It is said that Bowie wrote this song after watching the 1968 Stanley Kubrick movie '2001: A Space Odyssey' (see gallery of best space-related movies).
The sad lyrics tell the story of Major Tom, a fictional astronaut who cuts off communication with Earth and floats into space. The character was featured in other songs by Bowie and in the hit 'Major Tom', by German singer Peter Schilling, which is also on this list.
"This is Major Tom to ground control
I'm stepping through the door
And I'm floating in a most peculiar way
And the stars look very different today"