Arthur C. Clarke at 90

Arthur C. Clarke, the famed science fiction writer who is also credited with the invention of the communicatioms satellite, celebrated his 90th birthday with a party Sunday and listed three birthday wishes. One was that the world switch to clean sources of energy. Another was for the end of the civil war in his adopted home of Sri Lanka. His third wish was for evidence of extraterrestrial beings.

At this stage of human civilization, the only way we will find such evidence is if those beings make themselves obvious to us in some deliberate way. Over the next few years and decades, humans, by our own efforts, may find simple life forms on Mars or Europa or Titan. Or, we may find extrasolar planets with atmospheric compositions that tell us they are likely the abodes of life. Clarke's wished for ET beings, however, would seem to be of a different order than simple alien bacteria.

The best shot at granting Sir Arthur's wish on that score any time soon is the world's SETI efforts, but there is also another intriguing possibility. Clarke himself has written stories about humans finding alien artifacts in our own solar system-- abandoned alien ships silently orbiting the Sun, or an alien probe waiting for us on the Moon. After nearly 50 years of exploring the Solar System, finding such artifacts cannot be ruled out.