What it looks like
Cancer is one of the faintest zodiac constellations, a small Y-shaped pattern of dim stars in the northern celestial hemisphere. At its centre sits the Beehive Cluster (M44), a naked-eye open cluster that has been observed since antiquity.
Brightest stars
Cancer has no first- or second-magnitude stars; its brightest, Al Tarf, only reaches magnitude 3.5.
| Star | Magnitude | Distance | Meaning |
|---|---|---|---|
| Al Tarf (β Cancri) | +3.53 | 290 ly | The Glance |
| Asellus Australis (δ Cancri) | +3.94 | 136 ly | Southern Donkey |
| Asellus Borealis (γ Cancri) | +4.66 | 181 ly | Northern Donkey |
| Iota Cancri | +4.02 | 298 ly | — |
Mythology and history
In Greek myth, Cancer is the crab that Hera sent to distract Heracles during his battle with the Hydra, and which he crushed underfoot.
The crab of Lerna
While Heracles fought the many-headed Hydra, Hera sent a giant crab to pinch his heel and hinder him. Heracles crushed it, and Hera rewarded its loyalty by placing it in the sky. Though the crab played a minor role, its constellation sits between Leo and Gemini along the ecliptic.
Older associations
Ancient Egyptians and Babylonians linked this region to the scarab beetle and to a gateway of souls descending through the sky.
How to find it
Look between Leo and Gemini, roughly midway between the bright stars Regulus and Pollux, on spring evenings.
- Find the Beehive Cluster first — it shows as a hazy patch under dark skies.
- Regulus in Leo and Pollux in Gemini bracket the constellation.
- Best on spring evenings from the northern hemisphere.
Key facts
- Abbreviation
- Cnc
- Genitive
- Cancri
- Meaning
- The Crab
- Brightest star
- Al Tarf
- Main stars
- 5
- Area rank
- 31st
- Best visible
- March
- Declination
- +20°
- Meteor showers
- Delta Cancrids
- Neighbours
- Gemini, Lynx, Leo Minor, Leo, Hydra, Canis Minor
Deep-sky objects
The Beehive Cluster (M44) is one of the nearest open clusters to Earth, about 600 light-years away, and contains over 1,000 stars. M67, another open cluster in Cancer, is one of the oldest known clusters at roughly 4 billion years.
Frequently asked questions
What does the constellation Cancer look like?
Cancer is a zodiac constellation known as the Crab, its faint stars surrounding the bright Beehive Cluster, visible to the naked eye as a hazy patch.
What is the brightest star in Cancer?
The brightest star in Cancer is Al Tarf, shining at around magnitude 3.53.
When is Cancer best visible?
Cancer is best seen from both hemispheres during March.
What is the story behind Cancer?
In Greek myth, Cancer is the crab that Hera sent to distract Heracles during his battle with the Hydra, and which he crushed underfoot.
Which constellations are near Cancer?
Cancer borders Gemini, Lynx, Leo Minor, Leo, Hydra and Canis Minor.
Gemini
Leo