When a bird lets go of a branch and drops to the ground below, why doesn't the moving Earth sweep away from the dropping bird? When a bird lets go of a branch and drops to the ground below, why doesn't the moving Earth sweep away from the dropping bird? The gravity of the Earth keeps the bird moving with the Earth. Friction causes the air to move along with the Earth; the bird moves through the air. The magnetic field of the Earth keeps the bird moving with the Earth. The bird is moving with the Earth and has inertia.

The bird is moving with the Earth and has inertia.

Explanation:

Generally, everything on earth is moving at the same speed as the earth - approximately 460 m/s. Just like a bus carries a passenger, the passenger whether sitting on the bus, will be moving at the same speed as the bus. Its all about relativity by Albert Einstein. The passenger, this time the bird, and the bus being the earth are therefore moving in sync and therefore it feels as though the earth is still. However, the bird has inertia - the tendency to stay at rest or uniform motion in a straight line - and requires some energy to change velocity.

Planes going long distances across time zones have to consider the speed of the earth's rotation in their travel for fuel-efficiency because traveling in the same direction as the rotation of the earth can increase the length of travel (because the destination keeps moving relatively forward, per se', as the earth rotates).