Understanding the Concept
* Eclipses of Jupiter's Moons: Roemer observed that the times of eclipses of Jupiter's moons appeared to vary slightly depending on the Earth's position in its orbit around the Sun.
* The Delay: When Earth was farther from Jupiter, the eclipses seemed to occur later than expected. Roemer attributed this delay to the extra time light took to travel the greater distance.
Calculations
1. Time: The extra time light took to travel the greater distance was 16.5 minutes.
* Convert minutes to seconds: 16.5 minutes * 60 seconds/minute = 990 seconds
2. Distance: The additional distance light traveled was the diameter of Earth's orbit around the Sun, approximately 300,000,000 km.
3. Speed: Speed is calculated as distance divided by time:
* Speed = 300,000,000 km / 990 seconds
* Speed ≈ 303,030 km/s
Roemer's Deduction
Roemer deduced that the speed of light was approximately 303,030 km/s. While this value is slightly higher than the modern accepted value of 299,792 km/s, it was a groundbreaking discovery for its time.
Important Note: Roemer's measurements were impressive for their time, but they were limited by the accuracy of astronomical observations and the understanding of the solar system. His method provides a good conceptual understanding of how the speed of light was first estimated.
