When humans began farming, they needed a reference to identify planting and harvesting times.

Looking at the sky, our ancestors noticed that some stars describe a regular movement, which gave them a sense of time and times of the year.

First, it was concluded that the sun and the other observed planets revolved around the earth. But this model, called the Geocentric Model, had several flaws that encouraged the study of this system for thousands of years.

Around the 16th century, Nicholas Copernicus (1473-1543) presented a Heliocentric model, in which the sun was at the center of the universe, and the planets described circular orbits around it.

In the seventeenth century, Johanes Kepler (1571-1630) enunciated the laws governing planetary motion, using notes from astronomer Tycho Brahe (1546-1601).

Kepler formulated three laws that became known as *Kepler's Laws*.

## Kepler's 1st Law - Law of Orbits

The planets describe elliptical orbits around the sun, which occupies one of the foci of the ellipse.

## Kepler's 2nd Law - Law of Areas

The segment that joins the sun with a planet describes equal areas at equal time intervals.

## Kepler's 3rd Law - Law of Periods

The quotient of the squares of the periods and the cube of their average distances from the sun is equal to a constant. *k*, equal to all planets.

Given that the translational motion of a planet is equivalent to the time it takes to travel around the Sun, it is easy to conclude that the farther the planet is from the Sun, the longer its translation period will be and, As a result, the bigger your year will be.