How far the Earth is from the Sun? This apparently simple question is actually a matter of dispute scientists for over a hundred years.
How to solve a specific point on the Earth to measure? How to determine what distance from the Sun to calculate - up of vapor or flames?
Astronomical unit - a unit of distance in astronomy, which is approximately equal to the average distance from Earth to the Sun, was first calculated by the astronomer and engineer Giovanni Cassini in 1672. He compared his measurements on Mars, with the observations of his colleague Jean Richer, helping them determine the value of the third - the distance between the Earth and the Sun is 146 million kilometers.
But in fact, this number is a parallax - a combination of constants that convert angular measurements in the distance.
For ordinary mortals, according to a recent decision of the International Astronomical Union, the astronomical unit is equal to 149 597 870 700 meters.
For us, this decision will not be a revolution in life, but for astronomers a fixed value means greater convenience in calculating distances.