this post was submitted on 16 Apr 2025
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Showerthoughts
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A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. The most popular seem to be lighthearted clever little truths, hidden in daily life.
Here are some examples to inspire your own showerthoughts:
- Both “200” and “160” are 2 minutes in microwave math
- When you’re a kid, you don’t realize you’re also watching your mom and dad grow up.
- More dreams have been destroyed by alarm clocks than anything else
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But is there a time that the ISS is moving in the same direction as the earth for <=134,600 km/h?
That is a situation I had not considered.
Viewed from above the north pole, the planet's rotation, orbit and the ISS's orbit are all moving in a counterclockwise direction. The ISS's orbit is inclined ~51° from the Earth's rotation, and the Earth's rotation is tilted ~23° from its orbital plane.
I think that means that Earth & the ISS never have their orbits perfectly aligned, but for our purposes that doesn't matter. All we need is for one moment in time, for the ISS's vector to line up with the Earth's, and we should get very close to that at two times of the year, where the ISS's ~~northernmost or southernmost parts of its orbit fall on the farthest point of its orbit away from the Sun. This should be true regardless of Earth's tilt at that moment.~~
( edit: on reflection, not quite true, you need the ISS's highest or lowest point relative to the plane of Earth's orbit, but it will still happen twice per year )
At those moments, the ISS is travelling with the direction of the planet, very close to parallel, and its speed relative to the Sun should approach ~134,600 km/h, unless you did the math wrong, I didn't check that.
In this same orbit the ISS should also reach its slowest point, as the opposite side of its orbit should be aligned against Earth's orbit.
But also, in the premise of this idea is the admission that the bicycle is "stationary", because its speed in relation to its immediate environment is what matters, and we all know it.