Cancer Constellation: The Ultimate Guide

In ancient Egypt, the constellation of Cancer was depicted with the beetle as the Egyptians saw it as something similar to their Sun God, "Ra."

The way the beetle rolls its ball of manure across the sand is very similar to how a celestial sphere moves across the night sky.

The ancient Greeks related Cancer to a crab and not to a beetle, which appears in the famous story of the twelve works of Hercules.

When Hercules fought the serpent Hydra, the goddess Hera sent a giant crab to help Hydra finish Hercules.

However, Hercules would win the fight, then, as an act of reward, Hera placed in the sky the figures of Hydra and the Crab in the form of constellations.

In 1563 Tycho Brahe observed planetary conjunction between Jupiter and Saturn in the region of the Cancer constellation.

Thanks to this observation, he discovered the inaccuracy of the ephemeris existing until then.

He would then make a series of observations with which he would adjust the dates of the calendars throughout Europe.

Cancer remains part of the first 88 constellations described by Ptolemy as zodiacal constellations.

Recent research shows that in the regions of the Cancer constellation, there are several stars with planetary systems that are of great importance for studying the solar system's evolution.

Cancer resides in the second quadrant of the Northern Hemisphere (NQ2) at latitudes between 57° S and 90° N, which means we can see the constellation in the night sky from almost all parts of the world.

The only exceptions are the regions closest to the south pole and Antarctica.

Cancer is visible in North America, South America, Europe, Asia, Africa, and Australia.

Cancer is a seasonal constellation, which means it is not seen in the sky year-round. It belongs to the group of northern spring constellations.

We can see it in the Earth's northern hemisphere from the beginning of spring. The best month to observe this constellation is in March.

During July and August, the Sun passes in its region, so it is not visible during those months. It is seen again from September before the sunsets.

Cancer is the faintest constellation of all the zodiac constellations, so it is difficult to find. For this, a very dark sky free of light pollution is recommended.

It is easier first to discover something nearby and find the constellation from there to locate Cancer.

A simple way is to locate the star Regulus of the constellation Leo and the stars Castor and Pollux of Gemini.

Draw an imaginary line connecting Regulus and Castor, then search them for Cancer.

The bordering constellations of Cancer are Canis Minor, Gemini, Hydra, Leo, Leo Minor, and Lynx.

Cancer belongs to 12 zodiacal constellations: Gemini, Taurus, Aries, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricorn, Aquarius, and Pisces.

The brightest stars of Cancer are Altarf, Asellus Australis, Acubens, Asellus Borealis, and Tegmen.

These are the five stars that create the shape of the constellation Cancer. In turn, Cancer officially has 104 stars located within its area.

Of all its stars, 10 of them have proper names designated by the International Astronomical Union (IAU). These are Acubens, Asellus Australis, Asellus Borealis, Copernicus, Gakyid, Meleph, Nahn, Piautos, Tarf, and Tegmine.

Located 290 light-years from the Solar System, Altarf is the brightest star in the Cancer constellation.

It is an orange giant of spectral type K4III, 660 times more luminous than the Sun and about 50 times larger than the Sun.

It is one of the most luminous giants of which there is registration with an apparent magnitude of 3.5.

It has recently been discovered that Tarf has a companion that could be a red dwarf.

Asellus Australis is an orange giant star of spectral type K0III located 136 light-years from the Sun, 11 times larger than the Sun and twice the solar mass.

It has a surface temperature of 4585 K. Its brightness is 53 times higher than that emitted by the Sun.

Historically called Tegmine, meaning "the shell of the crab," Zeta Cancri is a multiple star system located approximately 83.4 light-years from Earth.

The system is composed of at least four stars divided into two binary stars, Zeta-1 Cancri and Zeta-2 Cancri, separated by 5.06 arcseconds.

55 Cancer is a binary star system. It consists of two stars orbiting mutually and is located 41 light-years from our solar system.

Its components are a K-type star (55 Cancri A) and a smaller red dwarf star (55 Cancri B).

Since 2015 it has been known that the system has five extrasolar planets. These are 55 Cancri b (Galileo), 55 Cancri c (Brahe), 55 Cancri d(Lipperhey),55 Cancri e (Janssen), and 55 Cancri f (Harriot).

This planetary system is particularly striking to astronomers. It shows the presence of disks of matter, so it most likely has more planets yet detected.

Because of this, 55 Cancer is one of the most promising stars to host possible extraterrestrial life.

Cancer is also known as the home of several deep-sky objects. Deep-sky objects often mean star clusters, nebulae (interstellar cloud bodies), or galaxies.

Cancer is rich in star clusters and several spiral galaxies in the case of Cancer. The most famous or with better visibility are:

It consists of one of the closest open clusters to the solar system and contains many more stars than most bright clusters close to Earth.

It is located approximately 600 light-years from Earth and is 600 million years old.

Many astronomers propose that both the Persebe cluster and the Hyades cluster have a common or govern since both clusters contain red giants and white dwarfs and a similar distribution and motions.

This open cluster contains at least a thousand stars, of which 100 are sun-like.

Due to its proximity to the Earth, it is one of the most studied star clusters.

NGC 2775 is a spiral galaxy discovered by William Herschel in 1783; what characterizes this galaxy is its enormous distribution of spiral arms that give it the appearance of a ring.

It shows no signs of recent star formation and is part of the Virgo Supercluster, hundreds of galaxies.

It is an open trumpler-type star cluster II,2,r.

It was discovered by Johann Gottfried Koehler around 1779. It is located 2900 light-years from Earth, and its stars are similar in age to the Sun (between 4000-7 billion years).

It contains several variable stars and is also one of the oldest open star clusters known; it is a substantial study body to understand stellar evolution.

NGC 2608 is a barred spiral galaxy with an apparent magnitude of 13.01, has a diameter of 62,000 light-years, and is approximately 93 million light-years away.

It is considered a spiral galaxy of complex design because its spiral arms coil very differently from other galaxies around the central bar.

The shape of this galaxy may be due to gravitational pulls exerted by black holes.

A meteor shower is within the constellation's boundaries called "Delta Candrids."

This occurs from January 1 to 24, and its maximum exposure occurs on January 17 of each year.

• The brightest Cancer star is only 3.5th magnitude; because of this, in the past, the constellation Cancer was often called the "Dark Sign" as it was complicated to see in the night sky.
• Although in modern culture, the constellation of Cancer is depicted with a crab, it was shown with a beetle in the past.
• In the past, the constellation of Cancer was where the Sun passed during the summer solstice. Still, it currently occurs in Taurus because the precession of equinoxes has displaced the Earth.

• Since Cancer is a constellation of the zodiac, it belongs to the zodiac family's constellations.
• Cancer means "Crab," derived from Greek mythology in which the goddess Hera sent a vast crab to fight Hercules, but in the end, the Crab was defeated.
• Cancer is a northern constellation, but we can see it from all the southern hemisphere countries. The best time to observe Cancer is in March.
• Cancer is challenging to locate because its main stars are not bright enough. The best way to find it is with the help of the neighboring constellations, Gemini and Leo.
• The brightest star in the constellation is Tarf (Beta Cancri), 3.5.
• The most notable galaxy within the frontiers of Cancer is NGC 2608(Arp 12), which is characterized by irregular or exotic spiral arms.
• The strongest meteor shower in Cancer is the "Delta Candrids."

1. https://earthsky.org/constellations/cancer-heres-your-constellation/
2. http://www.seasky.org/constellations/constellation-cancer.html
3. https://www.planetguide.net/cancer-constellation/
4. https://www.constellation-guide.com/constellation-list/cancer-constellation/