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How did the Spitzer Space Telescope study extrasolar planets?
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Telescope
Aerial view of the Keck Observatory's twin domes, which are opened to reveal the telescopes. Keck II is on the left and Keck I on the right.
The Spitzer Space Telescope studied extrasolar planets primarily by detecting the infrared radiation they emitted. Because the central stars around which these planets revolve heat them to temperatures of approximately 1,000 K (700 Ā°C, or 1,300 Ā°F), the planets produced sufficient infrared light for the telescope to observe them directly.12
Using this capability, Spitzer determined the temperature, atmospheric structure, composition, and dynamics of several extrasolar planets. Additionally, the telescope observed the transits of planets, including the seven Earth-sized planets in the TRAPPIST-1 system. By monitoring these transits, astronomers could gather data on the planets' orbital characteristics and atmospheric properties.123