An artist’s concept depicts the dividing line between day and night on WASP-39b, a gas giant planet in a star system about 700 light-years from Earth. Telescopes in space and on the ground measured the day and night sides of the planet, finding a temperature difference of about 300 degrees Fahrenheit (200C) between the morning and evening. The morning portion of the planet is also cloudier than the nightside. The planet is larger than Jupiter, the giant of our own solar system, but only about as massive as Saturn, the second-largest planet. That suggests that WASP-39b is puffed up by heat from its star, making it especially fluffy. [NASA/ESA/CSA/R. Crawford (STScI)]