A once-in-several-lifetime event is happening tonight- The full moon will pass into the shadow of the earth on the shortest day of the year, resulting in a total lunar eclipse that will be visible to all of North America. The last time this particular arrangement occurred was 456 years ago, so tonight is a night to party like it’s 1554! The action will start around 11:30 tonight (mountain standard time), with the glorious red totality occurring by 1:30 AM.
For the curious, there is lots of cool stuff that’s associated with both eclipses and solstices. The planets all rotate on the same plane, because they all formed from the same rotating disc of baby planet stuff. The moon came later, resulting from the collision of a Mars sized planetoid bashing into the earth, so the orbit of the moon isn’t on the same plane as the ecliptic.
The solstice is when the sun is at it’s lowest in the sky, which occurs because our planet rotates at a tilt with respect to the ecliptic plane. In addition to this tilty business, the shape of the earth’s path around the sun is slightly oval, so on December 21st, the earth is actually closer to the sun around this time of the year, where it is about 5 million kilometers closer than at the peak of summer. It’s counterintuitive that we’re closer to the sun when it’s so damn cold in the northern hemisphere, but it just heightens the importance of the axial tilt in determining our seasons.
The Solstice is also the date of another cosmic alignment- between the earth, sun and the centre of the milky way. This is a pure coincidence, although those disingenuous conspiracy mongers behind the 2012 fallacy, along with any astrologers, will claim that this has ‘special significance’. For the record, the galactic alignment happens every year without anything particularly interesting happening, so those guys are obviously full of shit. Still, this year will have the sun, earth, moon and galactic center in a straight line, which is pretty cool, but meaningless.
As for why the moon will be red during totality, this is because the suns light diffracts through the atmosphere- think the redness in sunsets and sunrise. If you were standing on the moon during the eclipse, you would be seeing every sunrise and sunset on the entire planet simultaneously , which is also awesome.
Events like the eclipse today always remind me of the insanely awesomeness of reality. We’re little specks on a bigger speck, hurtling at thousands of kilometers a second endlessly around a thermonuclear furnace that sustains all life, which itself is one of hundreds of billions of similar stars in one mind-boggingly massive galaxy, which is just one of countless other galaxies. We are made from the dust of exploded stars, but uniquely (as far as we know), these particular arrangements of stardust can look up at the endless cosmic dance and understand. Cultures all about the world have celebrated both the eclipse and the solstice in their own way for millennia, creating traditions and stories that define us. I find this resonance of astronomical events with the fabric of human experience to be deeply satisfying, which is why I’ll be watching the eclipse and celebrating the connection between myself, humanity, and the cosmos that we all share.