The first step towards estimating the number of habitable planets was the presentation of the Drake equation by Frank Drake at the SETI (Search for Extra-Terrestrial Intelligence) Conference, 1961 in West Virginia. The equation is: `N=R*f_p*n_e*f_l*f_i*f_c*L`
- `N` is the number of civilization in a galaxy with whom communication is possible.
- `R` is the average rate of star formation in the given galaxy.
- `f_p` is the fraction of the stars that have planets.
- `n_e` is the average number of planets per star that can support life.
- `f_l` is the fraction of the planets that can support life that actually develop life at a point in time.
- `f_i` is the fraction of planets with present life which can develop into civilizations.
- `f_c` is the fraction of civilizations that develop the technology to be able to release detectable signals into space.
- `L` is the time period for which the civilization continues to release signals.
Even though this is an equation, it is not supposed to be solved by multiplying the increasingly restrictive series of fractions. It is important for contemplation of the above mentioned factors while estimating the possibility of life on some planet in a given galaxy. The values of the last four factors, namely `f_l, f_i, f_c, L`
are highly variable and subjective and hence this equation is used merely for the purpose of contemplation and not for finding exact number of planets that can support life. Considering these factors, one can guess whether a given planet of a given galaxy can support life and civilization and whether we will be able to communicate with the civilization of this planet.
there are almost more than a thousand system in the universe which might at their proper condition will suffice to create a livable planet. to make like harbor it takes sufficient energy from an efficient source in the case of our planet (or system) it is our nearest star (the sun) then the right elements must be present like the premodial element, hydrogen, other elements like oxygen, nitrogen and carbon dioxide. the right amount of these elements are essential to sustain life. according to what i learn there are some creatures like fruitflies who could survive even outside our atmosphere and there were some evidence as to the moons of saturn or jupiter that contains some trails which may signify the presence of a water source and as we know water is life, we could conclude some facts on it but as for now our planet is the only planet that could support life.