The researchers used Spitzer to determine the temperature variation in the atmosphere of a nearby planet called Upsilon Andromedae b. This "hot-Jupiter" planet is a gas giant similar to Jupiter, but it orbits very close to its scorching star, circling the star once every 4.6 days. Scientists believe the planet is tidally locked to its star. This means it is rotating slowly enough that the same side always faces the star, just as the same side of Earth's tidally locked moon always faces toward us, hiding its "dark side." However, since this planet is made of gas, its outer atmosphere...