New Year brought the spectacle of fireworks lighting up the night sky – but there’s something extra for us at the start of 2018.
While it seems we hear a lot about supermoons these days, they are not that common – and it’s even less common for two to happen in a single month.
January lunar displays will be the only supermoons in the whole year, so they are worth looking out for.
A blue moon is the name given to a second full moon within one calendar month.
This only occurs every three years.
It has given rise to the phrase ‘once in a blue moon’, referring to something that doesn’t happen very often.
On other occasions, the moon can actually appear blue in colour because of the way light bounces off large dust particles thrown into the atmosphere by a volcanic eruption.
There will also be a total lunar eclipse on January 31, 2018.
This eclipse will be visible in much of the USA, northeastern Europe, Russia, Asia and Australia.
During the time of total eclipse, there will be a Blood Moon as the moon’s surface turns a deep red.
So what exactly is a supermoon?
The moon’s orbit around the Earth is elliptical rather than circular, so it comes closer to us at some points and is noticeably farther away at other times.
In 1979, astrologer Richard Nolle coined the term supermoon to describe a new or full moon whose orbit is at (or within 90 per cent of) its closest point to Earth (the perigee).
A supermoon new moon is not visible, but a supermoon full moon is big and bright, appearing 14 per cent larger and 30 per cent brighter than a normal moon.
This broad definition means there are, on average, four to six supermoons a year. There were three in 2017 – in January, November and December – and just two in 2018.
But some define it more precisely, saying a supermoon must be less than 360,000km (223,694 miles) from Earth.
On that basis, the December 2017 supermoon was the only proper one that year and the January 1 supermoon is the only one in 2018.
The supermoon on November 14, 2016, was the closest since January 26, 1948 .
On November 25 , 2034, the moon will be even closer than that.
When the moon is at its farthest point, it is is called a micromoon . That only happens about twice a year.
What effect will the supermoon have on Earth and people?
Supermoons are closer to the Earth, creating stronger gravitational forces than those of a normal full moon and producing higher tides and bigger waves.
The gravitational pull is said to be 20 to 30 per cent stronger – or even as much as 50 per cent.
It means the tide will be around two inches higher than normal. And although that doesn’t sound like much, meteorologists say higher tides combined with high winds could lead to coastal flooding or produce more intense storms.
It’s also thought that supermoons cause a small increase in tectonic activity by exerting a greater gravitational pull on the molten rock beneath the surface of the Earth, making the ground rise and fall just like the tides in the ocean.
This could then put extra strain on fault lines, triggering an earthquake.
Geologists in Japan believe a supermoon led to the powerful New Zealand earthquake in November 2016.
They claim that several other large earthquakes happened at similar times of ‘tidal stress.’
In addition, vets have recorded more cases of injuries to cats and dogs around the time of a full moon – possibly because the animals are active for longer at night because of bright moonlight.
And some scientific studies have found human sleep patterns are affected – with people sleeping for around 20 minutes LESS on and around the day of a full moon.