What Can We Actually Find on an Exoplanet? Part 1: The Atmospheric Fingerprint

• In 1990, the Voyager 1 spacecraft captured a picture of Earth, a single pale blue dot, from six billion kilometers away.
• The article discusses how an alien species might use transit spectroscopy to detect life on exoplanets, relying on the tiny signals from a planet's atmosphere.
• The James Webb Space Telescope, launched in 2021, is designed to study planetary atmospheres but is not specifically aimed at finding life.
• The article highlights that detecting biosignatures like oxygen, ozone, methane, and water requires looking for disequilibrium, where these gases coexist in an unusual way, indicating life on Earth.
• The James Webb can detect signals as low as 10 parts per million, which is too faint for Earth-like planets around Sun-like stars.
• The telescope has a better chance of detecting signals from a rocky planet around a small red dwarf star, where the atmosphere blocks more light, increasing the signal.
• The article concludes that finding life elsewhere is difficult, as most exoplanets are likely uninhabitable, and the James Webb has limited chances to detect biosignatures.

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