The Speed of Light
Ole Roemer found that Jupiter’s moons are eclipsed by the planet about 16 minutes earlier when the Earth is closest to Jupiter (position 1) than when it is furthest (position 2)
Explanation? Newton’s laws wrong?
- No. Light has a finite speed. When Jupiter is further from the Earth, it takes a longer time for the information about the eclipse to reach the Earth.
- Quantitative estimate:
c = Speed of light = (diameter of Earth’s orbit / 16 minutes)
= 190,000 miles/second.
Impressive! --- the accepted value now is 186,000 miles/sec