This is an artist's impression of the Jupiter-size extrasolar planet, HD 189733b, being eclipsed by its parent star. Astronomers using the Hubble Space Telescope have measured carbon dioxide and carbon monoxide in the planet's atmosphere. The planet is a "hot Jupiter," which is so close to its star that it completes an orbit in only 2.2 days. The planet is too hot for life as we know it. But under the right conditions, on a more Earth-like world, carbon dioxide can indicate the presence of extraterrestrial life. This observation demonstrates that chemical biotracers can be detected by space telescope observations.
NASA's James Webb Space Telescope will have many tricks up its sleeve when it comes to looking into the atmospheres of gas giants orbiting other stars.
Webb can directly observe how a planet’s atmosphere strips certain colors out of the starlight passing through it using spectrometry: molecules in the atmosphere absorb different parts of the electromagnetic spectrum, leaving clues to their presence.
Webb can indirectly observe a planet’s contribution to starlight by watching what changes when the planet passes behind its star. This will give clues to what’s happening on the day side of the planet.
Using something called a phase curve — the changes in reflected or refracted light throughout a planet’s orbit — Webb can look for dynamic processes such as weather patterns.
Ultimately, astronomers want to use Webb to study potentially
habitable planets. In particular, Webb will target planets orbiting
red dwarf stars because those stars are smaller and dimmer, making it
easier to tease out the signal from an orbiting planet. Red dwarfs are
also the most common stars in our galaxy.
However, astronomers will target easier, gas giant exoplanets first.
Credits: ESA, NASA, M. Kornmesser (ESA/Hubble), and STScI
NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission.
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