If you had X-ray vision — real X-ray vision, meaning you could actually see this type of high-energy radiation — your view of the universe would be vastly different than it is now. Especially if you could sail above the Earth’s atmosphere and stare at the sky. There, all kinds of objects that are normally hidden would suddenly appear.

Alas, humans have not evolved the ability to detect X-rays (or fly); luckily, we’ve built instruments that can. One of the greatest of these is the orbiting Chandra X-Ray Observatory, a space telescope launched 15 years ago today. Carried into Earth orbit by the space shuttle Columbia, Chandra has peered deep into some of the universe’s most mysterious realms —