Our circumstances here on the wondrous, life-supporting Earth can give us a false understanding of what the Universe is really like. But our blue-skied, temperate planet is the extreme exception when it comes to other worlds. There's nothing remotely like Earth in our Solar System, and exoplanet studies reinforce that idea. While some exoplanets have hints of habitability, most exoplanets are extremely inhospitable.

Ultra-Short Period (USP) planets are one example of these hostile worlds. USPs follow orbits shorter than one Earth day long, meaning they're very close to their stars. They're so close that their surfaces are molten, and they've likely lost whatever atmospheres they had to their star's intense output. These planets are also imperiled: they can be torn apart by their stars' massive gravitational force, or even spiral into their stars and be totally destroyed.