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How can we spot exoplanets 20M light years away, but not have absolute metaphysical certitude about the number of planets in the solar system?
by tiahura 3y ago
How can we spot exoplanets 20M light years away, but not have absolute metaphysical certitude about the number of planets in the solar system?
- ivanjermakov 3y agoNot sure where 20M l.y. are coming from, because the farthest exoplaned seems to be 27k l.y. from the Sun: https://en.wikipedia.org/wiki/SWEEPS-11 https://en.wikipedia.org/wiki/SWEEPS-11 Regarding your question, perhaps it's harder to perform direct imaging of a planet in the solar system than of an exoplanet against its local star(s). In the first case, relative motion is much higher.
- vikingerik 3y ago1) We spot exoplanets by their influence on the star, which is nearly nil at distances of 100+ AU. 2) We spot exoplanets that have huge volumes and masses, like Neptune or Jupiter size (15x or 100x Earth's mass, or even multiples of Jupiter), but the ones we're talking about beyond the Kuiper belt might be on the order of 0.1 Earth mass or smaller. 3) 20M light years is an exaggeration, most detected planets are within 1000 light years.