this post was submitted on 08 Sep 2023
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Ok hold up so the way I'm understanding this is that its tilt (day) is slower than it's rotation around the sun (year). Is that right or am I way off?
Yep, and as a result, the 'movement' of the sun across the Venusian sky during a day seems to change direction (I think?)
You're close. Not the tilt of its axis, but its rotation around its axis (day) is slower than its rotation around the sun (year).
Earth's axis is tilted at about 23 degrees, which causes the seasons. Venus, by contrast, is tilted only about 2.6 degrees, and thus basically doesn't have seasons in a comparable way.
Earth's axis does very slowly wobble around (precession). Over long enough time scales, this affects the seasons, and it means the North Star has not always been aligned with Earth's North - once, North pointed at a patch of black sky and the North Star was just another star appearing to rotate around that arbitrary point.
I'd imagine Venus's axis might also wobble at least somewhat, but I haven't actually looked into this at all.
Thinking about this sent me down a rabbit hole because the day and year lengths are so extremely close to each other, and Venus rotates around its axis clockwise (unlike the other planets) while spinning around the sun clockwise, and its tilt is so slight... so as it spins around the sun, it rotates just enough to keep one side facing the sun almost all the time. I ended up googling whether it was tidally locked, like the moon is to Earth (such that we only ever see one side and it never changes) - and apparently it would be, but its atmosphere is so wild that it prevents tidal locking. But it almost is. It kinda has a dark side, and a light side, like the moon, but there's just enough mismatch between the yearly rotation the axial rotation that the side facing the sun changes slowly. This is the first article I found.
From that article, it seems like the daylight hours you'd experience standing on the surface of Venus would be 117 Earth days of light, before it got dark again. So the sun would rise, and then you'd have about half a Venus year (aka about half a Venus day, too) of daylight before you'd see night again. And then it'd be night for the rest of the year. But still scorching hot because atmosphere.
Anyway this is blowing my mind a bit. I feel like I should have known this - I used to be obsessed with astronomy when I was little. Maybe I knew it once and forgot. I don't know. But dayum. Planets are cool.
Yeah the Venus makes a lap around the sun in less time than it does a rotation around itself relative to said sun's position in its sky.