The closest star to our Sun, Proxima Centauri, lies approximately 4.25 light-years away. A light-year is the distance light travels in one year—about 9.46 trillion kilometers—at a blistering 300,000 kilometers per second. That makes the journey to Proxima roughly 40 trillion kilometers, a gulf so immense that no human spacecraft has come close to bridging even a tiny fraction of it. Voyager 1, launched in September 1977 (now over 48 years ago), remains humanity's farthest-reaching probe. Traveli

Potentially habitable exoplanet candidate spotted around Alpha Centauri A in Earth's backyard