Today we celebrate the 340th years since the speed of light was discovered. As we all know, light has the greatest speed of all the things existing in the world. What we may not know is that until the 17th century, people thought that light traveled instantaneously. The man who managed to demonstrate the limitations of the speed of light was Ole Roemer.
We have to acknowledge that Galileo has also tried to demonstrate that light moved at a certain pace, testing his theory by using lanterns flashing from high hilltops. Unfortunately, this test was not enough to prove the theory. Roemer made use of a wider stage to prove his point. Back in 1676, he recorded the intervals between eclipses undergone by Jupiter’s moons at distinct points of Jupiter’s orbit around the sun.
He revealed that the disparity between eclipses of Io, Jupiter’s moon, increased to approximately seven minutes when our planet was distancing from Jupiter. Due to these calculations, Roemer managed to estimate the speed of light. His discovery was not accepted by everybody, especially by Giovanni Domenico Cassini, the director of the Royal Observatory.
Nevertheless, Roemer managed to convince a lot of scientists through his demonstration, including Isaac Newton. Roemer’s theory about the speed of light was demonstrated two decades after he died by astronomer James Bradley. The speed of light was determined to be 299,792,458 meters/second. Every scientist had agreed with the theory in 1975 when the measurements of physicists became even more accurate.
Researchers have also demonstrated that a light-year represents the distance which is crossed by light in one year. The calculations have unveiled that it is about 9.5 trillion km. If a particular source of light is situated far away, we are aware of the fact that light will take a lot of time to reach that point. Astronomers have argued that the most distant celestial object in the universe is a galaxy named MACS0647.
This galaxy is located at approximately 13.3 billion light-years away from us. That means that the light coming from that galaxy had started its journey when our planet was very young, a long time ago. We know that the Sun, our source of light, is situated at approximately 149 million km from Terra. This means that it takes only 8 minutes and 20 seconds for a beam of light to reach Earth.
Image courtesy of: wikipedia