Earth

Mostly harmless.

The third Planet from a star named the Sun. The only planet in our solar system whose surface has liquid water, covering over 70% of the surface and dividing it into four Oceans and seven Continents. There is a relatively thick Atmosphere composed of about 2/3 Nitrogen, 1/3 Oxygen, plus trace.

The interior of the Earth is, like the other Terrestrial Planets, divided into an outer silicaceous solid mantle and an inner nickel-iron core. Our planet is big enough to have the core differentiated into an liquid outer core, which gives rise to a weak Magnetic Field, and a sold inner core.

The Earth is unusual in having a large, Terrestrial-like Moon that is about 1/4 of the planetary diameter. By coincidence, the moon is just far enough away to have the same apparent angular size as the Sun. Probably the Moon formed from the collision of a Mars-sized planet into the early Earth, which explains for instance its lack of iron.

The Earth is the only known place in the universe that supports life - see Biology - including intelligent species such as Humans and almost certainly Apes, Dolphins, and maybe a few others.