Why don't we feel the Earth spinning?

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👩🏽‍💻 I'm Dr Becky Smethurst, an astrophysicist at the University of Oxford. I love making videos about science with an unnatural level of enthusiasm. I like to focus on how we know things, not just what we know. And especially, the things we still don't know. If you've ever wondered about something in space and couldn't find an answer online - you can ask me! My day job is to do research into how supermassive black holes can affect the galaxies that they live in. In particular, I look at whether the energy output from the disk of material orbiting around a growing supermassive black hole can stop a galaxy from forming stars.

[DrBecky]

A fun short one from me this week, filmed before I went away on holiday last week. A much longer Night Sky News coming next week 👍

[marxbanger]

i only feel the earth's rotational spin when i'm drunk.

[Rubrickety]

Of course, when we move north or south, our velocity due to earth’s rotation does change (because the speed of rotation is zero at the poles). Hence the Coriolis “force”. This is why toilets in Australia have trolls in them.

[michaelphillipps]

Ok that time-lapse video with the fixed star position was wicked cool.

[dangmangcarpenter]

I feel it spinning every Friday night.More so on Saturday morning.

[frankowalker]

That fixed star time lapse blew me away. What stunning photography.

[MustafaAlmosawi]

The three beats of watching this video.

1. Some dude singing. Wait a minute, this a Dr Becky video, right? Did I click on the wrong link?
2. Dr. Becky, mug in hand, taking a sassy sip. What’s going on now?
3.. Lets Physics the Hell out of this.

Mood.

[duprasi]

Actually the spinning of the Earth has some (small) effect on Earth's surface. Namely the centrifugal force "pulls" us away from Earth's rotational axis. For this reason at the equator gravity appears about 0.034m/s² weaker than it would be on a still Earth (or at the poles). Furthermore, because the centrifugal force is't necessarily aligned with the gravitational force, the apparent center of gravity shifts slightly towards the equator, depending on where you are (up to 0, 595° at 26, 3°N/S).

It took me way too long to calculate this ....

[okicutoo]

Star trails tell us much. For example, if you watch any video of star trails with the moon, you will see that the moon @ .02 light seconds away travels the same distance as a star 500 light years away. That a serious parallax problem. In the current model, the earth is chasing the sun @ 448, 000, 000+ mph while orbiting the sun @ 66, 000+ mph. Photographing star trails is very difficult. Any movement, even a light breeze on the camera will be seen. The fact that the mach 550, 000+ movement is not felt or seen in the star trails is solid evidence that we are stationary.

[michelle_h]

"Let's physics the hell out of this"

Literally my favourite line ever! That just made my day😂

[TotalRookie_LV]

One rotation per 24 hours isn't exactly a mind blowing speed that would confuse our senses.

[filopat]

I have a vivid memory from the time when I was five or six years old and I was alone lying on my back late in the evening among the pine trees near our house, watching trees pointing to the starry sky above me and physically feeling the earths rotation. It's a strong and important memory to me and no matter how much math and physics you throw at me, you can't convince me that I wasn't able to feel the rotation. I did feel it!

[Edsbar]

1000 miles per hour at the equator, less in sunny Oxford at about 52.5° north. An angular speed of one revolution per day or rpm doesn't quite have the racing car appeal does it.

[harpoon]

There is an acceleration we experience from the earth rotating. The reason we don’t feel it, is because it works in the direction just opposite of earth’s gravity and it only makes us feel slightly lighter. But since it is always there, and changes only very slowly when we move away or closer to the equator, we don’t notice.

[condorboss]

1:40 That's the FIRST terminal velocity. The _second_ terminal velocity is after you hit the ground because you kept your eyes closed and forgot to open your parachute. ;P

[mopar_dude]

I felt the Earth move last Friday, but it could have just been the Bourbon.

[thomaskositzki]

I fund this video actually a bit... badly explained? 'Badly' is too hard a word, but I am just a German, I haven't got any better at the moment. :)

Additions:
1) One of the reasons why we don't feel constant movement (the one that matters here I think) is a biological one. It is connected to how the inner ear's organ for detecting movement, the semicircular canals with their otoliths, are set up. They are basically little calcium carbonate crytsalls moving about in little canals - that movement is detected by hair cells and send to the brain. So they can only detect acceleration and deceleration.
2) Also there is one very distinct field where you are confronted with the movement of the earth very directly: military gun ballistics. Already back in WW2 and before the gun ranges were such (for artillery, but also for tanks) that the Coriolis effect was noticable enough to be included in training manuals. When you fired along a north-south-axis, you had a sligh deviation to either side, depending on direction. Firing eastwards, shot fell a little short; firing westward, shot went a little longer.

Hope you don't mind me being picky. ^^

[SarahLavenderASMR]

Loved this so much! Super interesting. I'm still in awe that you listen to my videos while working. 😊❤️ Cheers!

[robertjhall]

“Let’s physics the hell out of this.” - Love it!

[davemmar]

Semicircular canals in the inner ear are designed to sense acceleration/deceleration or change in direction. Because of the design of this mechanism we can feel a sense of motion but only temporarily. Once the fluid in the inner ear matches any change in motion, the cilia assume a stable position and we no longer feel motion. I do this experiment with a Barany Chair but an office chair works well too. Have someone spin you around and you will feel the acceleration for 15- 20 seconds and then nothing. Try it with your eyes covered, and then uncover them to see you are still spinning.