Cancer Constellation
Cancer (The Crab)
Cancer is one of the 13 ecliptic constellations and represents a crab in Greek mythology. Though it is relatively faint and lacks bright stars, Cancer is rich in history and mythological significance. It is best known for the famous Beehive Cluster located within its boundaries.
Key Features
- Bright Stars: Cancer does not have exceptionally bright stars, but it includes:
- Beta Cancri (Tarf): The brightest star in Cancer, an orange giant located approximately 290 light-years away.
- Delta Cancri (Asellus Australis): A yellow giant star marking part of the crab’s body, also notable for its proximity to the Beehive Cluster.
- Gamma Cancri (Asellus Borealis): A white star representing the northern part of the crab’s body.
- Deep-Sky Objects: Cancer is home to one of the most famous star clusters:
- Beehive Cluster (Messier M44): A bright open star cluster visible to the naked eye, often described as a "swarm of bees."
- Messier 67 (M67): An older and more compact open cluster, containing thousands of stars and considered one of the most studied star clusters.
Mythological Background
In Greek mythology, Cancer is associated with the crab sent by Hera to distract Heracles during his battle with the Hydra. Despite being crushed by Heracles, the crab was honored by Hera and placed among the stars. Cancer’s story reflects themes of perseverance and loyalty, even in the face of overwhelming odds.
The crab also appears in Babylonian mythology, where it was linked to the Moon and water, symbolizing life, fertility, and renewal.
Cultural Significance
Cancer has been historically significant in marking the summer solstice in ancient times. The Tropic of Cancer, a line of latitude, derives its name from the constellation because the Sun once appeared in Cancer during the solstice. Although precession has shifted this alignment, the name persists as a reminder of Cancer’s role in early astronomy.
Cancer Rise and Set Timetable
Time | Elevation | |
Moon Set | 12:27 | -24° |
Astrosession begin | 18:15 | -15° |
Cancer Rise | 19:48 | |
Moon Rise, 57% illuminated | 23:50 | 46° |
Cancer Transit | 02:46 | 67° |
Astrosession end | 06:46 | 34° |
Civil sunrise | 07:20 | 27° |
Sunrise | 07:52 | 21° |
Cancer Set | 09:45 |
Track Cancer Position Throughout the Night
← Sat, 21 December 2024 →
Time | |
Altitude | |
Azimuth |
Annual motion of Cancer
Date | Sun, 22 December 2024 |
Twighlight start | 18:44 |
Twighlight end | 06:07 |
Twighlight duration | 11h 23m |
Rise | 19:48 |
Set | 09:45 |
Elevation at transit | 67° |
Transit time | 02:46 |
Equatorial coordinate | RA: 08h 20m 10s", Dec: 17° 02' 10s |
Magnitude | - |
Constellation |
The graph is structured with the vertical axis showing the hours of the day, ranging from 12 AM to 12 AM the next day, while the horizontal axis spans each day of the year.
The reddish shaded area indicates the periods when the Cancer is above the horizon, visible to observers. The white line marks the times when the celestial object reaches its highest point in the sky each day, known as the transit.
Acknowledgements
We gratefully acknowledge the International Astronomical Union (IAU) for defining and standardizing the official constellation boundaries, which provide a consistent framework for celestial mapping.
Special thanks to Sky & Telescope Magazine and contributors Roger Sinnott and Rick Fienberg for their collaboration in producing the charts and tables. The constellation patterns, drawn by Alan MacRobert, were influenced by the work of H. A. Rey and thoughtfully adjusted to align with earlier traditions.