I understand that scientists believe the earth and the moon were spinning at the same speed as each other at the time they experienced acceleration (were formed). I also know that the reason given for why the moon no longer spins is that the earths gravitational attraction for the moon stole the energy after 3.5 billion years.

So why is the earth still spinning?

Given that the sun's attraction for the earth is 100 times stronger than the earths attraction for the moon.

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    $\begingroup$ you mean spinning around itself ? because the moon still spins around itself. $\endgroup$ – Ismasou Jun 3 '17 at 20:26
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    $\begingroup$ It is the tidal force that robed the moon of its spin. The sun/earth tidal force is small compared to the earth/moon tidal force. $\endgroup$ – Lewis Miller Jun 3 '17 at 20:31
  • $\begingroup$ See tidal locking $\endgroup$ – lemon Jun 3 '17 at 20:38
  • $\begingroup$ Related: physics.stackexchange.com/q/112336/2451 and links therein. $\endgroup$ – Qmechanic Jun 4 '17 at 1:15
  • $\begingroup$ The Earth is still spinning because it was spinning 4.5 billion years ago. Just as an external force is needed to make a moving object slow down, an external torque is needed to make a spinning object slow down. There are external torques on that act on the Earth, but they are rather small. $\endgroup$ – David Hammen Jun 4 '17 at 7:57

Tidal forces rely on the difference in gravitational force between the different parts of the Earth and Moon due to the different distances

The Sun is so much further away that the differential force on the different parts of the Earth is much smaller, the system is much closer to two point masses and so (almost) no tidal torque

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    $\begingroup$ Not "no tidal torque", just "much less tidal torque." Earth's rotation is slowing down and, given enough time, it would first become tidally locked to the Moon, and then I suppose eventually the rotation of the Earth-Moon system would slow down until it became a single body tidally locked to the Sun. But of course the Sun will expand and swallow the Earth long before any of that happens. $\endgroup$ – Nathaniel Jun 4 '17 at 1:17
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    $\begingroup$ @Nathaniel, next to no tidal torque ;-) $\endgroup$ – Martin Beckett Jun 4 '17 at 2:19

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