Cancer Constellation: Stars, Mythology, Deep Space Objects, Star Map & Facts
By : John Whitworth / Updated : Jul 16th, 2026 23:49
Contents
Contents
Cancer Constellation Facts and Figures
Cancer's Stars
Here are a few facts about the stars in the constellation.
- Cancer has six stars that make up the constellation's shape.
- The Hipparcos satellite scanned and detailed one thousand one hundred and eighty-six stars.
- You can see one hundred and thirteen stars within the Cancer constellation borders with the naked eye on a clear night sky.
The Cancer constellation is one of 88 constellations that can be found in the night sky. Cancer is a Latin word; the English meaning/translation is the crab. Cancer's pronunciation is Can-sir.
The genitive form is Cancri, which means any object with Cancri at the end of its name infers a relationship to the constellation. Typically, the thing is within the constellation's boundaries or was once, until the borders were redrawn. Cancer can be shortened or abbreviated to Cnc.
Cancer (Constellation) takes up 505.872 Sq. Degrees of the night sky, equating to 1.23% of the night sky. Cancer is the 31st Largest constellation in the night sky. Thirty Extrasolar Planets in the Cancer constellation are detailed on this site. There is a dedicated page for exoplanets in Cancer.
Charles Messier catalogued two deep-space object(s) within the Cancer's boundary.
Cancer's Stars
Here are a few facts about the stars in the constellation.
- Cancer has Six Stars that make up the constellation's shape.
- The Hipparcos satellite scanned and detailed one thousand one hundred and eighty-six stars.
- You can see one hundred and thirteen stars within the Cancer constellation borders with the naked eye on a clear night sky.
Altarf
Cancer's brightest star is Altarf, about 303.41 light-years from the Sun. The star is designated as Beta Cancri rather than Alpha Cancri. Alpha stars tend to be the brightest in the constellation.
Altarf has an Apparent Magnitude of 3.53 but an Absolute Magnitude of -1.31. The difference between the magnitudes is that the absolute magnitude is the object's brightness as seen from 10 parsecs (32.6 light-years) away. In contrast, the apparent magnitude is the object's brightness as seen from Earth.
Copernicus
Up until mid-2010, the star was known as 55 Cancri, but because of its significance, I.A.U. elected to rename it in a competition. Its significance is that Copernicus has a larger-than-usual number of exoplanets in orbit around it. It has five planets in orbit around the star so far known as of April 2018.
Other Major Stars
This is a list of other stars that make up part of the constellation but have not been detailed above. Other visible stars in the constellation can be found on the Cancer Star List page.
| Name | Bayer | Spectral Type | Distance | Exoplanets |
| Acubens | Alpha Cancri | A5m | 188.32 | |
| Al Tarf | Beta Cancri | K4III | 303.41 | Yes |
| Asellus Borealis | Gamma Cancri | A1IV | 181.20 | |
| Asellus Australis | Delta Cancri | K0III | 130.57 | |
| Decapoda | Iota Cancri A | G8Iab: | 331.13 | |
| Iota Cancri B | Iota Cancri B | G8II... | 279.01 |
Interesting Fun Facts about Cancer Constellation
- Cancer is the Faintest Constellation of all the 12/13 Zodiac star signs.
- The brightest Cancer star is Altarf, sometimes spelt Al Tarf.
How to Find Cancer in the night sky
Northern Hemisphere
The constellation is best viewed from the Beginning Of The Year in the eastern hemisphere before disappearing by July in the northwest.
Southern Hemisphere
The best time to see this is in February when it appears in the northern direction.
Mythology
Cancer was a crab in Ancient Greek Mythology that Hera sent to make things harder for Hercules. It had little effect on the warrior as Hercules fought Hydra for the second labour. Hercules was the Illegitimate son of Zeus and a mortal. Hera, Zeus's wife, is determined to exact revenge on her unfaithful husband.
Cancer Disease
The only connection between Cancer the constellation and Cancer the Disease is that they share the same name. You're not at a higher risk of getting the disease if you are born under the constellation of Cancer. Getting Cancer is down to other factors, including but not limited to genes, lifestyle, including smoking, eating and drinking.
If you are worried, talk to a doctor, as I'm no medical professional. The disease is so called because, in Ancient Greece, Hippocrates and Galen noted, among other things, that the veins around a tumour resemble those of a Crab. StackExchange
Zodiac
Cancer is a member of the Zodiac group of 12 constellations. Astrologers use the Zodiac constellations to predict someone's future based on their date of birth and which constellation appeared after Sunset.
The Zodiac astrological year was divided equally between the twelve signs. Still, when they appear in the night sky, they no longer conform to the Zodiac calendar. The Zodiac constellations are the Thirteen Signs along the Ecliptic, although only twelve are used in astrology.
Cancer Distance From Earth
You cannot just go to one location and arrive in the Cancer constellation, and this is because it is made up of stars at different positions and distances.
The Nearest Main Star (Asellus Australis) in the constellation is at a distance of 130.57 light-years, and the furthest main star is Decapoda, at a distance of 331.13 Light-Years. The average distance to the major stars is 235.61 light-years. Main stars refer to the stars that make up the constellation outline.
Because of the distances of objects, we see how they looked in the past. To know how far back we are looking, take the number and remove the word "Light"; you will get an idea of how long ago they looked like that. By now, the object may look different.
Zodiac
Cancer is a member of the Zodiac group of 12 constellations. Astrologers use the Zodiac constellations to predict someone's future based on their date of birth and which constellation appeared after Sunset.
The Zodiac astrological year was divided equally between the twelve signs, but when they appear in the night sky, they no longer conform to the Zodiac calendar. The Zodiac constellations are the thirteen signs along the Ecliptic, although only twelve are used in astrology.
Cancer Distance From Earth
You cannot just go to one location and arrive in the Cancer constellation, and this is because it is made up of stars at different positions and distances. Of the main stars, the nearest star (Asellus Australis) in the constellation is at a distance of 130.57 light-years, and the furthest star is Decapoda, at a distance of 331.13 light-years. The average distance to the major stars is 235.61 light years. Main stars refer to the stars that make up the constellation outline.
Because of the distances of objects, we see how they looked in the past. To know how far back we are looking, take the amount and remove the word "Light", and you will get an idea of how long ago they looked like that. By now, the object may look different.
Cancer Star Map
Cancer Constellation Facts
| Name | Cancer |
| Abbreviation | Cnc |
| Zodiac Sign | Yes |
| Area | 505.872 sq. deg. |
| Night Sky | 1.23% |
| Size Position | 31st |
| Celestial Hemisphere | North |
| Meteor Shower(s) | 17 |
| Nearest Star | CU Cancri |
| ...with Exoplanet(s) | Copernicus |
| Brightest Star | Altarf |
| Dimmest Star | 5 Cancri |
| Furthest Star | HIP 44539 |
| Bright Star Count | 113 |
| Hipp. Star Count | 1186 |
| Main Star Count | 6 |
| Messier D.S.O. Count | 2 |
| Lists | Deep Space Objects |
| Exoplanets | |
| Meteor Showers | |
| Stars | |
| Main Stars | Acubens |
| Al Tarf | |
| Asellus Borealis | |
| Asellus Australis | |
| Decapoda | |
| Iota Cancri B |
