Cancer
Cancer is the fourth sign of the tropical zodiac, covering the 90°–120° sector starting at the March equinox, between June 21 and July 22. Its start marks the June solstice, the astronomical beginning of summer in the Northern Hemisphere. It is a Water sign, Cardinal in modality, ruled by the Moon.
Last reviewed: 2026-07-19
Historical fact
In ancient Babylonian astronomy (recorded in the MUL.APIN compendium, around the 7th century BCE), the sky sector now known as Cancer was called AL.LUL, a crab or crayfish figure. Greek myth reattributes the sign to the crab sent by the goddess Hera to hinder Heracles during his battle with the Hydra, one of the Twelve Labors — Heracles crushed it underfoot, and Hera placed it among the stars in recognition of its effort. Ptolemy systematized the order of the twelve signs, including Cancer as the fourth, in the Tetrabiblos, around 150 CE, also fixing its start at the June solstice.
Interpretation — Western Astrology (Tropical)
In modern Western astrology, Cancer is read as the sign of home and emotional care: Cardinal energy (which, in this case, opens the inward-turning half of the seasonal cycle) combined with the element Water (emotion, intuition) under the rulership of the Moon, associated with instinct, memory and emotional bonds. Commonly associated traits: emotional sensitivity, a capacity to nurture and care for others, strong attachment to family and home, and vivid emotional memory. The shadow side commonly includes mood instability, excessive attachment to the past, and defensiveness in the face of perceived threats.
Interpretation — Vedic Astrology (Sidereal)
In the Vedic system (Jyotish), the corresponding sign is Karka, also ruled by the Moon (Chandra) and likewise the fourth of the twelve rashis. Because it uses the sidereal zodiac, which accounts for the precession of the equinoxes, Karka's date window is currently shifted relative to tropical Cancer — today falling roughly from mid-July to mid-August, varying by the ayanamsa (calculation method) used. Classical texts such as the Brihat Parashara Hora Shastra describe Karka natives as emotionally sensitive, devoted to family and home, with a strong protective instinct — a characterization broadly convergent with the Western reading, despite the two systems developing independently.
This section presents one tradition's interpretation, not a verifiable fact.
Frequently asked questions
- Why does Cancer's start coincide with the June solstice?
- Because the tropical zodiac is organized around the points that mark the seasons: Cancer begins exactly at the June solstice, the moment the Sun reaches its northernmost position, marking the astronomical start of summer in the Northern Hemisphere.
- Where does Cancer's crab symbol come from?
- It already appeared in Babylonian astronomy as AL.LUL, a crab or crayfish figure. Later Greek myth associated it with the crab sent by Hera to hinder Heracles in his fight against the Hydra, being placed among the stars after being crushed.
- Are Cancer and Karka (Vedic) the same sign?
- They correspond to the same position in the sequence (fourth sign, ruled by the Moon), but occupy different date windows, because the Vedic zodiac is sidereal (aligned to the constellations) while the Western zodiac is tropical (aligned to the seasons) — the gap today is roughly 24 degrees.
Sources
- Nicholas Campion. A History of Western Astrology (2009).
- Claudius Ptolemy. Tetrabiblos (c. 150).
- Maharishi Parashara (trans. R. Santhanam). Brihat Parashara Hora Shastra (1984).
- David Pingree. From Astral Omens to Astrology: From Babylon to Bīkāner (1997).