Early in the spring, the northern hemisphere can see Cancer, the crab constellation. At latitudes between 90 and -60 degrees, it can be seen. It occupies 506 square degrees of the sky and is a medium-sized constellation. Out of the 88 constellations in the night sky, it is the 31st largest. Gemini to the west, Lynx to the north, Leo to the east, Hydra to the south, and Canis Minor to the southwest are its neighbors. It is one of the zodiac’s thirteen constellations. This indicates that it is situated along the Sun’s yearly course through the sky.
The Greek astronomer Ptolemy first identified 48 constellations in the second century, and Cancer was one of them. Latin for “the crab” is its name. In the tale of Hercules’ twelve labors, it is thought to stand in for the crab. To divert Hercules from his battle with the Hydra, the goddess Hera sent it. Hercules kicks the crab so forcefully that it is launched into the night sky amid the stars when it tries to kill him. The crab attempted to snag Hercules’ toe in a different rendition, but Hercules trampled it under his foot. This constellation was regarded by certain ancient societies as the portal via which souls arrived on Earth and were born into human bodies.
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Beehive Cluster (Praesepe, Messier 44, M44, NGC 2632)
Located 577 light years from Earth, the Beehive Cluster is an open star cluster. One of the most crowded and nearby open clusters to the solar system is this one. It is thought to be 600 million years old and has an apparent magnitude of 3.7. The Praesepe name for the Beehive Cluster means “Latin for the manger.
The cluster can be seen with the naked eye. Ptolemy, a Greek astronomer, noticed it and gave it the name “the hazy tumor in Cancer’s breast. The cluster was discovered by Charles Messier in 1769 after being first observed through a telescope by Galileo in 1609.
At least a thousand stars can be found in Praesepe. A third (33%) of them are Sun-like stars, which are categorized as F, G, and K-class stars. More than half of them (63%) are red dwarfs. Blue-white stars with magnitudes between 6 and 6.5 make up the cluster’s brightest stars.
How were the names of the constellations in the zodiac chosen?
How do constellations get their names? The majority of constellation names that we are familiar with come from prehistoric Middle Eastern, Greek, and Roman cultures. They recognized star clusters as the gods, goddesses, creatures, and settings of their myths.
What are the five main stars in the constellation of Cancer called?
Al Tarif, Acubens, Asellus Australis, Asellus Borealis, and Iota Cancri are some of the prominent stars in the constellation of Cancer. The stars Asellus Australis and Borealis are also known as the “northern donkey” and “southern donkey,” respectively.
Ptolemy’s method for finding cancer
Astronomers are most familiar with Cancer as the location of Praesepe (Messier 44), an open cluster commonly known as the Beehive Cluster, which is situated directly in the middle of the constellation. It is one of the closest open clusters to our Solar System, standing about 590 light-years from Earth. The brightest stars in M 44, which has roughly 50 stars overall, are sixth magnitude stars. At magnitude 6.3, Epsilon Cancri is the member that is the brightest. A 1.5 square degree object, or three times the size of the full Moon, Praesepe is also one of the more substantial open clusters that may be seen. When Cancer is high in the sky, it is easiest to see. This period runs from February through May north of the equator. The Beehive Cluster was referred to by Ptolemy as “the hazy mass in the breast of Cancer.” Galileo noticed 40 stars in the cluster, making it one of the first things he saw through his telescope in 1609. Currently, there are roughly 1010 high-probability members, with red dwarfs making up the majority (68%) of them. The two nearby stars, Assellus Borealis and Assellus Australis, were interpreted by the Greeks and Romans as a manger from which two donkeys were eating. In the battle with the Titans, the god Dionysus and his teacher Silenus rode donkeys, which are represented by the stars. The object was described by the ancient Chinese as a “cloud of pollen blown from under willow catkins,” but they actually saw it as a ghost or demon traveling in a carriage.
Also found in Cancer, 2600 light-years from Earth, is the smaller, denser open cluster Messier 67. It is roughly the size of the full Moon and covers a region of 0.5 square degrees. There are about 200 stars in it, the brightest of which are tenth magnitude.
In a September 2002 VLBI experiment, Edward Fomalont and Sergei Kopeikin used the quasar QSO J0842+1835 to determine the speed of gravity.
OJ 287 is a BL Lacertae object that is 3.5 billion light years away that has produced optical outbursts that have been quasi-periodic for around 120 years. These outbursts were originally captured on photographic plates in 1891.
The Ohio Sky Survey was used to make the initial radio detection of it. With a mass of 18 billion solar masses, which is more than six times that calculated for the previous greatest object, it has one of the largest known supermassive black holes in its center.
Why is the crab in the Cancer symbol?
According to astrology, Cancer is the fourth sign of the zodiac and is thought to rule the time between around June 22 and approximately July 22. The Greek mythological crab that bit Heracles while he was battling the Lernaean hydra is related to the creature’s portrayal as a crab (or lobster, or crayfish). Hera, Heracles’ adversary, compensated the crab for being crushed by Heracles by elevating it to the sky.
What fabled being is Cancer?
The most well-known appearance of Cancer, the enormous crab, is in the conflict between Heracles and the Hydra. Cancer was sent to aid the Hydra monster by Hera, who despised Heracles. Unfortunately, things did not turn out the way Cancer had hoped. Heracles swiftly redirected his attention to the crab and defeated it, despite the fact that it was able to cling onto his foot and divert him from the battle with the Hydra. This narrative demonstrates Cancer’s grit and fortitude despite its ultimately fruitless endeavors.
Why are Greek gods chosen as constellation names?
