Posts Tagged ‘Astronomy

22
Jun
07

Solstice

Today is the first day of summer, the longest day of the year, but you’d hardly know it. It doesn’t feel much like summer. New York has been blessed with a mild spring this year. I desperately hope the lower temperatures continue.

It is the summer solstice. Basically, it all has to do with the position of the sun — which is way over my head. And everyone else’s too. (Heh heh… get it?) Twice a year, the sun’s path around the earth is the farthest north or south it can get from the Equator. On June 21, the North Pole is tilted toward the sun. Six months hence, on the winter solstice (to us Northern Hemisphere folk), the South Pole will be tilted toward the Sun. On the first day of summer, everywhere north of the Arctic Circle has 24 hours of sunlight, and the length of day at all places north of the Equator is more than 12 hours.

It amazes me to think how much of human belief has been shaped by the length of a day. It’s all down to the accidental 23.45° tilt of Earth’s axis, and its distance from the sun. One or two degrees in either direction, and the whole of human existence could have developed completely differently.

Who knows: If we were tilted a bit further, the polar ice caps would be bigger, we’d all be a little cooler year-round, sleep patterns would be different, biological rhythms would all be different.

We seem to make a bigger fuss over marking the winter solstice. Winter celebrations predate agriculture. As winter approached and the days grew shorter and the temperature dropped, and plants, animals and people began to die all around, I can see how ancient people might have been afraid that the sun was disappearing and not coming back. I’d do whatever I could do to get it to come back. Apparently, they lit bonfires and had big parties and built religions. (Today, rather than lighting bonfires, we risk housefires and death by electrifying evergreen shrubbery.) This in turn led to the founding of civilizations and nations and economic systems and flying to the moon and realizing that the whole thing is actually not managed by a guy in a glowing horse-drawn carriage.

My hat’s off to those weirdos who counted the as-yet-undefined units of time between sunrise and sunset, and to all those who broke their backs hauling enormous stones and such just to tell time and mark dates. It’s so easy for us now that they’ve done all the work.

22
Mar
07

Equinox

Today was the first full day of spring. It’s the vernal equinox — in the northern hemisphere, at least.

The word “equinox” reminds me of two things. The first is my birthday, because it falls around, and sometimes smack dab on, the autumnal equinox, six months opposite the vernal.

Equinox    
Galileo was close.
[nasa.gov]

The second is Matthew Modine, because he was in a movie called Equinox in the mid-’90s, which I never saw. I had a big crush on him as a lad. Oh, how I loved to watch him jump rope in Vision Quest. As a kid I found those one-piece wrestler get-ups to be pretty … evocative.

Technically, the equinox is one of two times during the year when day and night are the same length all over because the sun is directly above the equator. You can read more about it and find head-aching terms like “ecliptic equator” and “celestial equator.” All it really means is that we now have a reason to be impatient with the weather for every day we go lower than 60° F. It’s spring, dammit!

I wonder what you would see at the poles on the equinox. Twenty-four hours of sunset?

Pretty close, according to what I read on Wikipedia, which I have no reason at present to doubt. As far as I can figure, we’d see 24 hours of just-before-sunset. These astro-mathematical models work for perfect spheres with no atmosphere in cold, empty space. But real life isn’t so simple. Apparently, day is always longer than night. Because the sun is a huge ball of fire in space, not a single point, when it sinks halfway down past the horizon it’s still day time. Also, because the atmosphere refracts light, it will actually bend the sun’s rays around the curvature of the earth, which is why you can still see for a few minutes after the sun sets.

It’s a good thing the poles aren’t so hospitable to humans, or we’d have a heck of a time getting to work on time.

24
Aug
06

Good-Bye, Pluto!

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Pluto and Charon skulk off to a dark corner of the solar system to pout about their demotion. Charon has reportedly threatened to “kick Earth’s ass.”
[Gene Smith’s Astronomy Tutorial]

I never learned the mnemonic device to remember the order of the planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. I remember the lines of the treble clef scale are the notes E, G, B, D and F, because Every Good Boy Deserves Fudge, but I was never aware that My Very Excellent Mother Just Sent Us Nine Pizzas.

And it’s a good thing, too. I might have wasted a lot of time memorizing this, because it’s all quite useless now!

Dictionary researchers might all now breathe a sigh of relief, but sentimentalists are already having a hard time adjusting to the new order. Because we finally have a workable definition for “planet,” some scientists meeting in Prague have decided to strip Pluto of its planetary status. Pluto and its primary satellite Charon are now “dwarf planets.” I think they’re calling these itty-bitty planetoids “plutons,” in honor of the recently defrocked rock. You know, a consolation prize. No one goes home empty-handed!

Ah, Pluto, you’ve been a good sport all these years. Thanks for playing.

Early reports indicate that Pluto is coping well with the news. “It’s not what we were hoping for, obviously,” the stunned celestial body said, “but life goes on. We’ll get through it all right. I just want to be with my family now.”

The move means a considerably greater loss to Charon, which has less graciously accepted the news. Charon is only a satellite, and now it’s not even the satellite of a planet. Charon, loyal to Pluto to the bitter end, has retracted earlier threats that it would “kick Earth’s ass.”

“It was said in the heat of the moment. I’m sorry. At least I’m not a lousy moon, I guess,” Charon said. “But what am I?”

No longer can our very excellent mother send us pizzas. Now she must instead send us none. Or nowhere. Or maybe noodles. Because Neptune is now officially the furthest planet from the sun in our solar system.

Apparently we were laboring without a definition of “planet” all this time. I don’t remember having any difficulty with the subject in elementary science classes. In fact, I’m sure I’ve taken tests that contained questions assuming a definition the word. Hey — I want those tests re-audited! This may affect my academic performance in retrospect all the way up through college admission. Maybe I could have gotten into an ivy league school. I’ll sue!

Truly, I don’t understand what the fuss is about. This is not a surprise. Pluto doesn’t care. It’s unlikely that there are any life forms on the pla— oops, dwarf planet — who would care, as Pluto only has an atmosphere for 20 years every 248 years. It’s still out there, happily, ignorantly dancing with Charon, waving to us — “Don’t forget about me, schoolchildren of Earth! You haven’t seen the last of me yet!”




the untallied hours

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