What can Earth tell us about exoplanets?
The closest exoplanet, Proxima Centauri b, is more than 20 trillion miles away — and we can't get to it. Using today's technology, it would take a spacecraft 75,000 years to arrive there. But we try to understand these distant worlds by using Earth as our model of a habitable world; it's the only example we have after all. Exoplanetary scientists study the evolution and dynamics of Earth's atmosphere and the impact of geological and biological processes on its environment. The rich data we have about Earth is used to validate our exoplanet models, which make predictions that observatories will be able to test. But, just as Earth guides our understanding of exoplanets, exoplanets can teach us about our home planet. Young exoplanets could shed light on processes that shaped Earth and other planets in our solar system billions of years ago. Older exoplanets, meanwhile, could help us prepare for the conditions Earth may face in the distant future.