John H. Livingston

The three planets in the Kepler-51 system have long intrigued astronomers: they are Saturn-sized but less dense than water. These 'super-puff' worlds, with masses no more than ten Earths, are like cosmic dandelions — massive yet almost weightless. Their orbits are arranged like musicians in an orchestra, each playing its part, beating the rhythm with transits.

350 light-years away, four planets orbit the star V1298 Tau. They are 5–10 times larger than Earth but lighter than they appear. For nine years, astronomers tracked their motion to understand what they are made of and how they lived in the past. The planets are lined up in a chain: their orbital periods are nearly in 3:2, 2:1, and 3:1 ratios.

Astronomers using the JWST (James Webb Space Telescope) have for the first time studied in detail the atmosphere of a young exoplanet, V1298 Tau c. This super-Earth, a planet more massive than Earth but less so than gas giants, is only 23 million years old.

A planet glides across a star's disk, and for a moment becomes a flashlight. It blocks a tiny patch of surface, revealing details that otherwise escape our view. That's exactly how astronomers peered into the dark spots on V1298 Tauri, a young twin of our Sun. They were aided by the James Webb Space Telescope JWST and three giant planets in orbit.