‘Super blue blood Moon’ lights up the sky

West to East: The Moon rises over hills in Vladivostok in Russia's Far East. © Getty

Why are coincidences so interesting? Yesterday morning a large, reddish Moon heralded an incredibly rare celestial convergence. What do coincidences say about the way we think?

For the first time in 152 years yesterday, star-gazers in North America, as well as parts of Asia and the Pacific, were treated to the rare site of a super blue blood Moon.

It sounds apocalyptic, so let’s break it down into its component parts.

Super. A supermoon is when the Moon is full at the same time as when it is closest to Earth. The result is that the moon appears larger than normal.

Blue. This refers to the instance when there is a second full moon in a calendar month.

Blood. A blood Moon is the moment during a lunar eclipse when the moon, in the Earth’s shadow, takes on a reddish tint.

Taken individually, none of these events are especially remarkable. But the three happening simultaneously is a genuinely extraordinary coincidence.

Some coincidences are even unlikelier. For example the author Mark Twain was born on the day of the appearance of Halley’s Comet in 1835, and died on the day of its next appearance in 1910.

“What are the chances of that?” Well, very low. But then, as statistician David Hand says, “Extremely improbable events are common,” given the huge number of things that happen on Earth.

So why are we so entranced by coincidences?

Beating the odds

Their sheer unlikeliness, reply some. Simply trying to work out the infinitesimal chance of a super blue blood Moon happening is fascinating. The surprising regularity of coincidences reminds us of the vastness of reality, while also making the world seem very small indeed.

They are interesting because of what they say about us, respond others. People can be very liberal when they consider coincidences — you might consider it a coincidence that another friend shares your birthday, even though this is quite likely. People have surprising experiences, and they are desperate to find meaning out of them.

You Decide

  1. Why are coincidences so interesting?


  1. Find a famous historical coincidence and try your best to work out the probability of it happening.

Some People Say...

“A coincidence is in the eye of the beholder.”

Professor David Spiegelhalter

What do you think?

Q & A

What do we know?
Yesterday an extremely rare celestial happening took place. It has been dubbed a “super blue blood Moon” and combines three unusual, yet relatively common events.
What do we not know?
Whether humans will ever overcome their incredulity at coincidences, given that they are bound to happen thanks to the laws of probability.

Word Watch

The most recent Supermoon took place on December 4th 2017. It was the only such event of the year and was visible in much of the USA.
Lunar eclipse
This occurs when the Moon passes directly behind the Earth into its shadow. It can happen only when the Sun, Earth, and Moon are aligned in "syzygy", with the Earth in the middle.
Mark Twain
Most famous for writing The Adventures of Tom Sawyer and its sequel, The Adventures of Huckleberry Finn.
Halley’s Comet
A comet which is visible every 74-79 years. It will next be sighted in 2061.

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