Do you believe that life exists on other planets? As the search continues, we trust our instincts that we are not alone. The best place to find life like our own is a Goldilocks Planet.

"Goldilocks planet" is a colloquial term for a planet that falls within a star's habitable zone, often specifically used for planets close to the size of Earth. The name comes from the story of Goldilocks and the Three Bears, in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is "just right". Likewise, a planet following this Goldilocks Principle is one that is neither too close nor too far from a star to rule out life (as humans understand it) on the planet.

Goldilocks planets are of key interest to researchers looking either for existing (and possibly intelligent) life or for future homes for the human race. The Drake equation, which attempts to estimate the likelihood of non-terrestrial intelligent life, incorporates a factor (ne) for the average number of life-supporting planets in a star system with planets. The discovery of extrasolar Goldilocks planets helps to refine estimates for this figure.

Very low estimates would contribute to the Rare Earth hypothesis, which posits that a series of extremely unlikely events and conditions led to the rise of life on Earth. High estimates would reinforce the Copernican mediocrity principle, in that large numbers of Goldilocks planets would imply that Earth is not especially exceptional.

Goldilocks Planet Wikipedia

  Goldilocks Planet   YouTube

Goldilocks moons   PhysOrg - January 16, 2012

The search for extraterrestrial life outside our Solar System is currently focused on extrasolar planets within the habitable zones of exoplanetary systems around stars similar to the Sun. Finding Earth-like planets around other stars is the primary goal of NASA's Kepler Mission. The habitable zone (HZ) around a star is defined as the range of distances over which liquid water could exist on the surface of a terrestrial planet, given a dense enough atmosphere. Terrestrial planets are generally defined as rocky and similar to Earth in size and mass. A visualization of the habitable zones around stars of different diameters and brightness and temperature is shown here.

  Alien planet looks 'just right' for life   MSNBC - September 30, 2010
Astronomers say they've found the first planet beyond our solar system that could have the right size and setting to sustain life as we know it, only 20 light-years from Earth.

  Alien life certain to exist on Earth-like planet, scientists say   Telegraph.co.uk - September 30, 2010

Alien life certain to exist on Earth-like planet, scientists say. The chances of alien life existing on a newly-discovered Earth-like planet are 100 per cent, an astronomer has claimed.

Scientists find potentially habitable planet near Earth   PhysOrg - September 29, 2010

If confirmed, this would be the most Earth-like exoplanet yet discovered and the first strong case for a potentially habitable one. To astronomers, a "potentially habitable" planet is one that could sustain life, not necessarily one that humans would consider a nice place to live. Habitability depends on many factors, but liquid water and an atmosphere are among the most important.