Our astronomical knowledge increases on a daily basis, but we still have no tangible proof that extraterrestrial life exists elsewhere. Although the universe is a vast place, where planets are common and water is abundant, there is still no sign of aliens. The frustration and surprise at our inability to detect alien life is perfectly summarized in the Fermi paradox: If the conditions for life are so common across the cosmos, where is everybody?
Although fruitless so far, the search for alien life might be at a turning point. With the discoveries of potentially habitable terrestrial planets, the imminent launch of new dedicated telescopes, and other promising space missions, we might soon find definitive proof of extraterrestrial life. The following are the areas through which we are aiming to find ET.
The search for alien life has been on the mind of scientists, inventors, and the general public since at least the late 19th century, but it has been mostly limited to the hope of hearing radio signals emitted by other civilizations and the discovery of life in our Solar System.
The Search for Extraterrestrial Intelligence (SETI) is probably the most famous organization dedicated to monitoring electromagnetic radiation for signs of alien transmissions. Most of SETI’s work is focused on analyzing radio waves in the hope of finding a signal of clear artificial origin. They do this by observing thousands of stars in our galaxy for a clearly artificial signal, but so far nothing has been found.
The Wow! Signal Big Ear Radio Observatory and North American AstroPhysical Observatory (NAAPO)
So far, only one detection in 1977 – which was not by SETI – couldn’t definitively be explained as a natural phenomenon (its exact origin is still unclear). The mysterious signal – also known as the "Wow! signal" – was a 72-second-long narrow-band radio detection. It came from an area in the sky devoid of stars and planets, but it was never detected again, despite 50 more observations of the same area in the following decades.