A Supermoon is a recent term. Often used to describe a full Moon nearer than 360,000 km (224,000 miles) near perigee. Its closest point to earth. The Full Moon can appear larger than usual. Up to 14% compared to when the Moon is at apogee – its furthest point away from Earth.
A casual observer may in fact not even realise there is a Supermoon unless otherwise informed. As the apparent size to the naked eye is negligible. It is slightly noticeable but not dramatically so. However, there is an obvious difference in brightness with a Full Moon at Perigee. The brightness can be as much as 30% brighter than when the full Moon is at apogee. A Minimoon.
A little Bit of Hype
Many traditional astronomers dislike the term “Supermoon” branding the expression as hype or sensationalism. In a way the are quite right! But in another they need to realise this is kind of a good thing. If you are sensitive to your surroundings as I am. You will notice quite a difference compared to other times the Moon is full. Hyping up these events in a way is a good thing as it gets more and more people looking up who wouldn’t normally. The only thing we have to do is manage their expectations. Astronomy can blow peoples minds, but do it wrong and all you will hear people say is a deflated “is that it?”
So in a nutshell. A supermoon is a full Moon that is closer than normal. It can appear ever so slightly larger – not obviously larger. But it can be much brighter than usual.
The Moon can appear rather large when it is low in the sky close to the horizon. This can happen during any full Moon and is an illusion. The Moon Illusion.
When is the Supermoon
There are three Supermoons in 2019. There was one back in January which was also a lunar eclipse. February 19 and march 21.
The largest/ nearest, or brightest whatever way you want to put it is on February 19. 2019 at 3:53 pm perfect timing for viewing it that evening.
February’s Full Moon has another older name that originates in ancient folklore. The Snow Moon. Other names from European and North American traditions are the Hunger Moon or Storm Moon. You can find out more about the Full Moon in February in our February 2019 Night Sky Guide