Top 5 Questions About the Cosmos That Still Baffle Astronomers Today

 In 1961, astrophysicist Frank Drake devised a highly controversial equation: By multiplying together a series of terms relating to the probability of extraterrestrial life (the rate of star formation in the universe, the fraction of stars with planets, the fraction of planets with conditions suitable for life, etc.) he surmised that the existence of intelligent life on other planets is extremely likely.

One problem: Roswell conspiracy theorists notwithstanding, we haven’t heard from any aliens to date.

Recent discoveries of distant planets that could theoretically harbor life, though, have raised hopes that we might detect extraterrestrials if we just keep looking.