Answer:
Inner planets orbit the Sun at higher speed than outer planets.
Earth is slightly closer to the Sun on one side of its orbit than on the other side.
Explanation:
Scientist Johannes Kepler (1571–1630) was one of the forerunners in the mathematical treatment of planetary orbit issues.
Kepler's First Law is the law of orbits, which says:
"<em>... all planets move in elliptical orbits with the sun as one of the foci ...</em>"
Kepler realized that the orbital velocity of the planets around the sun was not constant. Because of the shape of the orbits, there were points where the distance to the sun increased or decreased and this change was responsible for variations in the speed of the planets orbiting the sun.
We say that when they reach the shortest distance from the Sun, the planets are in the perihelion and when they reach the point of the farthest orbit, they are in the aphelion.
The following figure shows the positions A and B, which are respectively the perihelion and aphelion of the orbit of the planets around the sun. The X positions are the foci of the ellipse. The sun always coincides with one of the foci of the ellipse.
This is the case with planet Earth, for example, which performs a movement along an elliptical orbit around the sun, although the eccentricity is small so that it can be approximated by a circle depending on the accuracy of the analysis.
