Why does the earth spin?

Morba · 12 Jan 2011 at 19:40

Was just asked this by my 5 year old boy, have to say it stumped me!
I know why the moon orbits us and why we orbit the sun, but not why the earth itself spins!

Not often he asks something that has me heading for google but I was surprised (maybe naively) with the reason that was offered, though on reading it it makes sense (let's forget religious beliefs on this one).

Anyone else been stumped by a good question from their kids?

PhillyDee · 12 Jan 2011 at 19:43

Why? Difficult one. Gravitation, though I suspect its a massivly complex and pretty difficult subject, as the sun also spins, the galaxy spins, the galaxies spin around the local group centre, and they are all racing toward some unknown and unseen point.

p4radox · 12 Jan 2011 at 19:43

Because there's nothing to stop it. Wiki says:

It is theorized that Earth formed as part of the birth of the Solar System: what eventually became the solar system initially existed as a large, rotating cloud of dust, rocks, and gas. It was composed of hydrogen and helium produced in the Big Bang, as well as heavier elements ejected by supernovas. As this interstellar dust is inhomogeneous, any asymmetry during gravitational accretion results in the angular momentum of the eventual planet.[24] The current rotation period of the Earth is the result of this initial rotation and other factors, including tidal friction and the hypothetical impact of Theia.

Morba · 12 Jan 2011 at 19:45

Yep, nothing to stop it since the start.

Anyway, this isn't about this question, more about questions kids ask

Destination · 12 Jan 2011 at 19:54

DOesn't venus spin the wrong way, and very slowly

a day being longer than a year, thus very bad weather conditions, even if the athmosphere was earth like.

I recall one of Prof Brian Cox's shows on the solar system covering Earth's weather patterns and suggesting without the spin we'd all be buggered.

davedudes · 12 Jan 2011 at 19:57

Four numbers, 2012, im worried are you?

Brian8bit · 12 Jan 2011 at 19:58

davedudes said:
Four numbers, 2012, im worried are you?

No.

contracteur · 12 Jan 2011 at 20:00

I'm pretty sure the Moon slows us down or something; it causes tidal movements which in turn slows down the rotation due to friction.

Andr3w · 12 Jan 2011 at 20:02

davedudes said:
Four numbers, 2012, im worried are you?

Thats one number

daz · 12 Jan 2011 at 20:02

Angular momentum

Vonhelmet · 12 Jan 2011 at 20:03

daz said:
Angular momentum

Yep.

[FnG]magnolia · 12 Jan 2011 at 20:04

Content : we have one of those electronic gates at the front of the house. We were in the car outside the house waiting for the gate to open a while back and my wife asked me, "How does the gate open?"
"This remote sends a signal," I replied smugly, with the beeper thing in my hand.
"But then what happens? How does the gate actually open?"
"Well, it's ... hmmm ... electricity?" I replied, less smugly this time.

We then had an argument about something so we never did finish the conversation.

I don't think it's electricity. Does anyone know how they work or do I have to wait until I go home to see what the box on the ground near the gate actually does?

Docaroo · 12 Jan 2011 at 20:04

Conservation of Angular Momentum!

Castiel · 12 Jan 2011 at 20:04

It is actually slowing down and has been since the great big spinning man in the sky started it off.

davedudes · 12 Jan 2011 at 20:04

Andr3w said:
Thats one number

2, 0, 1, 2 hence four little numbers

craig3000 · 12 Jan 2011 at 20:06

The bloke on star gazing live explained this and why everything spins in the same direction. All do to with how the planets formed in the first place.

Murray · 12 Jan 2011 at 20:06

davedudes said:
2, 0, 1, 2 hence four little numbers

so when someone asks what year it is do you say two-zero-one-two?

Vonhelmet · 12 Jan 2011 at 20:08

[FnG]magnolia;18212717 said:
Content : we have one of those electronic gates at the front of the house. We were in the car outside the house waiting for the gate to open a while back and my wife asked me, "How does the gate open?"
"This remote sends a signal," I replied smugly, with the beeper thing in my hand.
"But then what happens? How does the gate actually open?"
"Well, it's ... hmmm ... electricity?" I replied, less smugly this time.

We then had an argument about something so we never did finish the conversation.

I don't think it's electricity. Does anyone know how they work or do I have to wait until I go home to see what the box on the ground near the gate actually does?

Well, unless it's got a diesel generator attached, I'd be pretty sure it's electricity. It'll be a motor that opens the gates, which will be driven electrically from the mains supply.

Vonhelmet · 12 Jan 2011 at 20:09

Murray said:
so when someone asks what year it is do you say two-zero-one-two?

No, you say two-zero-one-one.

Murray · 12 Jan 2011 at 20:09

vonhelmet said:
No, you say two-zero-one-one.

screw you!!!