- Arthur Eddington (1882-1944)
- Born in England.
- He showed that in a normal star, gravitation and radiation pressure balance each other.
- He also showed that the life-story of a star depends upon its original mass.
- Measurements that he made during a total eclipse of the sun confirmed Einstein’s theory of relativity.
- Born in Greece.
- He calculated the lengths of the seasons, starting from the summer solstice, to be ninety days, ninety days, ninety-two days, and ninety-three days, respectively.
Euctamon (fl. ca. 450 BCE)