Scientists now say that our world’s greatest chance of finding anything extraterrestrial is by analyzing the white dwarf stars that orbit around planets with Earth-like qualities, and search for lingering signs of oxygen.

The reason behind this theory is pretty simple:  The presence of oxygen within an atmosphere is an indication that life either exists there currently or existed there at one time. Scientists have based this theory on the pending doom of our own planet; that once all life ceases to thrive on Earth, the oxygen within our atmosphere will diminish to void, because there will not be any plant life left to produce it.

To find potential planetary candidates for sustainable life, scientists believe that they must scour the solar system for stars which fade out whenever an orbiting planet crosses its path. They believe that any Earth-sized planet that has the capacity to block out light fractions is an opportune environment for discovering extraterrestrial biological structures.

Even if we do discover a likely candidate inside the more than 500 closest white dwarfs, scientists say that it will not be until NASA’s James Webb Space Telescope is launched in 2018 that we can truly begin to sniff out habitable planets. Even a tool as advanced as the JWST will still have to review hundreds of hours of transit activity in order to effectively analyze the presence of gasses within the atmosphere.

Unfortunately, sniffing out space gas doesn't appear to be as easy as, say, catching a whiff of Uranus.