Ancient Greeks referred to constellations as “placings of the stars” that the gods had made. The Greeks thought the Olympians placed those beings, creatures, and things in the heavens for a reason: to serve as clear examples of appropriate conduct. Frequently, complete tales may be followed from one constellation to the next as they unfold over the sky.
As part of his labors, the great hero Heracles vanquished many beasts, including Leo the Nemean Lion, Cancer the Crab, and Taurus the Cretan Bull. This is represented by a large portion of the zodiac (a term derived from the Greek zodiakos kuklos, or “circle of little animals”). The punishments that await mortals who refuse to pay reverence to the gods are depicted in other stories that are even bloodier and more brutal, warning humanity.
When were the names of the constellations given?
Like the names of stars, constellation names come from various sources and each one has a unique origin and meaning. While most constellations produced more recently were named after scientific instruments and exotic creatures, the names of ancient constellations were largely derived from Greek and Roman mythology. The meanings of the 88 constellation names are listed below.
The names of the constellations in the zodiac, as well as other names for constellations, are most commonly associated with Greek mythology. The Greek astronomer Claudius Ptolemy originally compiled a list of these constellations in the second century CE. These constellations were merely listed in Ptolemy’s Almagest without any names. Long before his time, observers were familiar with the constellations.
They consist of:
- Orion (the Hunter) (the Hunter)
- The Andromeda galaxy (the Chained Maiden)
- A Cassiopeia (the Queen)
- Major Ursa (the Great Bear)
- Minor Ursa (the Small Bear)
- Major Canis (the Greater Dog)
- Minor Canis (the Smaller Dog)
- The constellation Auriga (the Charioteer)
- Draco (the Dragon)
- A cygnus (the Swan)
- Water Bearer (the Water Bearer)
Numerous major constellations have names that are connected to mythological characters. These include the majority of the constellations in the Perseus family (Perseus, Andromeda, Cassiopeia, Cetus, Cepheus, Pegasus, and Auriga), the Hercules family (Hercules, Sagitta, Aquila, Lyra, Cygnus, Hydra, Crater, Corvus, Ophiuchus, Serpens, Centaurus, Lupus, Corona Australis, and Ara (Ursa Major, Ursa Minor, Draco, Canes Venatici, Botes, and Corona Borealis).
The majority of the contemporary constellations that Ptolemy did not list were developed between the sixteenth and nineteenth centuries. Due to their location in the far southern sky and invisibility from mid-northern latitudes, many of them were unknown to the Greeks.
Dutch explorers who sailed to Indonesia in 1595 produced twelve constellations. They bore the names of the creatures the explorers met along the way. The Dutch-Flemish astronomer Petrus Plancius initially drew these constellations in 15971598 on a celestial globe. They consist of:
- Apus (the Bird of Paradise)
- A Dorado (the Dolphinfish or Swordfish)
- A Tucana (the Toucan)
- a Volans (the Flying Fish)
In the 17th century, 10 new constellations were added by the Polish astronomer Johannes Hevelius. There are still seven of these in use:
- Venatici Canes (the Hunting Dogs)
- The Lacerta (the Lizard)
- Minor, Leo (the Smaller Lion)
- A scutum (the Shield)
- A sextan (the Sextant)
- A vulpecula (the Little Fox)
Cancer resides in which nebula?
Abell 31 is a planetary nebula that is almost ten light-years wide and nearly 2,000 light-years away from Earth in the constellation of Cancer. It is also known as Sh2-290. Abell 31 is not extremely brilliant, despite being one of the largest planetary nebulae in the sky.
Planetary nebulae are unrelated to planets despite their name. Because some circular planetary nebulae resembled the planets Uranus and Neptune when viewed through small optical telescopes, the term “planetary nebula” first used in the 18th century.
A star with a mass up to eight times that of the Sun is represented by planetary nebulae as it enters its brief final phase of existence. The dying star releases a significant amount of its outer envelope as it burns through the rest of the fuel in its core. After collapsing from a red giant to a white dwarf, this material is heated by the radiation from the stellar remnant and radiates, creating incandescent clouds of gas that can exhibit intricate shapes since the mass being ejected from the star is uneven in time and direction.
The white dwarf will cool and ultimately disappear for billions of years once the nebula has gradually spread throughout space. Similar fate is predicted for our own Sun, but happily it won’t happen for another 5 billion years.
Due to Abell 31’s extreme age, its gas has already begun to spread out into space.
Its main star, a tiny white dwarf that is about 4 times the size of Earth or 0.04 times the size of the Sun, is extremely hot at 85,000 degrees Celsius (150,000F). It has roughly half the mass of the Sun, indicating that it was once a star that was nearly twice as massive as our Sun. As it became older, its stellar winds swept away the star’s outer envelope, and it lost the remaining mass. The star probably started dying approximately 130,000 years ago, after a billion or more years of normal life, based on how quickly those winds are sweeping outward.
The nebula is traveling through space at a brisk rate. The cloud’s southern region is in the direction of motion. This southern region is clearly delineated by a broad bow shock, where the interaction with the surrounding interstellar medium has compressed the nebular gas and dust. The northern limit of the nebula is somewhat hazy because gas travelling in the other direction is moving downhill and is mostly unaffected.
Keep in mind that this image depicts both the red and blue parts of the nebula. Hydrogen is the red gas, and oxygen is the blue gas. The progenitor star is not far from the blue region. Although the oxygen is likely present across the entire nebula, it is only at the center where it is in close enough proximity to the star for it to be illuminated and glow.
The 0.8 meter Schulman Telescope at Arizona’s Mount Lemmon was used to capture this image in December and January of 20112012.