# How dependent is Earth is with the other Planets' gravity? [duplicate]

How would the Earth be affected if the Moon was destroyed as far as our orbit around the Sun? What if Mars or Jupiter was destroyed?

## 1 Answer

The orbital speed of the Moon around the Earth is 1022 m/s. The Earth is 81 times more massive, than the Moon. Thus, a sudden disappearance of the Moon would cause an $$\frac{1022}{81}=12 \frac{m}{s}$$ change of the Earth's orbit, which would be negligible.

The disappearance of the Mars or Jupiter would have yet lesser effect.

• How do you justify that claim - in particular since the moon's orbital momentum does not directly affect the Earth's orbit (it does affect wobble and rotation) Oct 3 '18 at 16:05
• The Earth and Moon both rotate about their common barycentre. The Earth at roughly 12.5 m/s the Moon at about 1 km/s. The barycentre is in orbit around the Sun. So if the Moon vanished the Earth would be moving at 12.5 m/s relative to the orbit of the former barycentre, and would settle into a slightly different orbit as a result. Oct 3 '18 at 21:30