R. Paul Butler

Jupiter is a colossal ball of gas that sits five times farther from the Sun than Earth. Now imagine a similar ball, but around another star, at a distance tens of times greater. These are called cold Jupiters, and they remain a puzzle: how did they get there? Astronomers studied four such planets around distant stars.

NASA's TESS space telescope monitors thousands of stars, catching the moment when a planet crosses its star's disk — the star's light dims slightly. That's how astronomers spotted two planets orbiting stars similar to our Sun. One, TOI-883 b, completes an orbit in ten days; the other, TOI-899 b, takes nearly thirteen.

A ball, almost weightless for its size, circles its star every four days. Planet TOI-2195 A b is a real riddle: by mass it's slightly heavier than Neptune, yet bloated to Jovian volumes. If there were an ocean big enough, this exoplanet would float on its surface like a giant inflatable ball.