# can we estimate the number of habitable planets within a specified distance from Earth?

For the purposes of this question, I will define "habitable" as:

• rocky composition like Earth
• orbiting a relatively quiet star, like our Sun
• far enough from its host star to not be tidally locked
• receiving about the same amount of energy from its host star as we do (in the star's habitable zone).

Thus, a "habitable" exoplanet would be capable of holding on to an atmosphere conducive to life, and, if any water was present, it could exist in liquid form on the planet's surface.

Kepler data has revealed numerous planets orbiting numerous stars in only a small slice of the sky. Many of these planets have been characterized to some degree. There are compiled lists of potentially habitable exoplanets.

My question is whether the findings so far can inform a reasonable estimate of the total number of habitable (or potentially habitable) exoplanets within a given number of light-years distance from Earth, or if further sky surveys and studies would be needed. In other words, can we pin down the first few terms of the Drake Equation and apply it to our neighborhood in the galaxy?

• Certainly on-topic both here and in Astronomy SE. Search for "Drake" here returns 14 hits, and 26 hits in Astronomy. exoplanet tag has 36 questions here, and 211 questions in Astronomy. If no good answers appear here after a while, one might consider then moving there. However it gets a little harder to move a question yourself once answers begin to appear. To me it seems that the analysis of an exoplanet database is more like something that would get an answer there than here, but you never know! – uhoh Sep 19 '18 at 4:59