Astronomers have created signs for the planets, like a kind of hieroglyphic shorthand. Most of these symbols are linked to the planets’ names or their history in some way.
Mercury’s symbol is linked to the Roman god it was named after – the winged messenger of the gods. The planet’s symbol is supposed to represent Mercury’s helmet and caduceus – a herald’s staff with snakes and wings intertwined.
Venus’ symbol has more than one meaning. Not only is it the sign for “female”, but it also represents the goddess Venus’ hand mirror. This representation of femininity makes sense considering Venus was the goddess of love and beauty. The symbol is also the chemical sign for copper; copper was used to make mirrors in ancient times.
Earth’s sign also has a variety of meanings, although it does not refer to a mythological god. The most popular view is that the circle with a cross in the middle represents the four main compass points. It has also been interpreted as the Globus Cruciger, an old Christian symbol for Christ’s reign on Earth. This symbol is not just limited to Christianity though; it has been used in various culture around the world including showing up in Norse mythology.
Mars is named after the Roman god of war, so it is no surprise that the planet’s symbol refers to that. The sign represents Mars’ shield and spear. Additionally, it is the same sign as the one used to represent “male.”
Jupiter’s sign, which looks like an ornate, oddly shaped “four,” also stands for a number of symbols. It has been said to represent an eagle, which is Jupiter’s bird. Additionally, the symbol can stand for a “Z,” which is the first letter of Zeus who was Jupiter’s counterpart. The line through the symbol would indicate that it was an abbreviation for Zeus’ name. The symbol is also supposed to represent Jupiter’s weapon of choice – a lightning bolt.
Like Jupiter, Saturn resembles another character – an “h.” However, this symbol is actually supposed to be Saturn’s scythe or sickle because Saturn is the Roman god of agriculture.
The sign for Uranus is a combination of two other signs – Mars’ sign and the Sun’s symbol – because the planet is connected to these two in mythology. Uranus represented heaven in Roman mythology, and this ancient civilization believed that the Sun’s light and Mars’ power ruled the heavens.
Neptune’s sign is linked to the sea god Neptune, who the planet was named after. The symbol represents the sea god’s trident.
Although Pluto was demoted to a dwarf planet, it still has a symbol. Pluto’s sign is a combination of a “P” and a “L,” which are the first two letters in Pluto as well as the initials of Percival Lowell, the astronomer who discovered the planet.
Astronomy Cast has an episode on each planet including Saturn.