Cancer

Cancer is one of the twelve constellations of the zodiac. Its name is Latin for crab and it is commonly represented as one. Its astrological symbol is Cancer.svg (Unicode ). Cancer is a medium-size constellation with an area of 506 square degrees and its stars are rather faint, its brightest star Beta Cancri having an apparent magnitude of 3.5. It contains two stars with known planets, including 55 Cancri, which has five: one super-earth and four gas giants, one of which is in the habitable zone and as such has expected temperatures similar to Earth. Located at the center of the constellation is Praesepe (Messier 44), one of the closest open clusters to Earth and a popular target for amateur astronomers.

Star

Cancer is the dimmest of the zodiacal constellations, having only two stars above the fourth magnitude.[1] The German cartographer Johann Bayer used the Greek letters Alpha through Omega to label the most prominent stars in the constellation, followed by the letter A, then lowercase b, c and d.[4] Within the constellation's borders, there are 104 stars brighter than or equal to apparent magnitude 6.5.

Also known as Altarf, Beta Cancri is the brightest star in Cancer at apparent magnitude 3.5.[7] Located 290 ± 30 light-years from Earth,[8] it is a binary star system, its main component an orange giant of spectral type K4III that is varies slightly from a baseline magnitude of 3.53—dipping by 0.005 magnitude over a period of 6 days.[9] An aging star, it has expanded to around 50 times the Sun's diameter and shines with 660 times its luminosity. It has a faint magnitude 14 red dwarf companion located 29 arcseconds away that takes 76,000 years to complete an orbit.[7] Altarf represents a part of Cancer's body.

At magnitude 3.9 is Delta Cancri, also known as Asellus Australis.[10] Located 131±1 light-years from Earth,[8] it is an orange-hued giant star that has swollen and cooled off the main sequence to become an orange giant with a radius 11 times and luminosity 53 times that of the Sun.[10] Its common name means "southern donkey".[1] The star also holds a record for the longest name, "Arkushanangarushashutu," derived from ancient Babylonian language, which translates to "the southeast star in the Crab." Delta Cancri also makes it easy to find X Cancri, the reddest star in the sky. Known as Asellus Borealis "northern donkey", Gamma Cancri is a white-hued A-type subgiant of spectral type A1IV and magnitude 4.67,[11] that is 35 times as luminous as of the Sun.[12] It is located 181 ± 2 light-years from Earth.[8]

Iota Cancri is a wide double star. The primary is a yellow-hued G-type bright giant star of magnitude 4.0,[13] located 330 ± 20 light-years from Earth.[8] It spent much of its stellar life as a B-type main sequence star before expanding and cooling to its current state as it spent its core hydrogen. The secondary is a white main sequence star of spectral type A3V and magnitude 6.57. Despite having different distances when measured by the HIPPARCOS satellite, the two stars share a common proper motion and appear to be a natural binary system.[13]

Located 181 ± 2 light-years from Earth,[8] Alpha Cancri (Acubens) is a multiple star with a primary component an apparent white main sequence star of spectral type A5 and magnitude 4.26. The secondary is of magnitude 12.0 and is visible in small amateur telescopes. Its common name means "the claw".[1] The primary is actually two very similar white main sequence stars that are 5.3 AU distant from each other and the secondary is two small main sequence stars, most likely red dwarfs, that are 600 AU from the main pair. Hence the system is a quadruple one.[14]

Zeta Cancri or Tegmine ("the shell") is a multiple star system that contains at least four stars located 82 light-years from Earth. The two brightest components are a binary star with an orbital period of 1100 years; the brighter component is a yellow-hued binary pair and the dimmer component is a yellow-hued star of magnitude 6.2. The brighter component is itself a binary star with a period of 59.6 years; its primary is of magnitude 5.6 and its secondary is of magnitude 6.0. This pair is at its greatest separation around 2019.[1]

Ten star systems have been found to have planets. Rho-1 Cancri or 55 Cancri is a binary star approximately 40.9 light-years distant from Earth. 55 Cancri consists of a yellow dwarf and a smaller red dwarf, with five planets orbiting the primary star; one low-mass planet that may be either a hot, water-rich world or a carbon planet and four gas giants. 55 Cancri A, classified as a rare "super metal-rich" star, is one of the top 100 target stars for NASA’s Terrestrial Planet Finder mission, ranked 63rd on the list. The red dwarf 55 Cancri B, a suspected binary, appears to be gravitationally bound to the primary star, as the two share common proper motion.

