Just kidding. Didn't you think we'd have more to say than that?
Earth is the third planet in the Sol system, located in Sector ZZ9 Plural Z Alpha of the Milky Way galaxy, orbited by its moons Luna and, from AD 3001 onward, the Ruby Moon of Doom. Earth is often referred to by its Latin name Terra, not to be confused with Terra Androgena. It is also known as "Ick" on planet K-9 and has been nicknamed "The Planet of Rose and Silver" due to the light cast by its moons.
It is in fact a computer envisioned by the supercomputer Deep Thought for the purpose of figuring out the Ultimate Question of Life, the Universe, and Everything. The Magratheans were commissioned by Mice to build it and it is so complex that organic life forms a part of its matrix. However, the original inhabitants were wiped out by Golgafrinchan colonists who became the primary ancestors of modern Earthlings, who long fancied themselves the most intelligent species on the planet but in fact came in second to Mice and Dolphins respectively. Other sentient species on the planet include Mailburros, Cats (not native), Dogs (not native), and Cattle (sometimes).
Because of its location in a plural zone, a version of Earth unfortunately exists in nearly every dimension. The "primary" Earth resides in Dimension Q. Many of these alternate versions differ only in minute and inconsequential details and are thus not worth differentiating whereas others, such as Mungus, NowWhat, Piscis Magni, and Poptropica, vary considerably.
Earth has long been ignored or underestimated by the intergalactic community at large; disdained for the inhabitants' violent tendencies and obsession with primitive technology like digital watches, and left out of many guidebooks altogether. However, largely owing to its artificial creation, it is in fact a paragon of natural resources and a veritable oasis in space, and has drawn the attention of envious eyes for ages. More invasions of Earth have been attempted than of any other known planet. Why so few have succeeded remains a mystery but sheer dumb luck is the most commonly postulated theory.
The original version of Earth was demolished by a Vogon Constructor Fleet, ostensibly to make room for a hyperspace bypass. However, Vogon Prostetnic Jeltz was in fact acting upon orders from psychiatrist Gag Halfrunt on behalf of psychiatrists everywhere who did not wish to see their profession wiped out by all of their patients knowing the meaning of life, the universe, and everything. Earth Mark II was commissioned as a replacement within hours of the original's destruction, but abandoned while in the final building stages. Before leaving for parts unknown the Dolphins pulled an alternate Earth into Dimension Q to take its place, which was completely identical aside from their absence and left its inhabitants none the wiser aside from talk of "mass hallucinations".
A few years later, in AD 1989, the infamous "Earth Question" of how to handle the planet's unruly inhabitants came to a head, and the planet faced either nothing, quarantine, invasion, or a second destruction. This latter option became the most likely and only a radical new scientific theory about Earthlings, demanding a great deal more study, saved it.