
What Time Is It on the International Space Station? (2013) - vinnyglennon
http://www.astronautabby.com/the-international-space-station-time/
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aynsof
It's weird that the author chooses Iceland as an example of a GMT+0 country,
rather than Britain which is where Greenwich is.

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admp
Unlike Britain, Iceland does not have Daylight Saving Time, and therefore is
GMT+0 throughout the year.

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Pxtl
Am I the only programmer who is suddenly super duper envious of Iceland?

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ygra
DST should not be the only reason to use UTC. It's probably just what makes it
obvious once a year that someone uses timestamps wrong.

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clamprecht
I think they actually have a separate time called OBT (maybe it stands for
Orbit).

I was at the Johnson Space Center in Houston recently, where we got a tour of
the live Mission Control room for the International Space Station. I noticed
two clocks at the top of one of the screens. One was GMT, the other was "OBT",
and the OBT clock was around 17 seconds ahead of GMT. I think it has to do
with relativity, and the fact that the space station is moving relatively
faster than the earth. Maybe someone can confirm.

I got a photo of this mission control monitor if anyone is interested.

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jharohit
If you know the clock drift, won't you be able to calibrate the space station
clock back to GMT+0, thus eliminating the need for an OBT?

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dannyw
GMT is already corrected back to earth GMT. But if you’re doing a time
sensitive measurement and went to measure real seconds, you look at OBT.

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sxcurry
Technically, UTC is a time standard, and GMT is a time zone, so the two,
although equal, are not really the same thing. Also, you can set your iPhone
to UTC in the World Clock, which I do as an amateur astronomer.

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rocqua
I thought UTC the same, doesn't that mean that GMT+0 is essentially wrong? I
thought GMT was essentially UTC+0, and all other time zones (ignoring DST) are
defined as offsets to UTC, not GMT.

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thomastjeffery
Think of it as two pointers referencing the same data:

    
    
        Time* UTC = Time(0);
        Time* GMT = *UTC;
    
        *UTC == *GMT; // True
        UTC == GMT; // False

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TheSoftwareGuy
Your example with pointers actually wouldn't compile, and I think the analogy
you are trying to make is not accurate. On the second line you are assigning
the target _address_ of `GMT` to be the _value_ pointed to by UTC. In other
words you are trying to assign a value of type "Time" to an object to type
"Pointer-to-Time".

If, however you meant for that line to be: Time *GMT = UTC;

it would compile fine, but then your second comparison would evaluate to true,
and the whole analogy be rather pointless.

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thomastjeffery
What I meant was to have them both point to the same data, but be different
objects.

Sure, C wouldn't work that way, but it's just supposed to be pseudocode
anyway.

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truculation
Tom Scott on timezones:

[https://www.youtube.com/watch?v=-5wpm-
gesOY](https://www.youtube.com/watch?v=-5wpm-gesOY)

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JazzProgrammer
We spent a lot of time at Yeshiva discussing when a Jew in space, or on Mars,
or on a planet orbiting Alpha Centauri (for example) would have to light
Shabbos candles or celebrate Yom Kippur.

This issue has already come up with Jewish astronauts on the Space Station.

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d33
...is it even allowed to set things on fire inside of ISS?

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peeters
This kind of makes me want to make a site that will show the current solar
time of the ISS. i.e. when the ISS is between the Earth and Sun it's 12:00, on
the opposite side it's midnight. And show what time sunrise and sunset are.
The minutes would obviously be much shorter (as a day is only ~90 minutes
long), but it'd be interesting to see.

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dfox
I find it somewhat interesting that when SpaceX's streams switch to views with
burned-in timecode it is always in UTC.

Edit: and usually in ISO8601-ish format

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rocqua
If you are going to design something using a time code the most obvious
solution is probably to choose your own zone. When you realize that doesn't
apply to anyone else, UTC is the next option. Especially because it means you
don't need to deal with user configuration.

As for ISO8601, that probably results from people looking for some standard to
help with compatibility. If you just mean YYYY-DD-MM HH:MM that is just nicely
ordered. Actual ISO8601 would yield something like: 2018-03-11T22:53:40+00:00
I personally really hate that T in ISO8601, but it is actually a standard
aimed at being both human and machine readable.

All that aside, I think we can all agree that MM-DD-YYYY is just incongruous
and stupid.

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philliphaydon
It’s yyyy-mm-dd not yyyy-dd-mm....

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rocqua
You are totally right, I got that wrong :( sadly it's to late to either edit
or delete my shame.

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saagarjha
> Unfortunately the built-in iPhone clock application does not recognize the
> International Space Station in its search.

But it _does_ do UTC.

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rocky1138
Do their clocks take into account time dilation?

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prepend
Article claims that Houston is GMT-5, but isn’t Houston GMT-6 as part of
central standard time? (Although not CDT is GMT-5).

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United857
It's not just the ISS -- GMT (aka Zulu) is the standard for aviation and the
US military in general.

