What are the odds there is life in outer space?

Odds of Extraterrestrial Life: Cheat Sheet

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.

Now, test your knowledge with these quizzes!

  • Space Out: Mars Quiz
  • Astronaut Quiz
  • Space Shuttle Quiz
  • Moon Quiz

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