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Super Blue Blood Moon

09 February 2018

If you've been anywhere near the news lately, you've probably come across the most recent lunar event to cross our skies - the super blue blood moon at the end of January. The photos from the night are incredible, but what exactly was this amazing phenomenon? The super blue blood moon was the result of three lunar events that all happened to coincide on the night of the 31st of January -a supermoon, a blue moon and a blood moon. 

A supermoon occurs when the Moon reaches the point in its orbit at which it is closest to Earth, which makes the Moon appear larger than usual. There are around 12-13 full moons in one year, and usually 3-4 of them are supermoons. 

A blue moon has nothing at all to do with the colour of the Moon - it refers to the second full moon in one calendar month. The length of our calendar months and the length of the moon phase cycle are very close, but not quite the same. This means that most months will only have one full moon, but because of that little bit of difference, every so often (every 2.7 years), two full moons are squeezed into one month. 

A blood moon is a total lunar eclipse, which occurs when the full Moon passes completely into the Earth's shadow (as opposed to a partial lunar eclipse, which is when only part of the full Moon passes into the Earth's shadow). During a total lunar eclipse, the Moon is completely blocked from direct sunlight by Earth's shadow, so the only visible light that reaches the Moon is the light that is refracted through Earth's atmosphere. Thanks to a phenomenon called Rayleigh Scattering, this refracted light gives the moon a reddish colour, which is where the term 'blood moon' comes from. 

Each one of these events is interesting enough on its own, but at the end of January they all coincided! No matter how you look at it, this event is rare, but exactly how rare depends on where you live. For those living in North America, the last visible blue blood moon (but not supermoon) occurred in 1866, but for those living in Australia, the last visible super blue blood moons occurred on 30th December 1982 and 30th December 1963. But if you missed the big event (or you just can't wait until the next one), don't worry! The 'blue' part of this event doesn't have any effect on what you actually see, and super blood moons (or supermoon total eclipses) occur every few years. Blood moons by themselves are even more frequent - the next one will occur on 27th July this year! 

If you find the workings of space as fascinating as we do, then why not share that wonder with your kids? Hinkler's brand new Know and Glow: Space Sticker Activities is the perfect introduction to the Solar System for kids aged 7-12, complete with glow-in-the-dark stickers to make learning a fun and illuminating experience!