It was months and years of difficult geometrical calculations from measurements made by Tycho Brahe, by his employee Johannes Kepler.
When Tycho was alive he would not let Kepler see the results of his work, but he let slip a few figures, tantalisingly, now and again. But after Tycho's death Kepler was clever and devious enough to get his hands on the results, which was fortunate because he had the ability to make use of them.
Kepler chose the orbit of Mars as a special subject, which was lucky because it has a relatively high eccentricity that shows up the difference between an ellipse and a circular orbit. After some false starts he realised that the figures fitted an elliptical orbit. Subsequently further observations demonstrated that elliptical orbits gave correct predictions of the positions of Mars and the other planets.
Kepler used the heliocentric principle, with the Sun at the centre. Although Kepler and Galileo were contemporary, Galileo never believed that the planets' orbits could be elliptical, and he stuck to the old systems of circles and epicycles of Ptolemy and Copernicus.
Johannes Kepler with his 3 laws of planetary motion.
Johannes Kepler was the first to state that planets move in elliptical orbits.
All planets actually follow an elliptical orbit.
The ancient Greeks used Ptolemy's theory, based on circles, that was good enough for the accuracy needed at the time. Later Kepler in the 16th century discovered that an ellipse is a better model of a planetary orbit. In modern times it has been discovered that an ellipse is an approximation and that true orbits have no simple description. But the ellipse is a good enough model for many purposes.
Scientist know this by the color difference on the planets surface.
Scientist discovered tectonic plates
Kepler
Johannes Kepler was the first to state that planets move in elliptical orbits.
The scientist who discovered that atoms have an energy level is Niels Bohr in 1913. According to his model electrons move around the nucleus much the same as the planets rotate around the sun.
All planets actually follow an elliptical orbit.
Planetary orbits are usually in the shape of an ellipse.
Johannes Kepler.
The ancient Greeks used Ptolemy's theory, based on circles, that was good enough for the accuracy needed at the time. Later Kepler in the 16th century discovered that an ellipse is a better model of a planetary orbit. In modern times it has been discovered that an ellipse is an approximation and that true orbits have no simple description. But the ellipse is a good enough model for many purposes.
The person who first stated this was Johannes Kepler.
Copernicus
It is Kepler's first law which says the planet moves in an ellipse with the Sun occupying one focus and the other focus is vacant.
Johannes Kepler in his three laws of planetary motion
Closer to the sun.