Cancer
The faint crab between two bright beacons
Best on December–February evenings · northern sky.
Cancer is the dimmest of the zodiac constellations, a modest scattering of stars tucked between the brilliant Gemini twins and the bright star Regulus in Leo. What it lacks in brightness it makes up for in position: this patch of sky sits right on the ecliptic, and at its heart lies the Beehive Cluster, one of the finest naked-eye star clusters in the sky.
How to find it
Cancer is best seen on winter evenings from the northern hemisphere. Find the twin bright stars of Gemini — Castor and Pollux — and then look east toward the bright star Regulus in Leo; Cancer occupies the quieter space between them. Once your eyes are dark-adapted, scan that region for the soft glow of the Beehive Cluster near the center of the crab's body.
Brightest stars
Orange Altarf (β Cnc) leads at magnitude 3.52, making it a modestly bright star even by Cancer's humble standards. Asellus Australis (δ Cnc) follows at 3.94, with Acubens (α Cnc) at 4.25 and Asellus Borealis (γ Cnc) at 4.66 — all best appreciated from a dark sky.
Worth seeing
The real prize is the Beehive Cluster (M44), a loose swarm of stars visible to the naked eye as a soft hazy patch on a clear, dark night — one of the closest and most rewarding open clusters in the winter sky.
Frequently asked
When is Cancer visible?
Cancer is best seen on winter evenings, roughly December through February, from the northern hemisphere, when it rides high enough in the south to pick out its faint stars.
What are the brightest stars in Cancer?
Altarf (β Cnc) is the brightest at magnitude 3.52, followed by Asellus Australis at 3.94, Acubens at 4.25, and Asellus Borealis at 4.66 — all fairly faint, so a dark sky helps.
Which hemisphere is Cancer best seen from?
Cancer is a northern-sky constellation and is best seen from the northern hemisphere, though it sits close enough to the celestial equator to be visible from tropical southern latitudes as well.
Nearby constellations
Gemini · Leo · Ursa Major · Auriga · Hydra · Puppis · Orion · Canis Major