Thursday, April 17, 2014

Who Took a Bite off the Moon?

Lunar eclipse, Ames, Iowa (April 15, 2014)

The other night somebody took a bite off the moon, and left it all bloodied and red. According to the Mayas it was a jaguar with its powerful jaws. Seven demons attacking the king, thought the ancient people living in Mesopotamia. Unruly "pets" (lions and snakes) biting their master, the Hupa believed. A sow in ancient Egypt, a three legged toad or a dragon in China, all busy swallowing the moon.

Initially I thought I could just write a post about the intense copper color the moon was sporting during totality, but a short search on google will give you the answer anyway. It is quite simple, in fact: from the surface of the moon during total eclipse, if you look up in the sky you will see Earth's night side, circled by a thin ring of fire as Earth's atmospheres is scattering the light of the Sun behind, the color of sunset. The red color of the "blood moon" is the sum of the light from all sunsets on Earth!

Lunar eclipse are in fact common, and can be predicted quite easily. The ancient Mesopotamians knew enough astronomy to calculate eclipse occurrences with enough advanced time for installing an impersonator for the king, to be attacked by the sky demons. All while the real ruler would lie low hidden amid the populace, waiting for the danger to pass. Columbus himself, it is said to have taken advantage of accurate lunar eclipse predictions to trick Jamaican natives in feeding him and his crew while his ships were being repaired. He just told the natives that his God would show his anger during the night the eclipse was to happen, and obtained new provisions by promising to free the moon on their behalf. If you want to try the same trick with your neighbor, your next chance is on October 8 next fall. It will be visible again from North America, the Pacific, Australia and east Asia. Totality will start at 10:25 UTC (Greenwich time), which is at 5:25AM where I live: kind of early for me... I will probably pass. It will be more convenient in Japan, where it will happen just after sunset, with the red moon rising to the east. Dear japanese friends, six months from now I will be looking forward to admire your photos of the blood moon next to Mount Fuji illuminated by the latest rays of the sunset!

The last photo below shows a wider view with the moon and some assorted companions. The bright star below is Spica, which is a binary system with two massive blue stars that are close enough to deform their shape due to their mutual gravitational attraction. The very luminous spot in the top right corner is instead Mars, which is currently at its closest to Earth, and as such particularly bright. And red too.

The eclipsed moon, Spica, Mars and assorted stars, Ames, Iowa (April 15, 2014)


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