Astronomy Lesson of the Day: Time Zones

just so were clear, I am 8 hours ahead of all of you on the american continent. and this isn't due to hocus pocus, or anything else, but science. astronomy, to be more precise.
Rarotonga was appropriated a wonky time zone for politics. that's different.

how is paris today?
rainier, but not as cold
today was a nice day
tonight it's FREEZING
i am 8 hours in the future
what a weird idea. time difference.
i bet it's cold. brrr
it's cold here and i imagine it's comparably colder where you is
why is that weird?
according to the earth, my day started before yours
not that much colder,bout the same.
winter in france is much like bc
it's just a funny thought. i like time differences. it's like sci-fi, and it seems pretty arbitrary.
it's not arbitrary! it's science! astronomy!
it's not scientific. rarotonga is two hours behind bc but like 10x further away than saskatchewan, which is two hours ahead.


Veronicahhh in Paris says:
hey- the fact that i am 8 hours ahead, that is all due to astronomy and the earth and sunrise, right?
Jon - almost... says:
Jon - almost... says:
sidereal days and whatnot
Veronicahhh in Paris says:
can you briefly explain that whole mecanism to me
Jon - almost... says:
Jon - almost... says:
k so
Jon - almost... says:
first just start imagining the earth rotating, but without the whole orbit thing
Jon - almost... says:
so a 24hr day is when any point on the equator gets back to straight at the sun
Veronicahhh in Paris says:
keep going, it's going to be published
Veronicahhh in Paris says:
michelle thinks it's all hocus pocus
Jon - almost... says:
k well its real
Jon - almost... says:
so the clock is roughly based on position of the sun, so at noon, the sun is directly overhead
Jon - almost... says:
but 1/4 way around the equator, it is either sunrise or sunset
Jon - almost... says:
now you have to factor in the planets orbit....
Jon - almost... says:
now... if you imagine the same thing that you did before, the planet rotating until a point hits the same spot
Jon - almost... says:
but now move it slightly around the orbit
Jon - almost... says:
that same line actually has to turn slightly more than 360deg to point back at the sun
Jon - almost... says:
thus it is 365.4 or whatever days, instead of an even 360
Jon - almost... says:
therefore... we actually measure the year by the sidereal year, which is , you know how the planet is actually slightly off axis, we measure it by when the axis comes back to flat
Jon - almost... says:
Jon - almost... says:
thats your astro lesson today


Ian said...


Ish said...

Ha. It may be real but it's still based on silliness. I point you to Newfoundland's 1/2 hour time zone and the way in which the international date line snakes around the Pacific:

love love

vaughn said...

I'm gonna make Jon explain that to me again.