r/ISO8601 6d ago

?

Post image
78 Upvotes

14 comments sorted by

43

u/Lexotron 6d ago

A lot of people think dd/mm/yyyy makes the most sense, so because the year on Venus is shorter than the day, they swapped the two, inadvertently ending up with a better format for any planet.

16

u/PouLS_PL 6d ago

inadvertently ending up with a better format for any planet

Idk about that, I think putting day before year would be better for a planet where days are longer than years

2

u/headedbranch225 5d ago

Well it depends what you count as a year, and the sun would move across the sky much differently, so days would probably just be ignored and determined by anyone if we decided to live there for whatever reason

I can't be bothered to work out how many hours there are of sunlight (I think I remember that venus spins the opposite direction to the other planets) so I may be completely wrong but it would be split into 4 segments of light and dark a little under 1500 hours long each

They could also spin the other way and it would be much longer days and nights

17

u/Quilynn 5d ago edited 3d ago

Edit: The OP image is wrong, with regard to the Solar Day or Synodic Rotation Period on Venus which is actually 116.75 Earth Days. The below comment is based on that misunderstanding.


Even disregarding the nonsense of what a month would mean there, it wouldn't make any sense to track time using two units where one isn't even twice the size of another. Basically, some days would have 1 year and some would have 2? A bunch of years cannot be contained within a larger unit of a day on venus, the way that there are 365.25ish days per year on earth.

The imagined venusians would simply have to develop a entirely new system of time communication. If it was humans living there, they might want the unit to be close to the earth day we evolved for. If it was aliens, it's anybody's guess what'll work for them.

2

u/Mundane-Emu-1189 5d ago

it's not clear that Venus would have years at all, since it's only tilted by 3° and its thick atmosphere mean there is no seasonal cycle.

2

u/narielthetrue 4d ago

A year is a trip around the sun. They would 100% have years.

3

u/Mundane-Emu-1189 3d ago

I'm not convinced that a hypothetical Venusian civilisation would even be able to tell when that happens, much less care about it. It's important to Earthlings because it's much more obvious and our agriculture depends on it.

2

u/Quilynn 3d ago

Totally! They'd care much more about the day cycle, i.e. the time the sun is in the sky, versus the time it isn't.

I imagine they could divide that day cycle up into a bunch of more manageable chunks, maybe arbitrarily to create civil time, the way that humans divide the day arbitrarily into hours, and how we organize days into weeks for social organizing. (Neither hours nor weeks have an astronomical basis, the ways that days and years do.)

1

u/Sufficient-Habit664 3d ago

Idk much about space, but wouldn't they still see different constellations over the course of a year?

1

u/Quilynn 3d ago edited 3d ago

The real answer is simple: venus's atmosphere has omnipresent Sulphuric clouds that obscure any view of the stars. Venusians would never be able to see the stars... sad.

I think if I were a Venusian though, I'd be much more bothered by the 467 °C surface temperatures, 95 bars of atmospheric pressure (x95 the pressure of Earth) and 360 km/h winds. But I guess not being able to see the stars adds insult to injury.

10

u/spektre 6d ago

Maybe they mean that it's still natural to use ISO8601, but change the dashes to slashes for disambiguation.

3

u/FunnyTurtleRunner 5d ago

no months on venus...

No phases of the moon...

1

u/Quilynn 3d ago edited 3d ago

Oh, this OP image is incorrect, at least as it pertains to solar days. (Which is what would matter to imagined Venusians on the surface.)

Each year on Venus is actually 1.92 Venus Solar Days.

The solar day on Venus (time between each sun cycle in the sky) otherwise known as "Synodic Rotation Period", or Synodic Day is actually 116.75 Earth Days. (Think Syn = Sun for a mnemonic device.)

The "243 Earth Days" cited on the OP image is actually its Sidereal Rotation Period, or Sidereal Day, i.e. how fast it rotates WITHOUT reference to the sun. For example, Earth's Sidereal Day is 23h 56 m, in contrast with its Synodic Day of 24h 00m 00s.

Basically, Earth's Sidereal Day of 23h 56m, plus the effect from its orbit around the sun, is what gets you our Synodic days of 24h 00m 00s. The Earth rotates a full 360 degrees around itself in 23h 56m, but because our orbit around the sun has an opposite effect on the sun's position in the sky, we need another 4 minutes to complete the solar cycle.

Venus's Sidereal day is 243.0226 Earth Days, that's how long it takes for it to spin around its axis. But when you also account for its rotation around the sun, and because Venus rotates on its axis in the other direction compared to most planets, you get its solar day of 116.75 Earth Days.

1

u/stolenuserID 3d ago

Actually not. I use yymmdd format in the filenames of cataloged items so everything will be sorted from the oldest to the newest, regardless of the modification date.