The mobile edition has been made by the BBC rather than "the great publishing houses of Ursa Minor" who, in Douglas Adams' book, created the original.

Owners of smartphones and handheld computers will be able to access the guide while they are out and about.

The portable edition contains 7,000 articles from the H2G2 site covering life, the Universe and everything.

The original idea for Earth's very own version of the guide put together by anyone who had time to contribute came from Adams himself.

Mostly harmless

Mr Adams' own company managed the project in its early days but in 2001 the BBC took over and moved it to its current website.

In some respects the way that the H2G2 website was put together pre-figures the idea of the wikipedia, an online encyclopedia, that is also written, edited and checked by ordinary web users.

Phone and PDA users can get access to the mobile version of the guide by sending "H2G2" in a text message to 81010 or simply visiting http://www.bbc.co.uk/mobile/h2g2.

You can also check : Top News News of the Week

"Douglas Adams was years before his time," said Tony Ageh, BBC controller, Internet. "But thanks to modern mobile technology, what was once only a harebrained idea has now become a startling reality."

Mr Ageh said that the entries picked for this edition were the most relevant and useful for mobile users.

"We cannot take for granted what any of the mobile interfaces are," he said, "but its a reasonably pleasant experience on most mobiles."

"We're quite pleased that we have delivered the vision that Douglas had in the first place," he said.

In Douglas Adams' first book the Earth only merited a single short entry in the guide but the phone edition holds information about a huge variety of subjects; everything from how to hypnotise a chicken to hangover cures.

Entries under "Life" cover animals, plants and humans. Those under "Universe" concern geography and space, and "Everything" deals with everything else.

The mobile edition of the guide has been timed to coincide with the release of the Hitchhiker's Guide to the Galaxy film.

Also being updated is the Radio 4 Hitchhiker's website that is offering new versions of the game of the book and radio series.

The BBC is also planning to broadcast the last ever radio instalment of the Hitchhiker's Guide to the Galaxy, starting on 3 May at 1830BST and running until 21 June, with repeats on Thursdays at 2300BST.