Got any plans for this weekend? You might want to get out the heavy-duty thermals and stand outside to catch a glimpse of something pretty special.
That’s because Earth will have front row seats for the first and last supermoon of 2017 in the next few days, known as the ‘full cold moon’.
Appearing 14% larger and 30% brighter than the moon usually does, according to NASA, it will be well worth looking out for.
What Is A Supermoon?
NASA says that a supermoon happens when a full moon coincides with the moon’s perigee - meaning the point in its orbit at which it is closest to Earth (the farthest point is known as apogee).
The moon is usually about 238,000 miles away from Earth but when in perigee it is about 222, 135 miles away - that’s a difference of 30,516 miles.
It is this combination of being physically closer to earth and being a full moon that makes it look so much larger and brighter.
“Generally speaking, full moons occur near perigee every 13 months and 18 days, so it’s not all that unusual,” Geoff Chester of the US Naval Observatory told NASA Science News.
When Can I See The Supermoon?
The moon will rise on Sunday 3 December and becomes totally full at 15.47 GMT, though of course it will be big and full all night.
It won’t actually reach perigee – or the point at which it’s closest to Earth – until the next morning at 08.45 GMT.
Where Can I See The Supermoon?
For the best view, you don’t need any special equipment or a telescope; just try to be in a less populated area for minimal light pollution.
The moon will also appear larger or smaller, depending on your view point. If you are looking straight up into the sky, it will appear less impressive than if it is nearer the horizon, where you are more likely to have buildings for scale.
NASA says to look for the full moon in the constellation of Taurus.
Why Don’t Supermoons Happen More Often?
Supermoons don’t happen every month because the moon’s orbit changes orientation as the Earth goes around the sun.
So, the long axis of the moon’s elliptical path around the Earth points in different directions, meaning that a full (or new) moon won’t always happen at apogee or perigee.