# What is the angular momentum of earth?

##### 1 Answer

#### Answer:

The angular momentum due to the earth's rotation is

(this value is with respect to a co-moving observer)

#### Explanation:

We can estimate the angular momentum due to the earth's rotation by approximating the earth by a uniform sphere of

- mass
#M= 6.0times 10^24\ "Kg"# and - radius
#R = 6.4 times 10^6\ "m"#

The moment of inertia of a uniform solid sphere about any axis passing through the center is

and so, for the earth it is

The earth's angular velocity is

So, the angular momentum of the earth's rotation (with respect to an observer co-moving with it) is

Note that

- the angular momentum due to the revolution of the earth (with respect to the sun)is much larger than this.
- since the earth actually has a dense inner core, the actual moment of inertia is smaller than that estimated here.