This spectrum describes the hot, Jupiter-like gas giant depicted on slide 4. Using the Spitzer Space Telescope, astronomers compared infrared light from planet and star combined (dark green) with data taken while the planet was in eclipse behind its star (lighter green). They expected to see signs of water but found silicates, suggesting that HD 209458b might be blanketed in dust clouds. Oxygen and carbon have since been detected in this world's atmosphere--a first.