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10 Interesting Cancer Constellation Facts, Myths, and FAQs

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Cancer Constellation

There are 12 zodiac signs, and they get their names from the constellations in the sky. One of the least understood is the constellation Cancer. It’s hard to spot, but there are many interesting facts and tidbits about it.

Here are 10 of the most interesting ones, as well as a brief rundown of the interesting mythology surrounding the Cancer constellation!

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The 10 Interesting Cancer Constellation Facts

1. Cancer Is a Giant Crab

Cancer Constellation

Image Credit: Pike-28, Shutterstock

While Cancer is a well-known astrological sign and constellation, not everyone realizes what it actually is. The constellation Cancer looks like a giant crab, although it’s a bit difficult to put all the pieces together with the naked eye.


2. You Can’t See Most of Cancer’s Stars

If you’re looking up at the night sky and trying to connect all the pieces of Cancer, you won’t be able to do it. Most of Cancer’s stars are extremely dim. You’ll either need optimal viewing conditions with no light pollution or binoculars and/or a telescope to spot most of the stars in the Cancer constellation.


3. You Can See Cancer in the Northern Hemisphere in Early Spring

While you can’t see many of Cancer’s stars without a visual aid, if you’re not looking at the right time of the year, you won’t be able to see the stars no matter what you do. The best time to view the Cancer constellation in the northern hemisphere is during early spring, although you can see bits of it throughout the winter.


4. You Can See Cancer in the Southern Hemisphere During Autumn

Cancer Constellation

Image Credit: Pike-28, Shutterstock

The southern hemisphere is about the reverse of the northern hemisphere, so you won’t be able to view the constellation during the winter or early spring, but you’ll get optimal viewing conditions in the fall, and you can spot it throughout the summer.


5. There Are Two Messier Objects in Cancer

Professional and amateur astronomers alike seek out Messier objects, and if you look into the Cancer constellation, there are two there. The first Messier object is the Beehive cluster (M44), which looks like a fuzzy star to the naked eye. But when you take a closer look with binoculars or a telescope, there are over 200 stars in the cluster! The other Messier object is M67. It’s not nearly as bright, but it also contains hundreds of stars that you can see with binoculars or a telescope.


6. Al Tarf Is Cancer’s Brightest Star

The Cancer constellation is hard to see in general, and nothing highlights this quite like the fact that Al Tarf is the constellation’s brightest star, but it only has a magnitude of 3.6. While you can see that under the right conditions just by looking up, it will not be the brightest object in the sky.


7. There Are 10 Named Stars In Cancer

Cancer Constellation

Image Credit: Artsiom P, Shutterstock

While you won’t be able to see most of Cancer’s named stars with the naked eye, astronomers have named 10 of them. Those names (alphabetically) are Acubens, Asellus Australis, Asellus Borealis, Copernicus, Gakyid, Meleph, Nahn, Piautos, Tarf, and Tegmine.


8. Cancer Looks Like an Upside-Down Y

While the Cancer constellation represents a crab in Latin mythology, you shouldn’t look for a generic crab if you’re trying to spot the constellation for yourself. Instead, look for an upside-down Y. These are the brightest and easiest stars to spot in the constellation — and without binoculars or a telescope, they’re the only ones that you’ll spot.


9. 55 Cancri Has At Least Five Exoplanets

While 55 Cancri isn’t an officially named star and you can’t see it without a telescope, it’s spiked a great deal of interest from astronomers. 55 Cancri has at least five exoplanets, which is among the most that astronomers have spotted around distant stars so far.

However, with the James Webb Space Telescope recently coming online, scientists expect to find far more exoplanets. Maybe 55 Cancri has a few more exoplanets for us to marvel at!


10. Two Galaxies Are Interacting With Each Other in Cancer

Cancer Constellation

Image Credit: D W Graves Photography, Shutterstock

If you point the James Webb or Hubble telescope at the Cancer constellation, you’ll pick up far more galaxies than just two. But what makes NGC 2535 and NGC 2536 so interesting is that they’re actively interacting with each other.

These aren’t galaxies that you can view with the naked eye or even binoculars, but with a powerful enough telescope and ideal viewing conditions, you might be able to spot them from Earth’s surface.

telescope divider 1Cancer Constellation Mythology

While the Cancer constellation is a bit challenging to spot in the sky, the Latin mythology behind the constellation is extremely interesting.

The Cancer crab comes from the Hercules saga, being part of the 12 labors that Hercules had to perform as penance for killing his family.

Cancer shows up during the second labor, and the giant crab pinches Hercules’s foot. From there, the stories vary. The first tale says that Hercules crushes the crab with his foot, killing it, and then Hera rewards Cancer by placing the giant crab in the stars.

The second tale states that Hercules kicks Cancer so hard that he flies into the sky. The exact conclusion doesn’t matter too much because either way, legend has it that Cancer is now among the stars after a battle with Hercules.

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Final Thoughts

The Cancer constellation might not be the easiest constellation to view, but it’s certainly one of the most interesting! Now that you know more about it, go ahead and challenge yourself to find it in the night sky.

If you can’t find it on your own, there are plenty of star charts and apps that will help guide you and get you looking in the right direction!


Featured Image Credit: Roman Voloshyn, Shutterstock

About the Author Robert Sparks

Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.

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