# Definition:Earth

## Definition

Earth is the planet on which we live.

It is the third planet of the solar system from the sun.

Its orbit lies between those of Venus and Mars.

### First Approximation

To a first approximation, the shape of Earth can be considered to be spherical.

### Second Approximation

To a second approximation, Earth is an oblate spheroid.

## Also known as

Earth can sometimes be seen referred to as the globe (sometimes with a capital: the Globe), which is of course just a synonym for sphere.

This nickname is of no more significance than referring to one's own home as (for example) the house, but it gives rise to the adjective global, which is new-age speak for worldwide.

In the field of science fiction the name Terra is more frequently seen than anywhere else, often used to refer affectionately as the original homeworld of the human race.

## Linguistic Note

Earth is a proper name: that of the planet on which (at time of writing) all humans live.

As such, its correct styling is for it to start with a capital letter.

This is the convention to be used on $\mathsf{Pr} \infty \mathsf{fWiki}$.

However, in much literature it can be seen referred to as the earth, which is a bit like, for example, referring to Albert Einstein as the albert.

In recent literature, particularly popular, new-age and poetic, there is a trend to referring to the place as Planet Earth.