Back in 2009, NASA launched the Kepler Space Telescope, whose sole purpose was to stare at a section of the night sky in search of planets outside our solar system. Nine years later, on October 29, 2018, Kepler was retired after running out of fuel. During its time in orbit around our planet, it confirmed for the first time that we were not alone in the universe.
Worlds outside our own
Finding an exoplanet requires extremely sensitive light-detection instruments and a lot of patience. Kepler was armed with both of those things. To find an exoplanet, the space telescope kept its sensors peeled for slight fluctuations in the light from any of the 150,000 stars in its field of view.
Ever-diligent, Kepler spotted 4,755 potential exoplanets, 2,327 of which have been confirmed so far. The exciting discovery drove NASA to commission a series of retro-style travel posters advertising some of these sci-fi homes away from home.
What it takes to make a home
For a planet to qualify as a potential candidate for life as we know it, a planet must be in the perfect orbit. Too close and it’ll be too hot. Too far away and it’ll be too cold. The “Goldilocks Zone” is the orbital region around a star where the temperature is just right. Another key factor is the presence of a solid or liquid surface, as opposed to a dense, gaseous atmosphere like Jupiter’s.
The discovery of thousands of planets within our own galaxy has led astronomers to conclude that nearly every star in every galaxy is likely to have at least one planet orbiting it, which means that the possibility of life existing outside our solar system is extremely high.
It all comes down to time
While we may not be alone in the universe, there is one tiny detail that could complicate our plans to meet our galactic neighbors, should we ever find them. In the grand scheme of things, our civilized society is brand new and has barely existed for any time at all.
The chances of finding another advanced civilization within traveling distance of us are slim, but we can keep holding out hope that someday, our sci-fi dreams might become a reality.