Planetary symbols

Planetary symbols are special signs used to represent planets, the Sun, and the Moon. These symbols have been important in astrology and were also used in old astronomy. They came from Greco-Roman astronomy and were later used in alchemy to stand for the seven metals known to the ancients, which were thought to be connected to the planets. Each symbol was also linked to a day of the week in calendars.

These symbols were created a long time ago, and as new planets were discovered, new symbols were made for them. Today, the International Astronomical Union suggests using letters instead of these old symbols in science writing, but the symbols are still interesting to many people.

Some of these symbols, like those for Venus and Mars, are still used today in biology. They were used by Carl Linnaeus in the 1700s to show female and male, and this tradition continues.

History

Classical planets

Main article: Classical planet

Planetary symbols started as ways to show the traits of ancient gods linked to the planets. Early pictures from the 2nd century show gods with special items: Mercury with a staff and hat, Venus with jewelry and a mirror, Mars with armor and a spear, and so on. These ideas later turned into simple written signs used in old books and horoscopes.

Over time, these signs changed and got more detailed. By the 1500s, they looked much like they do today. These symbols were also used in old chemistry for metals linked to the planets and to show days of the week on clocks.

Classical planets

Further information: Classical planets and Days of the week

The symbols for the classical planets have been used for thousands of years in astrology and astronomy. These symbols represent the Sun, the Moon, and the known planets of ancient times. They were also used in alchemy and to name the days of the week.

The Moon is represented by a crescent shape, which has been used since ancient times. The symbol for Mercury is a staff with two snakes, known as a caduceus. The Venus symbol looks like a circle with a small cross below it and is used to represent the female sex. The Sun is shown as a circle with a dot in the center. The Mars symbol, which looks like a shield and spear, represents the male sex. The Jupiter and Saturn symbols are based on the Greek letters for their names.

Modern discoveries

Uranus

The symbols for Uranus were created after its discovery in 1781. One symbol, ⛢, combines the alchemical symbols for iron and gold to represent the metal platinum. Another symbol, suggested in 1784, features the first letter of the discoverer's name. Astronomers usually use the platinum symbol, while astrologers prefer the monogram.

Neptune

When Neptune was discovered, several symbols were proposed. The most common symbol today is Neptune's trident, which can be styled in two different ways. The planet was named after the Roman god Neptune, and its symbol reflects this mythology.

Pluto

Pluto was considered a planet from its discovery in 1930 until 2006, when it was reclassified as a dwarf planet. Its original symbol was a monogram of the letters P and L. Astrologers often use a bident with an orb, which is also used by NASA.

Minor planets

In the 1800s, people used special symbols to represent big rocks in space called asteroids, like 1 Ceres, 2 Pallas, and 3 Juno. These symbols looked like tools or objects related to the asteroid's name. Later, in the late 1900s, new symbols were made for more newly found space objects, including 4 Vesta and 2060 Chiron. Today, symbols for even more distant objects, called dwarf planets, have been created and are used in computers thanks to a system called Unicode.

Many old symbols were made for newly found asteroids between 1845 and 1855, but they were later replaced by simple numbers to make things easier. These old symbols showed different ideas and stories from mythology, like goddesses with tools or animals.