h a l f b a k e r yAlas, poor spelling!
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A clock to mimick a normal office clock, but
with a little wheel in the back that lets
astronomy-interested owner adjust the length
of a 24-hour day to match the actual speed of
some other planet's rotation.
Prague Town Hall clock.
http://www.discover...e/oldtownhall_v.jpg
A really cool 600 year old clock... [StarChaser, Sep 15 1999]
(??) More information on it.
http://otokar.troja.../RelatGrp/Orloj.htm
More in-depth info, including that it was burned down by the Nazis in WW2. [StarChaser, Sep 15 1999]
Martian analemma
http://apod.nasa.gov/apod/ap061230.html
From Sagan Memorial Station [lurch, Apr 11 2011]
[link]
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Thanks to the commentators that have helped me
progress from medieval to rennaissance
models of planetary
motion. Obviously, (1) astronomy needs to become
a school subject and (2) I shouldn't be involved
in setting the curriculum... |
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Reportedly, during the Mars Pathfinder
mission, a number of JPL operations techs
started sleeping on Mars time so they'd
be awake when the (solar-powered) lander
was active. |
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Since (as far as I know) this idea hasn't
come to pass yet, I presume they used
computer programs and Mars/Earth time tables. |
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In a similar vein, there are clocks available that run on what astronomers call sidereal time. This is the time it takes for an object to return to the same apparent position in the sky (off-setting the Earth's movement around the sun) |
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In a different artery, has anyone seen the 'astronomical clock' in the city of Prague? I'd love to have a screensaver of that thing that kept time... |
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It'd be really cool if it was three dimensional with all sorts of orbit gizmos and such. |
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I knew these guys who decided to go onto a 10 hour day to be more in tune with the metric system. They would sleep from hours 9-1, eat at a certain hour, etc. regardless of when that occured in the real world. Needless to say, they didn't attend too many of their classes, and failed out of school, but hey, it was pretty funny. |
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The French tried to do a metric clock after the revolution...it bombed too. |
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[salmon]: That's called an
"orrery", and they do exist. |
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[MuddDog], [StarChaser]: We have
metric calendar ideas in plenty...
isn't there a metric time idea
floating around here somewhere? |
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2011: More info link from 1999 is dead now. |
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I think if this was for sale on Firebox I'd buy one. |
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I also think that, as with all things from Firebox, its
fascination would last for a few [Earth] days. (I collect
watches, and love my 24hr watches because they're a bit
odd. But, strangely, I never find myself wearing any of
them.) |
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(Actually, truth be told, I never wear a watch anyway.) |
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If you want to make this really geeky, have one clock hand for each planet EXCEPT Earth. To figure out the Earth time, you'd have to really keep track of where we are relative to everyone else. |
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There's a problem with this, maybe. |
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Time depends on where you are on the planet, and also on
where the equivalent of the Greenwich Meridian is defined. |
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For instance, what time is it on Venus right now? |
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Venus has a prime meridian as do Mars and Mercury, so there
should be no problem setting this watch. With gas giants,
it's a little more difficult, but Jupiter apparently has
something called Central Meridian Longitude which is a line
of longitude defined by a particular time, rather than vice
versa. Time still depends on where you are on the planet,
but in that respect, this watch is no more problematic than
any other. |
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The real problem is what to do about Daylight Saving Time. |
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Venus Standard would be the time at the meridian through the central peak of the crater Ariadne. |
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Mars Prime Time would be local at the crater Airy-0. |
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But, yeah, let's go ahead and get started on the Daylight Savings Time thing for Mars - the equation of time over the course of a year runs from about -50 minutes to +40. Some adjusting might be handy. |
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Would you assume you're at the same longitude on Mars as
you are on Earth? |
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[MB] Well, I see what you mean, but that's precisely as
much, or as little of an issue with a Venus clock as with a
conventional Earth clock. The worst you can say is that
the Venus clock is unlikely to be useful, since you're
unlikely to be on Venus. |
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But clocks* are commonly set to a location different from
the one where they're located. The proposal would be a
splendid addition to the display in an airport or train
station, with half a dozen clocks showing time in different
cities. Alongside "GMT," "New York," "London", "Moscow,"
"Tokyo," would be "Venus (Ariadne Crater)" or "Mars (MPT)"
You can't say that wouldn't be cool. |
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*The proposal's for a clock, not a watch, contra my error
above. But even watches are sometimes set to elsewhere-
time. |
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//Would you assume you're at...// some point of interest, I presume. |
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I would, personally, set my clock to AMT-04:45 (AMT=Airy Mean Time) to correspond to the location of my selected homestead in Kasei Vallis. It's a real geek-deflating moment to have somebody ask what your time-mark points to, and have to answer "dunno". (The Opportunity rover is only about -22 minutes local solar from AMT(although the team uses -1:01:06; they offset for the equation-of-time at a point halfway through the (90 day!) mission(bwahahaha!))) |
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