The Kepler telescope has generated excitement among astronomers by identifying hundreds of exoplanets -- planets beyond our solar system. Most of these planets don't have conditions suitable for life, but a few probably do. Unfortunately, astronauts won't be traveling to any of them in the foreseeable future. Why? Because the closest one is a few hundred light-years away. A light-year is about 5.9 trillion miles, so the planets that Kepler is finding are much too far away to get to using conventional spacecraft.
The closest star to our solar system, just 4.37 light-years away, is Alpha Centauri. Astronomers have used computer simulations to show that rocky planets could form around Alpha Centauri, so perhaps it will be a reasonable place to visit. Even if direct observation reveals an Earth-like planet, the journey would take a long, long time.
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