Stuff You Need to Know:
- Some astronomers involved with the search for extraterrestrial intelligent life, or SETI, use instruments such as radio telescopes to "listen" for aliens.
- At the first official SETI conference in 1961, radio astronomer Frank Drake presented the Drake Equation, a formula that estimates the number of potential intelligent civilizations in our galaxy.
- The Drake Equation produces wildly variable results. Some calculations indicate we may share our galaxy with 12,000 alien civilizations. Carl Sagan suggested that 1 million civilizations might exist in the galaxy.
- After years of searching and finding no ETs, many astronomers now think the values used in the Drake Equation should be ratcheted down. The implication: We may not be completely alone, but we're in no danger of having our personal space invaded.