Understanding Kepler's Law
Kepler's Law was discovered by a mathematician who was also a German astronomer named Johannes Kepler (1571-1630). His discovery was based on data observed by Tycho Brahe (1546-1601), a famous astronomer from Denmark.
Before the discovery of this law, ancient humans embraced geocentric understanding, which is an understanding that justifies that the earth is the center of the universe. This assumption is based on limited human sensory experience, which is every day
watching the sun, moon and stars move, while the earth feels silent. This assumption was developed by the Greek astronomer Claudius Ptolemy (100-170 AD) and survived for up to 1400 years. According to him, the earth is at the center of the solar system. The sun and planets circle the earth in a circular path.
Then in 1543, a Polish astronomer named Nicolaus Copernicus (1473-1543) invented the heliocentric model. Heliocentric means that the earth and other planets surround the sun in a circular path.
Of course this opinion is better than the previous opinion. However, there is something still lacking from Copernicus's opinion that silence still uses circles as a form of trajectory of planetary motion.
In 1596 Kepler published his first book in the field of astronomy with the title The Mystery of the Universe. In that book he explained the shortcomings of the two models above namely there is no harmony between the trajectories of planetary orbits with observational data of Tycho Brahe.
Therefore Kepler left the Copernican model as well as Ptolemy and sought a new model. It was only in 1609 that an orbital shape was found that matched Brahe's observational data, the elliptical shape. Then his findings were published in his book entitled Astronomia Nova which was also accompanied by his second law. While Kepler's third law is written in Harmonices Mundi, published ten years later.
The Function of Kepler's Law
The function of Kepler's law in modern life is to estimate the trajectories of planets or other space objects orbiting the Sun such as asteroids or outer planets that have not been discovered during Kepler's life. This law also applies to other orbitals besides the sun.
Like the moon orbiting the earth. Even today, using the basis of Kepler's law, a new object orbiting the earth is found besides the moon. This object is an asteroid measuring 490 feet (150 meters) dubbed the 2014 Asteroid OL339.
Asteroids are close enough to the earth that they look like satellites. The asteroid has an elliptical orbit. It takes 364.92 days to circle the Sun. Almost the same as the earth which has a period of 365.25 days.