Drake Equation
The Drake Equation was developed by Frank Drake in 1961. This equation is used to estimate the number of detectable extraterrestrial civilizations in the Milky Way galaxy.
The Equation is - N = R* fp ne fl fi fc L
where, • N = the number of civilizations in our galaxy with which communication might be possible;
• R* = The average 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 (the average number of planets that can potentially support life per star that has planets)
• 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 civilizations that develop a technology that releases detectable signs of their existence into space (or we can say that the fraction of communicative planets (those on which electromagnetic communications technology develops)
• L = The lifetime or Life-span of communicating civilizations.
The equation is very simple but it is very hard to find out the values of these factors. But This equation basically focus on the factors which determine how many intelligent, communicating civilizations there are in our galaxy. Scientists are continously studying to find the values of these factors with great accuracy. The Drake Equation is an attempt to encapsulate all the variables that would be relevant to establishing the number of intelligent civilizations that existed in the Milky Way galaxy and which were broadcasting radio signals at this particular point in time. The Drake Equation is composed of seven terms. The first six are used to compute the rate at which intelligent civilizations are being created and the final term identifies how long each lasts on average as a broadcasting civilization. It is worth stressing that the Drake Equation applies only to intelligent civilizations in the Milky Way galaxy. It does not apply to civilizations in other galaxies because they are too distant to be able to detect their radio signals.