Aliens have been popular fodder for Science Fiction for the past century, showcasing creatures that range from H.G. Wells’s Martian invaders to Star Trek’s Vulcans. However, extraterrestrials may exist beyond the realm of our imaginations. Scientists have long searched for creatures elsewhere in the universe, whether alike or dissimilar to the creations of our fiction. Given suitable conditions and sufficient time, life should be able to evolve elsewhere in the universe, just as it has here on Earth.

One of the leading institutes involved is the Search for Extraterrestrial Intelligence (or SETI). SETI, has teams of scientists working on searching for the various fingerprints of life. One branch of SETI’s research involves using spectroscopy to analyze discs of forming stars—this will tell the relative abundances of elements present, and whether or not those elements are in the correct proportions to support life. For instance, a solar system must have plenty of carbon to support carbon-based life, as well as nitrogen for DNA, oxygen for respiration, iron, ext. Since only the largest of stars are capable of fusing up to Iron, when these stars go supernova it creates the perfect mixing pot for life to form.

One tool to estimate the probability of us discovering an alien civilization is the Drake equation, a formula created by astrophysicist Frank Drake. The equation takes into consideration many of the main factors in alien life: it multiplies the average rate of star formation in our galaxy, the fraction of those stars that have planets, the average number of planets per star that could potentially support life, the likelihood that a planet will develop life, the fraction of these planets that will develop civilizations with communication, and the length of time that these civilizations have existed on these planets. Many of these criteria, such as the rate of star formation, are known fairly well while others, such as the likelihood that communicating civilizations evolve, have no way to be accurately estimated.

In addition to us looking for aliens, we have given the aliens a few tools in case they’re looking for us. When we launched the two Voyager spacecrafts in 1977 we included two golden phonographic plates which contained a variety of sounds and images from Earth, ranging from the sound of thunder to excerpts of Bach, from images of multicultural cuisine to diagrams of vertebrae evolution. We have also included our position in the galaxy relative to nearby pulsars, so that aliens can use pulsars to find us the way sailors use lighthouses to find the shore.

There is a significant chance that these searches will fail over my lifetime, or perhaps forever: the universe might be too expansive for evolved civilizations to ever find each other, the way life has evolved elsewhere might be too foreign for us to even recognize as life, and perhaps we are a cosmic anomaly and Earth is the only home to life in the universe. However, if we don’t try, we could miss our chance for the greatest discovery imaginable.