/p/BMwaYaujLh9/
https://twitter.com/DrummerBoy2112/status/797910713981399040
https://twitter.com/r_hollingworth/status/797896873822605312
https://twitter.com/WillJMartindale/status/797876097354530817
https://twitter.com/MHardy_Photo/status/797859434122842112
https://twitter.com/BBCWthrWatchers/status/797849877254381568
https://twitter.com/Stephencheatley/status/797840137241640960
