Everything There Is To Say About Eclipses


Eclipses are an amazing phenomenon. There’s almost nothing else that can unite so much of the planet with an overcast day. Eclipses happen pretty near any time something gets in the way of something else. The Moon gets in the way of the Sun. The Earth gets in the way of the Moon. Jupiter gets in the way of Venus. Venus emits a elaborate string of subtweets. Triton, misunderstanding, gets hopping mad. The Trojan asteroids, who find angry Triton the funnies Triton, stir things up. Before you know it there’s a rain of meteors being sent every which way. This is why we try not to have Jupiter eclipse Venus anymore. We’ll just stick with the two biggest eclipses, solar and lunar. People wanting more exotic stuff can fundraise for it themselves.

A solar eclipse is when the Moon gets between the Earth and the Sun. This means that large portions of the Earth aren’t being pushed away from the sun by the pressure of sunlight anymore. However, the Sun’s gravity remains exactly the same. This means that the surface of the Earth underneath the eclipse drops towards the Sun more than it usually does. This is usually not a problem. If it starts to be one, we take care of it using leap seconds. During a leap second everyone on the affected hemisphere is supposed to get up on top of their tallest chair and leap to the ground simultaneously. Shame on you if you haven’t been doing your part. You can make up for it during a skip minute. These are rare than leap seconds, but run longer, and involve more skipping.

Each year the Earth experiences at least two but not more than 110,575 solar eclipses. You’d think we could narrow that range down a little. It’s hard. There’s a lot of mathematics involved figuring out eclipses. Be kind to the eclipses. It’s not like eclipses are the only things in our life trying to understand what they’re doing.

Still, there are only a finite number of eclipses each calendar year. Use them wisely. Any given spot on Earth can expect to see only one-370th of an eclipse per year, too. This explains those weird moments when it’s the middle of a bright day, then it gets dark a second, and then it’s bright again. No, different from how it looks when you blink. This is more when it looks like you’re worried someone went and broke the sun again.

This highlights one of the major uses of eclipses. During the Apollo-Soyuz Test Project back in 1975 the astronauts and cosmonauts and testtronauts actually created an artificial solar eclipse. They used this to switch out the Sun with a new fluorescent-based lighting fixture. It promised to save incredible amounts of energy, important during the oil shortages of that decade. So much so that it was even worth leaving the Sun on all night. But there were problems, of course. For one, people insisted they heard this irritating buzzing. And this even from people who insist they can hear it when old-style computer monitors are turned on, even when you know the computer monitor was turned off.

The more serious problem is what it did to colors. With the alternate light spectrum, you had to change the way you did colors, and that’s why the late 70s looked like that. We were doing our best under weird circumstances, which again, you are too. But the original Sun, which had been put back in its wrapper and was in great shape after some time off, was replaced during the STS-9 space shuttle mission. People got their first look at what colors they had been using the past eight years and there was a lot of screaming. Again, different from how we’re screaming these days. And anyway then we went on to produce the fashions of the mid-80s anyway.

There are no plans to tinker with the Sun during any of this year’s solar eclipses. But do remember, one of the other major uses of solar eclipses is by desperately unprepared time-travellers who hope to set themselves up as wizards or gods to unsuspecting peoples. If you spot anyone promising to make the Sun go away if their friend isn’t released soon, be wary! They might not return the Sun and we’re still using it sometimes.

What is the Draconitic Cycle?


In my reading I just came across a mention that the moon has something called the draconitic cycle, or sometimes, the draconitic period (or “draconic” if someone is getting all tense about “draconitic” as a word). The term is a bit of a holdover from medieval astronomy, when everybody was worried all the time that an eclipse might sneak up on them, and so you can see the use in a term which represents how long it takes between successive passages of the moon through its ascending node. Really, it’s amazing they thought they needed to name that at all; surely the idea of successive passages through the ascending node is so common that it barely needs a word, the way we express such concepts as “       ” or “      ” or even “        ” by leaving a gap hanging in our conversations and just waving our arms frantically at people who don’t know what we’re going on about. Anyway, it picked up the name “draonitic cycle” just as you might expect, by astronomers watching the skies night after night to see how long it takes the Moon to be run over by a bicycle, which took until about 1890. Before then bicycles were just those hilarious things with a giant front wheel and a tiny back one that you could ride for parts of a second before tipping over and falling down. The cycles are much quicker these days.