Astrology

Astrology is the system of using the relative positions of celestial bodies (including the sun, moon, and planets) to try to predict future events or gain insight into personality, relationships, and health.

Humans
One human astrological practice was to draw a circular chart, called a personal chart, showing the position of the planets at the time of a person's birth. Creating one was an intensive process, requiring the consultation of timetables, as well as the calculation of angles. Once completed, this chart could be used in combination with data on upcoming planetary movements to work out a personal forecast, called a horoscope.

Astrology was taught in fourth year Divination at Hogwarts School of Witchcraft and Wizardry.

Alchemists, because of the lack of common words for chemical processes as well as the need for secrecy, borrowed terms from astrology and other mystic and esoteric fields.

The Daily Prophet listed current zodiac aspects on its front page starting in 1994. By 1995, it ran horoscopes on the back page, as well as a feature on page six called Astro News, which was presumably dedicated to astrology.

The identity cards of Ministry of Magic employees listed their sun and moon signs rather than their dates of birth.

Centaurs
Like humans, centaurs practiced astrology, but their approach to it was different. While centaurs used astrology only to foresee major, world-changing events, humans also utilized it to predict mundane, day-to-day occurrences and better understand themselves. Centaurs viewed these things as being far too trivial to be affected by the movement of the planets.

According to Firenze, his species spent hundreds of years observing celestial movements, unlocking their secrets and thereby learning to see signs of "great tides of evil or change" to come written in the sky. It could take up to a decade of watching for centaur astrologers to be confidant they knew what they were seeing. Even then, Firenze stressed that one should never place too much trust in such things, as it was possible to misinterpret signs.

Planetary influences

 * Mars — This planet caused burns, accidents, and things of a similar nature according to Parvati Patil. In addition, Parvati claimed that when Mars and Saturn formed a right-angle, it indicated people needed to exercise extra caution when handling hot things. Firenze stated that centaurs interpret Mars shining brightly in the sky as a harbinger of war.
 * Saturn — This planet being in a prominent position at the time of a person's birth was said by Sybill Trelawney to have a "baleful influence," causing dark hair, short height, and tragic losses early in life.
 * Pluto — This planet could disturb day-to-day life in a number of ways according to Trelawney.

Other planets

 * Moon
 * Mafalda Hopkirk — Leo
 * Uranus
 * Lavender Brown — unknown sign, but unaspected

Appearances

 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Deathly Hallows: Part 1

Notes and references
Astrología