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The Probability of Finding Aliens Is Now Three Times Higher

Keck Observatory

By Jesus Diaz

The total number of stars in the Universe “is likely three times bigger than realized.” Yale University astronomer Pieter van Dokkum says there are “possibly trillions of Earths orbiting these stars,” dramatically increasing the possibility of finding alien civilizations.

According to the new study just published in Nature, new observations on the red end of the optical spectrum at the W. M. Keck Observatory in Hawaii show an overwhelming population of red dwarfs in eight massive nearby elliptical galaxies. The team has discovered that these galaxies hold twenty times more red dwarfs than the Milky Way.


Van Dokkum says that “there are possibly trillions of Earths orbiting these stars” which are “typically more than 10 billion years old.” According to him, that’s long enough for complex life to evolve, which is “one reason why people are interested in this type of star.” In fact, astronomers discovered the first exoplanet similar to our own Earth—and therefore capable of harboring complex life—orbiting the Gliese 581 red dwarf star system, 20.3 light years from our home planet.

Carl Sagan explains why this discovery has a dramatic impact in our search for intelligent life in the Universe, using the Drake Equation:

Logically, if you increase the number of stars in the universe by three, the number of potential extraterrestrial civilizations increases by three times as well. Whether we make contact or not is another story.

The discovery doesn’t only have a deep impact on the search for extraterrestrial life, but also on our understanding of galaxy formation and the Universe itself. Team member Charlie Conroy—of the Harvard-Smithsonian Center for Astrophysics—says that this might be a sign that galaxies contain less dark matter than originally suspected, since the abundance of red dwarfs “could contribute more mass than realized” to the Universe. [Nature and Keck Observatory]



What is the Drake Equation?
by Steve Ford, WB8IMY


Is there a way to estimate the number of technologically advanced civilizations that might exist in our Galaxy? While working at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr. Frank Drake conceived a means to mathematically estimate the number of worlds that might harbor beings with technology sufficient to communicate across the vast gulfs of interstellar space. The Drake Equation, as it came to be known, was formulated in 1961 and is generally accepted by the scientific community.

N = R* fp ne fl fi fc L


  • N = The number of communicative civilizations
  • R* = The rate of formation of suitable stars (stars such as our Sun)
  • fp = The fraction of those stars with planets. (Current evidence indicates that planetary systems may be common for stars like the Sun.)
  • ne = The number of Earth-like worlds per planetary system
  • fl = The fraction of those Earth-like planets where life actually develops
  • fi = The fraction of life sites where intelligence develops
  • fc = The fraction of communicative planets (those on which electromagnetic communications technology develops)
  • L = The “lifetime” of communicating civilizations

Frank Drake’s own current solution to the Drake Equation estimates 10,000 communicative civilizations in the Milky Way. Dr. Drake, who serves on the SETI League’s advisory board, has personally endorsed SETI’s planned all-sky survey.


(from QST, August 1995, page 38)