Shape shifter

Look: "Puffy" planets could solve a longstanding exoplanet mystery

Are Mini-Neptunes just giant Super-Earths?

W. M. Keck Observatory/Adam Makarenko

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To get a grasp on the size of exoplanets, researchers often compare them to familiar bodies in the Solar System.

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Mini-Neptunes, for example, describe bodies that are larger than Earth but smaller than Neptune.

They typically contain rocky cores and puffy, gaseous atmospheres — not unlike actual Neptune itself.