Imagine holding a ball at arm's length and rotating it so slowly it would take 24 hours to rotate it. That's really slow, right? That's what the photo from space looks like.

It only sounds fast when we hear it in everyday units like miles per hour because the earth is really big.

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OP would love night sky timelapse videos or long exposure photos, really shows how quickly things do move even tho its barely noticeable from where we are

Yep, this is the answer, pretty much. I think all misconceptions with Earth and space are directly linked to misconceptions of scale and size ratio.

It takes 24 hours for the earth to make one rotation on its axis- it's roughly 1000MPH. If you were to sit in the exact same spot in space for say, 6 hours, you would be able to observe the Earth make a quarter rotation - about 6250 miles.

For contrast, NY to Hawaii is about 5000 miles. Beijing in Eastern China to Istanbul in Western Turkey is about 7000 miles. You would be able to notice the change, but six hours is a long time to observe for, so you may not really perceive it.

Earth rotates fast in the sense that the linear speed of the rotation at the equator is fast. It does not rotate fast in the sense that it makes a full spin quickly (it doesn't; it makes a full spin in - from a distant perspective - 23 hours and 56 minutes).

If you were floating just above the equator and not co-rotating with the Earth, you would see the land below you flying by at an extremely fast pace (about 1.5x the speed of sound). But if you're in space, you're quite far from the surface of the Earth - at least a hundred miles or so - so that speed doesn't look too too fast.

In the very best case, where you're 100 miles above the Earth, not in orbit, and not co-rotating at all, you'd see the Earth move at a speed of about 0.2 degrees across your field of view per second. That isn't nothing, and you probably would notice it if you were paying attention, but it's easily lost in other motion. For comparison's sake, a finger at arm's length covers about 1 degree, so an object directly below you would take about 5 seconds to cross the width of your finger at arm's length. Or, put another way, it would move across your field of view at about the same rate as a person walking slowly on the other side of a football field from you.

Fundamentally, it looks slow because of parallax: faraway objects don't move across your field of view very quickly even when they're moving very fast.

In practice, though, you never get even that much, because:

• If you're in orbit anywhere near the Earth, you're actually moving faster than the Earth rotates (by a lot!), so you mostly see your movement over its surface. You're also higher than the 100 miles in our example: both active space stations (the ISS and China's Tiangong) orbit at about 250 miles up.
• If you're not in orbit, you probably just launched from the surface of the Earth, and you still have the horizontal momentum you started with, so you're still more-or-less co-rotating with the Earth.

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> Imagine holding a ball at arm's length

This is a little misleading, because a tennis ball at arm's length would be a closer analogy to the view from geosynchronous orbit. A tennis ball has a diameter of about 2.5 inches, and the average human arm is ~25, so you're viewing from ~5 radii away. The Earth's radius is ~4,000 miles, so you'd be viewing from ~20,000 miles away (geosync orbit is 22k).

The view from the ISS is more like holding a ball (250 miles / 4000 miles) * 2.5 inches = 0.16 inches sorry, twice that, 0.32 (since one of those is a radius and one is a diameter) from your eye, at which point it would be brushing against your eyelashes.

But it turns out the rotation's still pretty slow even that close up.

Anything that gets launched into space is already going at least the same speed as the Earth's rotation. It's not like it gets to space and then just slows down on its own. If anything it might be going faster than the Earth is rotating.

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Perhaps the video is being taken from a geosynchronous orbit? Or a still photograph?

A lot of really good answers already. One thing I didn't see mentioned is you may also see videos from geostationary orbits which would make it look like the earth isn't rotating at all (though if you pay attention you'll notice space is "rotating" behind it). Could be messing with your perception depending on the context.

Their explanation is perfect and illustrates it well enough, considering this is EILI5.

The numbers you’re hearing are linear speed, not angular speed.

vᵣ=rω where v is the linear speed, r is the radius of rotation and ω is the angular speed.

For earth, r = 3950 mi, and ω = 15°/h. This gives vᵣ= 3950×15×π÷180=1034.107666 mi/h (π÷180 is just a unit conversion) at the equator. Sound familiar?

Now, what really matters is ω - that 15°/h. This is half the angular speed of the hour hand on a clock. The hour hand on a clock goes around twice in a day, which works out to 30°/h. That’s not a movement we can easily perceive when viewed from altitudes like the one the Blue Marble photo was taken at, the perspective we have of the earth is very similar to the perspective we have of a clock. The angular speed is just slow enough we can’t perceive it.

Edit: unit errors in my math

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In videos taken from the ISS you see some motion, but that's mainly the orbit of the ISS around Earth (which takes just ~1.5 hours, so it's much faster than Earth's rotation).

>vᵣ=rω where v is the linear speed, r is the radius of rotation and ω is the angular speed.

>For earth, r = 3950 mi, and ω = 15°/h. This gives vᵣ= 3950×15×π÷180=1034.107666 mi/h (π÷180 is just a unit conversion) at the equator. Sound familiar?

That is not explaining like I'm 5 lol, but actually a really good answer, ty.

I wish there were a simpler way to explain where the big number comes from, but unfortunately there isn’t.

All the other methods I’ve learned for dealing with spinning things involve far more complicated math - usually matrices and reference frame conversions. This would be more of an ELI20, where v=rω is more like ELI8.

also as well as what others have already said, some space craft often orbit in geosynchronous orbit, which means they hold position above the earth by moving at the same speed as the rotation, so if you and the earth are rotating at the same relative speed it will look like it's not moving

From low orbit the rotation is basically unnoticeable. The ground moves under you at 400-something m/s but you yourself are flying by at 7000+ so you're just trying to spot the ground move by under you slightly slower than expected.

Of course at near GSO you'd observe the earth being almost completely motionless because you have almost the same rotation period over it as the surface (you'd get to watch the dusk/ dawn line move over the surface at the expected speed though)

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> From low orbit the rotation is basically unnoticeable. The ground moves under you at 400-something m/s but you yourself are flying by at 7000+ so you're just trying to spot the ground move by under you slightly slower than expected.

Yes, all of which I already said in my own top-level comment. But that's not an issue of distance, really, it's an issue of Earth's mass - the same wouldn't be true of a proportional orbit around a tiny asteroid.

OK, what about the fact that earth is orbiting the sun at 67,000mph? How is it possible to see the earth from space if earth is constantly moving that fast and there's no way a space station or satellite can move that fast with earth and follow it?