Today I Learned

It kinda depends how you define "a day". The usual standard colloquial definition we use would be a "solar day", i.e. how long it takes for it to go dark and light once each, i.e. noon to noon.

The definition you're using in this post though is a "sidereal day", which if you just say "a day" no one would mean, thus this post is misleading. A sidereal day is how long a planet needs to spin around itself.

A Venus "solar (normal) day" (like we normally use the phrase "day") is 116.75 earth days, while a Venus year is 224.7 earth days. The "sidereal day" that you're talking about here is 243 earth days long. So a day on Venus is actually shorter than a year on Venus, at least if you use our usual definition of "day".

Since Venus itself spins opposite to its orbit around the sun, its own spin together with its orbiting around the sun add up together to make the "solar (normal) day" shorter.

An Earth sidereal day is 23 hours 56 minutes while its solar day is 24 hours long. Here, the sidereal day is shorter than the solar day, because the Earth spins in the same direction as its orbit.

Sources: [1] [2]

My son went back to college in his late 20s to get a degree that might lead to a job, so he was in class with a lot of 18 year olds.

He had a astrophysics class, and got in an argument with a girl who insisted that the Sun went around the Earth. He asked her how the length of a year was measured, and she said that long, long ago, some guys just chose an arbitrary number of days to make a year.

the datetime library developer takes another bottle from the liquor cabinet

Hey OP! I'd rather spend a day with you than on Venus!

I love how much of a rebel non-conformist Venus is. Years longer than its days, rotates the opposite direction than all other planets because fuck you, thats why. And don't you even THINK about getting close and trying to land on her. Just ask the Russians how that went. You can't handle her pressure, temperature nor toxic atmosphere. What a bad bitch. She doesn't need nor ask your permission to do jack shit.

One is rotation, but the other is revolution.

Rotation: circular motion of a body about its own axis.

Revolution: motion of an object moving around another object.

Wow that is incredible. Isn’t Venus year equal to 200 or so Earth Days?

Imagine there's a leap year and suddenly the year is three times as long

I think my physics teacher told me this fact but followed it up with "Measuring a planet's rotation around the sun by how fast it rotates around it's center is like trying to measure the speed of a truck based on how many rotations a ballerina can spin inside of it."

That quote haunts me.

This one fact always blows my mind.

Are we talking sidereal day or solar day? Both?

quality TIL post. we didn’t know this either!