Cracking the Code of Faraway Worlds

A CLOSER LOOK

This infrared data from NASA's Spitzer Space Telescope -- called a spectrum -- tells astronomers that a distant gas planet, a so-called "hot Jupiter" called HD 209458b, might be smothered with high clouds. It is one of the first spectra of an alien world. A spectrum is created when an instrument called a spectrograph cracks light from an object open into a rainbow of different wavelengths. Patterns or ripples within the spectrum indicate the presence, or absence, of molecules making up the object. Astronomers using Spitzer's spectrograph were able to obtain infrared spectra for two so-called "transiting" hot-Jupiter planets using the "secondary eclipse" technique. In this method, the spectrograph first collects the combined infrared light from the planet plus its star, then, as the planet

Explore NASA's original image record for credits and available downloads.