Mostly Harmless
The Guide's description of Earth[src]

Earth was a giant supercomputer designed to find the Ultimate Question of Life, the Universe and Everything. Designed by Deep Thought and built by the Magratheans, it was commonly mistaken for a planet, especially by the ape descendants who lived on it. It was situated far out in the uncharted backwaters of the unfashionable end of the Western Spiral Arm of the Galaxy.

Unfortunately, the Earth was destroyed by the Vogons five minutes before the program was to be completed. The Vogons were sent by the psychiatrist Gag Halfrunt, who thought his profession would cease if the Question were known. Later on, the Earth reappeared but all forms of the Earth were later demolished.

The only two humans to survive the Earth's destruction were Arthur Dent and Trillian.[1]


Earth was mainly populated by "ape-descended life forms" or Humans, which number around 6.5 billion at the time of the earth's destruction. The earth is also inhabited by a series of flora and fauna, including the mice and dolphins, the most and second most intelligent species on the supercomputer respectively, with humans being the third.

Humans do not realize they are only the third most intelligent and are among the most ignorant and technologically backward people in the universe.



A computer of such infinite and subtle complexity that organic life itself shall form part of its operational matrix.
—Deep Thought on the Earth.[src]

When the supercomputer Deep Thought announced the Ultimate Answer as Forty-Two after seven and a half million years of thought, it challenged Phouchg and Loonquawl to say what the Ultimate Question actually was. When they could not, Deep Thought designed a supercomputer that could give the Question, giving it its future name of the Earth.

The Magratheans were then hired to build the Earth, using a method of sucking matter through white holes to construct the vast planet-like computer. Slartibartfast designed the fjords of Norway, for which he won an award.

Prehistoric times[]

Golgafrincham Ark B

Golgafrincham Ark Fleet, Ship B, as seen in the 1981 TV series.

The Golgafrinchan Ark Fleet Ship B crash-landed on Earth, leaving Arthur Dent and Ford Prefect stranded in time.


The psychiatrist Gag Halfrunt thought that his career would cease if the Question were known. Therefore, he got the Vogons to destroy the supercomputer, with the apparent excuse of building a hyperspace bypass. The Vogons destroyed the Earth five minutes before the Question was due to be announced, thereby destroying ten million years worth of work.[2]


Earth appeared in:


  • By the time of its destruction, Earth was 10 million years old. In the TV series however, the Guide states the scientifically accepted age of 4.5 billion years.[3] This might not be a mistake by the filmers though, as Slartibartfast states that Earth was designed to appear older than it really was. It is possible then that the fake geological history misled both human scientists and the editors of the Guide.


  1. Elvis was revealed to be singing at The Domain of The King, though he may not have been human to begin with.
  2. As told to Arthur Dent by Slartibartfast, in chapter 30 of the Douglas Adams novel The Hitchhiker's Guide to the Galaxy.
  3. Episode 1. 1981 TV series.