He saw the machine disappearing into the sky. All the plants on that piece of ground were dead. When you look up into the night sky, what are you thinking? Do you believe that there are other worlds out there? Is there life in those worlds? Is it like life on Earth? What's out there? Space is perhaps the most exciting mystery - the last big adventure. Governments have spent millions of pounds trying to discover its secrets. So are the stories of aliens and UFOs true? There have been thousands of reports from ordinary people. But space travellers say that they have also seen UFOs. When Apollo 11 made the first famous landing on the moon on 21 July 1969, the spacemen were not alone. Neil Armstrong and Buzz Aldrin saw 'two very large mysterious things' with bright lights. 'They are watching us,' Armstrong reported. This information was kept secret for years by the US government. But there have been many more reports of UFOs from space travellers and pilots of aeroplanes. Have UFOs and aliens visited Earth? Many people say that they have seen them. Some people have taken photographs. Here are some of their stories.