June 21 - July 22
Ruled by Moon · Vedic name Karka
Cancer is the cardinal water sign ruled by Moon, spanning June 21 - July 22 in the Western tropical zodiac. In Vedic astrology it is known as Karka and falls in the sidereal zodiac roughly 24° earlier, and in Hellenistic astrology its strength is judged by Moon's dignity and the chart's sect. This guide reads Cancer through all three traditions, where they agree and where they diverge.
| Attribute | Western | Vedic | Hellenistic |
|---|---|---|---|
| Sign name | Cancer | Karka | Cancer |
| Zodiac | Tropical | Sidereal (~24° earlier) | Tropical |
| Reads ruler by | Modern rulership | Graha + nakshatra | Dignity + sect |
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The Moon, the ruler of Cancer, is the fastest-moving celestial body used in astrology, completing a full cycle through all twelve signs approximately every 28 days. As ruler of Cancer, the Moon expresses its most nurturing, protective, and emotionally attuned qualities. The Moon governs the emotional body, instinctive responses, memory, the mother or primary caregiver, and one's sense of belonging. Unlike the Sun, which represents conscious identity and will, the Moon speaks to what we need to feel safe, how we process feelings, and the patterns of emotional response shaped in early childhood. Understanding the Moon in a birth chart reveals the native's deepest emotional needs and their instinctive way of caring for others.

As a cardinal water sign, Cancer represents the surging tide, the initial rush of feeling that moves one to action on behalf of those they love. Cardinal signs initiate, and water signs deal with emotion, intuition, and the realm of the unseen. Together, cardinal water produces the most actively protective and emotionally initiating expression in the zodiac. This combination gives Cancer its characteristic drive to nurture and its readiness to defend what feels vulnerable. Unlike fixed water (Scorpio), which probes and intensifies, or mutable water (Pisces), which dissolves and transcends, cardinal water moves to shelter, to feed, and to create the conditions for emotional safety.
By Mira, Starwell's resident reader. Placements computed with the Swiss Ephemeris across Western, Vedic, and Hellenistic traditions. Updated June 7, 2026.