What is the speed of light?

The answer to this question was discovered 340 years ago by one of the great astronomers, on December 7, 1676. Google marked the 340th anniversary of the great discovery with fascinating Google Doodle today.

The speed of light was discovered by a Danish astronomer called Ole Romer. Before Romer, the famous astronomer, physicist and mathematician Galileo Galilei also tried to measure the speed of light. While the Galileo failed to determine the speed of light, Ole Romer succeeded.

To celebrate the discovery of the speed of light by Ole Romer, Google came up with an animated Google Doodle which depicts what led the astronomer to the historic discovery.

Today’s Google doodle shows how the study and the discovery came into being.

Roemer began his research decades later in 1673 when he noticed the time elapse between the eclipses of a Jupiter moon called Io, which Galileo had discovered in 1610.

By monitoring the time difference, Roemer estimated light seems to take about 10 to 11 minutes to cross a distance equal to the half-diameter of the Earth’s orbit around the Sun. This means that light travels at about 200,000,000 meters per second, which is around 26 % below the established speed.

The Royal Observatory in Paris, for whom Romer was doing research works, wasn’t convinced with his conclusions. When other philosophers of the period, such as Christiaan Huygens and Isaac Newton backed the theory, it started gaining support.

It was finally confirmed nearly two decades after Romer’s death when English astronomer James Bradley in 1728 discovered the “aberration” of starlight and a speed of 295,000,000 meters per second for light