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Wednesday, May 19th, 2004

Time Event
You are my sunshine

I learned who won the faculty best-teacher award that I wasn't nominated for. As it happens, it was one of the handful of people I've been instructed by; if the seminar of his I attended last year explaining the analemma was a reliable sample, he is one of the best instructors I've ever seen. It's tricky judging how good an instructor someone is from a seminar, though -- they tend to be about things the speaker is enthusiastic about, and that energy shows. Look at the listless way any instructor who's had the same class six years in a row attacks the material. The first time through the instructor usually doesn't know what the focuses of the course should be; the second and third times are typically best. After that, if there's no break, burnout tends to set in. But he's interested in the analemma and his talk about it was great.

The analemma is the difference between ``mean sun time'' -- what the time would be if the sun took exactly 24 hours from one noon to the next, what you get from a watch -- and ``local sun time'' -- time based on where the sun actually is, what you get from a sundial. If you take a picture of the sky from the same base at (say) 10 a.m. Standard Time every day for a year, the sun traces out a figure eight as it gets ahead, falls behind, gets ahead, and falls behind of the ``mean sun''. That figure eight's the analemma, and it's most often seen in the middle South Pacific on maps and globes whose makers feel awkward leaving that much empty blue uninterrupted.

Can you spin that out to an hourlong interesting talk? Yes, if you're good, and he is. It helps to have surprises to deliver, and there are several that follow the analemma. For example, from Singapore's latitude the variations in the length of the day are dominated not by which hemisphere tilts toward the sun (as they are in the United States and western Europe) but by the fact the Earth moves faster in January (when it's nearest the sun) than it does in July (when it's farthest).

Other compelling trivia: the earliest sunrise in Singapore is around 1 November and the latest sunset is around 10 February. The dates of earliest (and latest) sunrise and sunset depend on latitude, of course; the fascinating thing is they depend roughly continuously on latitude -- make a small change in latitude, see a small change in the date -- until you reach about five degrees north (or south) latitude. Then suddenly earliest sunrise jumps to May or June. Similarly the day of latest sunset is around 9 February until one reaches about three degrees north or south latitude; then it jumps to mid-July. (Latest sunrise and earliest sunset also vary, but not so dramatically.) These are all effects of the analemma and the equation of time, and if you can find wonder in that, congratulations; you are part of the circus of Doctor Lao.

In other news, the BBC report that the GoFast rocket of the Civilian Space eXploration Team is believed to have reached 100 kilometers in altitude -- accepted by most everyone but the United States government as ``the border of outer space''. (They're waiting to decipher flight recorder data, thus the ``believed to have reached'' wording.) Matching this with Bert Rutan's SpaceShip One's reaching 64 kilometers with pilot Mike Melvil and it looks like 2004 could be a very good year in space indeed.

And I understand Rick Berman believes he's working on what may become the eleventh Star Trek movie. Isn't he cute when he carries on like that?

Trivia: As a child Peter Ustinov pretended he was a motorcar long enough to worry his parents. His grandfather assured them his incessant motor noises were just the sound of his imagination developing. Source: Dear Me, Peter Ustinov.

Currently Reading: The Map That Changed The World, Simon Winchester. (Hi yellow3!)

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