short takes

[cellio]

Serendipity (definition by example): receiving an invitation for Shabbat dinner from someone who's been trying to invite us for a while, on a night when my dinner plans are easily aborted and the service I'll miss as a result is being led by one of the grade-school classes. That's a no-brainer. :-) (And Dani agreed to go.)

I haven't been paying a lot of attention -- I prefer my experience of sunrise to be theoretical rather than actual -- but I was under the impression that the equinoxes (you know, "equal night/day") canonically fall on the 21st of March and September, with about a day of wiggle room to either side depending on circumstance. But according to daily sunrise/sunset records, the vernal equinox this year appears to have fallen on March 16th or 17th. Tomorrow, the 20th, will have 12 hours and 10 minutes of daylight. Huh? (I'm looking at Pittsburgh times, but since we only care about deltas that shouldn't be important.)

src has been going through hell at work, but this account had me laughing for quite a while. We have given up trying to recreate the gleaming marble edifices which were extant when we last left these boxen, before "oh, so-and-so was working on this console a few hours ago, I wonder if he...". We will settle for sturdy, habitable brownstones. (There's funnier stuff near the end that I don't want to spoil.)

Link from siderea: We See That Now - a heartfelt -- no -- abject -- no -- craven apology to the right from the left for our campaign of hate, anger and malice against God's own president.

VAXen, My Children, Just Don't Belong In Some Places -- an old favorite from Usenet; link courtesy of dglenn.

Comments

[dvarin.livejournal.com]

Due to refraction of light as it enters the atmosphere, the sun rises a little earlier and sets a little later than might be expected just by calculating when the physical star comes above the plane of the horizon.

Also, it depends on when "sunrise" is--I wouldn't be surprised to learn that on the equinoxes the center of the sun passes the horizon exactly 12 hours from when it last passed, but that means that the leading or trailing edge will cause daytime to start earlier and end later than that, and probably the "sunrise" and "sunset" times are the passing of the edge of the sun over the horizon rather than the center.

Close but no cigar...

[caryabend.livejournal.com]

If I recall my Astronomy 101, an equinox occurs when the sun's center crosses the celestial equator. So your explanation of the length of day and night is essentially correct.

[cellio]

Thanks (and thanks to Cary too). That makes a lot of sense.

[moose]

"Vaxen, My Children, Don't Belong Some Places" and other fun hits of the early computer folklore days, including the infamous "racing disc drives" and "Robin Hood & Friar Tuck":
http://www.psc.edu/~ecf/comp.folklore.html

Note, at the bottom, that "Vaxen, My Children" was originally posted on a DECUS bboard in 1989. The original writer contacted me last year.

[cellio]

Wow, thanks! Some of this is a nice trip down memory lane, but most of it either is new to me or had completely faded from memory.

[siderea]

Oh, good gracious, the Vaxen story was a riot.

[juuro.livejournal.com]

As has already been mentioned, despite the name, equinox is not defined by equal length of night and day. That is only an approximation that will hold for some tropical latitudes when the accuracy of measurement of time is that of a poor clepsydra. The actual equinox agrees with your impression, and is defined by sun crossing the equator.

See also http://www.livejournal.com/users/juuro/96122.html

[cellio]

Thanks for this! I enjoyed reading your entry.