Drake’s Equation is an equation used to estimate the number of detectable extraterrestrial civilizations in the Milky Way galaxy. Invented by Frank Drake, the founder of SETI.

Can We Help with Your Assignment?

Let us do your homework! Professional writers in all subject areas are available and will meet your assignment deadline. Free proofreading and copy-editing included.


  • 1011 Stars discovered so far

Fp (0.5) Half the planets in the Milky Way galaxy have stars around them

Ways to detect planets

  • Transit Method: Diming of star due to planet revolving around it
  • Astrometry/ Doppler Spectrometry: Wobbling of star due to planet revolving around it
  • Direct Imaging: Using optical telescope to directly see massive planets around parent stars

***Thanks to Kepler telescope; we can detect smaller planets; earth-like size

Ne (2.0) Based on the distance from the parent star

  • Each star has a particular distance you can be away from it to develop life
  • Called the Habitable Zone (Defined by present of LIQUID WATER) MUST BE LIQUID
  • Based on molar mass (H20) should be a gas at 25C but remains a liquid due to: 1) COHESION (hydrogen bonds-stick together) 2) HIGH HEAT CAPACITY 3) HIGH HEAT OF VAPORIZATION
  • Increase star size= move habitable zone BACK
  • Decrease star size= move habitable zone FORWARD

Fl (1.0)

  • Because all planets capable of forming life will eventually develop life

Fi/Fc (10% for both)

  • Only applicable to planets in habitable zone
  • NOT EASY TO ESTIMATE (This valve is greatly debated)


  • Longer civilization is around, increased likelihood of finding them
  • BUT not how old civilization is; its age is determined by when they first evolved communication
  • We are about 100 years old with communication / (Age of the Universe (10 bya))
Lab Report Explained: Length and Electrical Resistance of a Wire

Fermi Paradox

The Drake Equation predicts a large amount of intelligent civilizations, however we have found NONE!

Why haven’t we found anyone?

  • Maybe distance is too great
  • Maybe Our technology could be incompatible; we can’t detect each other
  • Maybe NO other civilizations exist

Inline Feedbacks
View all comments