After all, “seeing is believing” is a very human prejudice. But imaging a distant planet is a formidable challenge indeed. Suppose, for example, you were a great distance away and wished to detect reflected light from Earth. Earth intercepts and reflects less than one billionth of the Sun’s radiation, so its apparent brightness in visible light is less than one billionth that of the Sun. Compounding the challenge of detecting such a faint speck of light, the planet is swamped by the blaze of radiation from its parent star.
Direct Detection
The best possible evidence for an earthlike planet elsewhere would be an image.
Source & attribution
Astronomy 2e — Planets beyond the Solar System: Search and Discovery
OpenStax contributors · OpenStax, Rice University
CC BY 4.0. Text excerpted; whitespace normalised and empty cross-references removed; learning prompts added. No illustrations reproduced.
Source edition: 2024-10-17T15:19:16Z
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