They are dull bodies that are capable of reflecting light and revolve around the Sun in elliptical orbits (Escobar, 2007). Their name comes from the Greek “planēt-”, that literally means “wanderer”. Since 2006, the International Astronomical Union (IAU) agreed not to consider Pluto as a planet, but as a dwarf planet. Therefore, nowadays there are eight planets in the Solar System: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.