Proxima b is 4.3 light-years away—the distance that light, moving at a hundred and eighty-six thousand miles per second, travels in 4.3 years. That means the Proxima b detectable today is the exoplanet as it existed 4.3 years ago, when those light rays left its surface. Such is the weirdness of space-time that residents of Proxima b could say the same about Earth. If they aimed their radio telescopes our way, they’d find Taylor Swift’s “We Are Never Ever Getting Back Together” climbing up the Billboard charts and Gotye’s “Somebody That I Used to Know” fading away.
Source: An Exoplanet Too Far – The New Yorker
