William Wallace Campbell

Chronicled events

1. May 1909​·​No Planet inside Mercury’s Orbit
   #5755

   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.

2. August 21, 1914​·​War and Clouds Stop the Eclipse Expeditions
   #5757

   Clouds covered the Sun during the eclipse, so we couldn’t measure how much the starlight was bent.