You know you're a Cancer. Do you know which Cancer you are?

What is a Cancer really like?

Cancer is the fourth sign of the zodiac: a water sign, a cardinal sign, ruled by the Moon. The Sun is in Cancer from June 21 or 22 to July 21, 22 or 23. What any one Cancer is really like depends on the rest of the chart: the Moon, the rising sign, Venus and Mars.

Cancer is one of twelve. What is the zodiac, and where did the twelve signs come from?

What it is

Your sun sign is the slice of the zodiac the Sun was standing in on your birthday. The zodiac here is a measuring tape, not a picture: the Sun's yearly path cut into twelve equal slices of 30°, counted from the spring equinox. Cancer is the fourth slice, and the Sun crosses it from June 22 to July 22. ¹

It isn't the constellation. When the Babylonians matched twelve star patterns to twelve equal slices, the dates and the stars lined up. Earth's axis has wobbled since, so on the same dates the Sun now stands in front of different stars, and astronomers count thirteen constellations on its path, not twelve. Western astrology keeps its slices tied to the seasons, not to the stars. ¹

Cancer is a water sign and a cardinal sign. Ptolemy grouped the signs in triangles of three, 120° apart; Cancer's triangle is Cancer, Scorpio and Pisces, the one later astrologers called water. The modes come from the seasons: cardinal signs fall in the first month of a season, when it turns. ²

A ruling planet is the planet a sign is said to belong to, its "house" in Ptolemy's word. Tradition gives Cancer to the Moon. ²

A sun sign is one placement out of many. The Moon, the rising sign and every planet sit in signs of their own, which is why two people with the same sun sign can seem to have very little in common.

This is the short version for one sign. How the zodiac was built, and its whole history, is on the master page: What is the zodiac, and where did the twelve signs come from?

Cancer in the old books

The traditional portrait of the sign, the same for everyone born under it.

Cancer, in the old books, is the Moon's own house, and one of Ptolemy's two solstitial signs, where the Sun stops climbing and turns back at midsummer. The portrait is all shell and tide: protective, sentimental, tied to home and family, with a memory that keeps everything, birthdays and grudges alike. ²

The old writers' caution is moodiness. The Crab is said to go sideways rather than straight at a problem, to sulk in its shell and come out only when it feels safe. The cardinal mode, they say, gives it more push than the soft reputation lets on: Cancer opens summer, and it starts things, quietly, at the kitchen table.

That's every Cancer, read from the Sun. A fiery rising sign or a bold Mars can put a very different face on the same Crab.

Where Cancer comes from

Era by era, with sources. More in the Reading Room.

Ancientc. 1000–450 BCEBabylonian astronomers built the zodiac out of eighteen reference star groups over about a thousand years; by around 450 BCE it had settled into twelve equal zones along the path of the Moon and planets. ³
Ancient419 BCEThe Crab is already in the first known list of all twelve signs, a Babylonian text dated 419 BCE. Late Babylonian texts call it Alluttu. ^4,5
Ancient410 BCEThe earliest known horoscopes, from Babylon and Nippur, date to this year. ³
ClassicalRoman eraPseudo-Hyginus (2.23) says Juno put the Crab among the stars. While Hercules fought the Hydra, it nipped his foot from the swamp; he killed it, and Juno gave it a place in the sky. ⁶
Classical2nd century CEPtolemy, working in Alexandria, writes the Tetrabiblos. It gives each sign a ruling planet, groups the signs in triangles of three and sets out the angles between signs that astrologers still use. ^7,2
Classical2nd century CEPtolemy names Cancer and Capricorn the solstitial signs and gives Cancer to the Moon. His map of the world ties it to Numidia, Carthage and Africa, and to Bithynia and Phrygia. ^2,8
Medieval12th centuryThe Persian astrologer Abu Ma'shar (died 886) is read in Latin across Europe; the University of Edinburgh holds a 12th-century Latin copy of his introduction to astrology. ⁹
Medievalc. 1464In the zodiac man of an English doctor's folding almanac (Morgan Library), Cancer governs the breast. ¹⁰
1800s1890The first number of Alan Leo's Astrologer's Magazine goes on sale in July 1890. Annual subscribers get a free horoscope with a short reading: astrology by post, for ordinary readers. ¹¹
1910s1917Alan Leo is fined for fortune-telling at the Mansion House on 16 July 1917. He dies that August, working on a system of astrology without predictions. ¹¹
1930s1930–1937R. H. Naylor's horoscope for the newborn Princess Margaret runs in the Sunday Express on 24 August 1930 and becomes a regular column. By 1937 it is organised by the twelve sun signs, and newspapers on both sides of the Atlantic follow. ¹²
1960s1968Linda Goodman's Sun Signs is published: a whole book built on the twelve sun signs. ¹³
1980s–90s1980–1999Computers take over the arithmetic. Astrodienst in Zürich, whose founder had been writing astrology software since 1979, starts selling colour birth charts in 1980, goes online in 1996 and adds free daily horoscopes in 1999. ¹⁴
2010s2013NASA's Astronomy Picture of the Day explains the Tropic of Cancer's name: the Sun used to stand in Cancer at the June solstice. The slow wobble of Earth's axis has since moved it into Taurus, though the line kept the Crab's name. ¹⁵
2010s2016NASA publishes a short explainer: the Sun crosses thirteen constellations, the Babylonians picked twelve to fit a twelve-month calendar, and "we didn’t change any zodiac signs". ¹
Today2024A Pew Research Center survey finds that 30% of US adults consult astrology, tarot or a fortune teller at least once a year, mostly for fun, with whole astrology cultures on TikTok and other platforms. ¹⁶

Worked out, not guessed

Calculated facts only, worked out the same way the machine does it.

Venus never gets more than about 47° from the Sun, so a Cancer's Venus is always in one of five signs: Taurus, Gemini, Cancer, Leo or Virgo.
The Moon changes sign every two and a half days. Without a birth time and place, most birthdays could belong to either of two Moon signs. (91.1% of birthdays from 1950 to 2029, once every time zone on Earth is allowed for.)

Every Cancer reads this page. Only your card knows you.

Your card is worked out from the day, the minute and the place you were born: your birth chart, your love chart, your numbers and the sky you arrived under. This is what it covers.