YBP 1194 is a sunlike star in the open cluster M67 that has been found to have three planets.

Zodiac Sign

Cancer, the fourth sign of the zodiac, is all about home. Those born under this sign are 'roots' kinds of people, and take great pleasure in the comforts of home and family. Cancers are maternal, domestic and love to nurture others. More than likely, their family will be large, too -- the more, the merrier! Cancers will certainly be merry if their home life is serene and harmonious. Traditions are upheld with great zest in a Cancer's household, since these folks prize family history and love communal activities. They also tend to be patriotic, waving the flag whenever possible. A Cancer's good memory is the basis for stories told around the dinner table, and don't be surprised if these folks get emotional about things. Those born under this sign wear their heart on their sleeve, which is just fine by them. The mascot of Cancer is the Crab, and much like this shelled little critter, Cancers are quick to retreat into their shells if it suits their mood. No wonder these folks are called crabby! For Cancer, it's not that big of a deal, though, since they consider this 'shell' a second home (and they do love home). The flip side of this hiding is that shell-bound Crabs are often quite moody. Further, in keeping with their difficulty in sharing their innermost feelings, it can become a Herculean task to pry a Crab out of its secret hiding place. What to do? Give the Crab time -- eventually these folks will come out to play again. When they do, they'll be the first to say so, in keeping with the Cardinal Quality attached to this sign. It's said that Crabs are first to laugh and first to cry, so you can bet they'll fill you in. That shell, by the way, isn't the only tough thing about Crabs. These folks are tenacious and strong-willed and like to get their way. If their well-documented kindness and gentleness doesn't do the trick, however, they're not above using emotional manipulation to make things happen. If that still doesn't work, they'll just go back to their shell and sulk, or find a way to get back at the source of their pain, since Crabs can be rather vindictive. That said, any self-respecting Crab would tell you that they are ultimately motivated by protecting their home and loved ones, a most noble goal. Cancers are ruled by the Moon -- the Great Mother of the heavens in ancient times. Here on Earth, this is manifested in the Crab's maternal instincts and desire to protect home and hearth. This may appear smothering at times, but that's the Crab for you. The Moon is associated with fertility, too, a quality that is most pleasing to Cancers. The Moon is also the ruler of moods, and Cancers have plenty of those. These folks can cry you a river if they're so inclined, and they usually are. They can be overly sensitive, easily hurt and prone to brooding. Even so, Crabs find it easy to be sympathetic to others and are quick to show their affection. Their intuition is also a great help to them, especially in times of stress. The element associated with Cancer is Water. Like the rolling waves of the sea, the Crab's emotions can make quite a splash. These folks tend to pick up on things and bring them in, with the outward result ranging from sentimentality to possessiveness. Crabs need to resist the temptation to become selfish or to feel sorry for themselves, since this behavior won't help. On the bright side, Cancers are good with money (although some consider them too thrifty), probably because they value a sense of security. Crabs are also quick to help others and tend to avoid confrontation. In keeping with their nurturing bent, those born under this sign are a whiz with food. A hearty picnic in the park is heaven-on-earth to most Crabs. Cancers often find that a robust workout session is just the tonic for their touchy feelings. Team sports are always nice, since they offer a sense of community; water polo should be elemental to aquatic Crabs. What are their team colors? The Moon is silver and white. Since Cancers have a tendency to be lazy, however, they may need someone to push them out the door. When it comes to the game of love, eager Crabs are devoted, romantic and able to get things going on their own. Crabs are wise to listen to their gut, since this sign rules the stomach. The great strength of the Cancer-born is the tenacity with which they protect their loved ones. These folks don't ask for much, either: a comfortable home and sense of peace about sums it up. It's that nurturing instinct which makes Cancers a pleasure to be with.

History

The creation of the constellation is explained in Greek mythology by the short-lived association of the crab Karkinos with one of the Twelve Labors of Hercules, in which Hercules battled the multi-headed Lernaean Hydra. Hera had sent Karkinos to distract Hercules and put him at a disadvantage during the battle, but Hercules quickly dispatched the crab by kicking it with such force that it was propelled into the sky. Other accounts had Karkinos grabbing onto Hercules' toe with its claws, but Hercules simply crushed the crab under his foot. Hera, grateful for Karkinos's effort, gave it a place in the sky.[1] Some scholars have suggested that Karkinos was a late addition to the myth of Hercules in order to make the Twelve Labors correspond to the twelve signs of the Zodiac.