this post was submitted on 08 Sep 2023
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A day on Venus is longer than a year on Venus. One day takes 243 Earth days, while a year takes 225.
Maybe it's not "well known", but still interesting in my opinion.
I mentioned this one to my friends the other day and it took so much convincing before they actually believed me! Definitely an interesting one. Venus also spins the opposite direction to all the other planets in the solar system, meaning the sun rises in the west and sets in the east.
I get people telling me "no, that's impossible" every time I mention this fact.
"Search your feelings, you know it to be true"
Wouldn't spinning in the opposite direction indicate that it's axial tilt is flipped or something?
The leading theory is a moon sized object hit it with enough force to spin it backwards.
The energy used to reverse the existing motion might explain why it's so slow
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?)
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.
I've seen this fact somewhere before, but I still am unable to grasp it in my mind
Short: It completes a full 360ยฐ of the sun before the planet itself does a full 360ยฐ spin.
A few sentences longer:
In planet Earth human terms, we have defined one day as "how long it takes the planet to do a full 360 degree rotation". Example: You spin a basketball on your finger and it does one full rotation.
A year to us is "how long it takes the planet to go around the sun". Example: You hold a basketball out in front of you and you do one full rotation.
Now, to confuse people further, read about the difference between a solar day and a sidereal day.
How does this affect its gravity?
It doesn't. Gravity is caused by mass not spin. The planet's rotation about it's own axis will create a centrifugal effect that offsets gravity, but the effect is negligible for anything rotating as slow as planets.
Interesting.
It doesn't. Gravity is related to its mass, not it's orbit or rotational velocity.
The others already said the core aspect, but to get specific: the difference between your weight on the pole and your weight on the equator differs only by like .5% or something like that. This is the difference between spinning and not spinning (centrifugal force and no centrifugal force). (And also the difference in radius, since the Earth's rotation makes it a tiny bit flatter than a perfect sphere would be)