The planets in the solar system have nicknames based mainly on appearance, and also due to their physical makeup or the times at which they can be seen from Earth. Some of the common nicknames include "Red Planet" for Mars and "Evening Star" for Venus.
According to NinePlanets.org, humans have known about several of the planets since prehistoric times, particularly Venus, Mars, Jupiter, and Saturn; this is because they are the planets closest to Earth and are often bright and easily visible.
Mars was named after the Roman god of war because of its red color; it is still referred to as the "Red Planet." Venus is one of the brightest objects in the sky, other than the sun and moon, and it is often referred to as the "Morning Star" and the "Evening Star." Venus was named after the Roman goddess of beauty.
Jupiter, the largest planet, is sometimes referred to as "The Wandering Star" due to its wide orbit. When scientists learned more about its size and makeup, Jupiter started being referred to as the "giant planet" or the "gas giant,"even though other larger planets beyond the asteroid belt are composed of gas. Saturn, the second-largest planet, is another gas giant, but it is most known for its rings and therefore called "The Ringed Planet," according to SolarSystemFacts.net.
Many current or outdated nicknames of planets correlate with their official names; as in the case of Neptune, a blue planet named for the Roman god of the sea, and Mercury, a quickly orbiting planet named after the Roman messenger god.