Last year, astronomers discovered an unusual Earth-size exoplanet they believe has a hemisphere of molten lava, with its other hemisphere tidally locked in perpetual darkness. And at about the same time, a different group discovered a rare small, cold exoplanet with a massive outer companion 100 times the mass of Jupiter.

Astronomers have achieved a breakthrough in planetary science, revealing the complex weather of a distant gas giant with unprecedented detail. By mapping the three-dimensional structure of the planet’s atmosphere,