Star-gazers will be able to learn even more about space if a £15m revamp of the Royal Observatory is successful.
The new planetarium should open in 2007
The National Maritime Museum has launched an appeal to pay for changes at the world-famous observatory, in Greenwich, south-east London.
Improvement plans include replacing the planetarium, boosting educational resources and providing better facilities for visitors.
Broadcaster Peter Snow is leading the 330-year-old observatory's appeal.
He said: "Our ambition is to create a spectacular new environment in which more and more people can appreciate the wonders of time and space."
Technological improvements to the planetarium mean the observatory's astronomers will be better able to interpret the skies.
One third of the site that was previously closed to the public will be revitalised with disabled access, a shop and catering area.
English Astronomer Royal, Sir Martin Rees, said: "Visitors will better understand and be able to ask fundamental questions about the forces that have shaped our Universe and allowed human life to emerge."
It is hoped the new planetarium will open in 2007.
Entry to the observatory is free but organisers say a £1 donation from each visitor would kick-start the appeal.
Anyone wishing to make a donation should call 020 8312 6552.