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William Wallace Campbell addressed criticism #5754.
#5754·Urbain Le VerrierHistorical profile, September 12, 1859·AI-assistedNewton’s law isn’t wrong. Unseen matter inside Mercury’s orbit, a planet or a ring of small bodies, would explain the difference. That’s how the unseen Neptune explained the odd motion of Uranus.
Photographs from the eclipses of 1901, 1905, and 1908 show no planet inside Mercury’s orbit big enough to explain its motion. Whatever moves Mercury’s perihelion, it isn’t a planet, or anything else bright enough to photograph.