Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia
in Greek mythology, who boasted about her unrivalled beauty. Cassiopeia was one of the
48 constellations listed by the 2nd-century Greek astronomer Ptolemy, and it remains one
of the 88 modern constellations today. It is easily recognizable due to its distinctive
'M' shape when in upper culmination but in higher northern locations when near lower
culminations in spring and summer it has a 'W' shape, formed by five bright stars. It
is bordered by Andromeda to the south, Perseus to the southeast, and Cepheus to the north.
It is opposite the Big Dipper. In northern locations above 34ºN latitude it is visible
year-round and in thetropics it can be seen at its clearest in from September to early
November in its characteristic 'M' shape. Even in low southern latitudes below 25ºS
is can be seen low in the North.
Notable features
The four brightest stars of Cassiopeia are all brighter than the third magnitude.
Alpha Cassiopeiae, traditionally called Shedir, is a double star. The primary is an orange-hued
giant of magnitude 2.2, 229 light-years from Earth. The secondary is widely separated from
the primary and is of magnitude 8.9. Its traditional name means "the breast".
Beta Cassiopeiae, or Caph, is a white-hued star of magnitude 2.3, 54 light-years from
Earth. 16th-century Arabian astronomer Al Tizini gave this star the name Al Sanam al
Nakah,, referring to the contemporaneous Persian figure.
The two other notably bright stars in Cassiopeia are both variable stars. Gamma Cassiopeiae
is a shell star, a type of variable star that has a very high rate of rotation. This causes
the star to be somewhat unstable and periodically eject rings of material. Gamma Cassiopeiae
has a minimum magnitude of 3.0 and a maximum magnitude of 1.6; it is currently approximately
magnitude 2.2. Delta Cassiopeiae, also known as "Ruchbah" or "Rukbat," meaning "knee,"
is an Algol-type eclipsing variable star. It varies by 0.1 magnitudes around magnitude
2.7; its period is 2 years and 1 month. Ruchbah appears to have a blue-white hue and it is
99 light-years from Earth. There are several dimmer single stars in Cassiopeia.
Epsilon Cassiopeiae is a blue-white hued star of magnitude 3.3, 442 light-years from Earth.
Rho Cassiopeiae is a semi-regular pulsating variable yellow-hued supergiant star, among
the most luminous stars in the galaxy with a luminosity of approximately 500,000 solar
luminosities. It has a minimum magnitude of 6.2 and a maximum magnitude of 4.1; its period
is approximately 320 days. Rho Cassiopeiae is about 10,000 light-years from Earth.
Cassiopeia possesses several dimmer double stars and binary stars. Eta Cassiopeiae is
a binary star with a period of 480 years. The primary is a yellow-hued star of magnitude
3.5 and the secondary is a red-hued star of magnitude 7.5. The system is 19 light-years
from Earth. Iota Cassiopeiae is a triple star 142 light-years from Earth. The primary is
a white-hued star of magnitude 4.5, the secondary is a yellow-hued star of magnitude 6.9, and
the tertiary is a star of magnitude 8.4. The primary and secondary are close together but
the primary and tertiary are widely separated. Sigma Cassiopeiae is a binary star 1500 light-years
from Earth. It has a green-hued primary of magnitude 5.0 and a blue-hued secondary of
magnitude 7.3. Psi Cassiopeiae is a triple star 193 light-years from Earth. The primary
is an orange-hued giant star of magnitude 4.7 and the secondary is a close pair of stars
that appears to be of magnitude 9.0. Deep-sky objects
Because it lies in rich Milky Way star fields, Cassiopeia contains many deep sky objects,
including open clusters and nebulae. Two Messier objects, M52 and M103, are located
in Cassiopeia; both are open clusters. M52, once described as a "kidney-shaped" cluster,
contains approximately 100 stars and is 5200 light-years from Earth. Its most prominent
member is an orange-hued star of magnitude 8.0 near the cluster's edge. M103 is far poorer
than M52, with only about 25 stars included. It is also more distant, at 8200 light-years
from Earth. Its most prominent member is actually a closer, superimposed double star; it consists
of a 7th-magnitude primary and 10th-magnitude secondary.
The other prominent open clusters in Cassiopeia are NGC 457 and NGC 663, both of which have
about 80 stars. NGC 457 is looser, and its brightest member is Phi Cassiopeiae, a white-hued
supergiant star of magnitude 5.0. The stars of NGC 457, arrayed in chains, are approximately
10,000 light-years from Earth. NGC 663 is both closer, at 8200 light-years from Earth,
and larger, at 0.25 degrees in diameter.
There are two supernova remnants in Cassiopeia. The first, which is unnamed, is the aftermath
of the supernova called Tycho's Star. It was observed in 1572 by Tycho Brahe and now exists
as a bright object in the radio spectrum. Within the 'W' asterism formed by Cassiopeia’s
five major stars lies Cassiopeia A. It is the remnant of a supernova that took place
approximately 300 years ago, and has the distinction of being the strongest radio source observable
outside our solar system. It was perhaps observed as a faint star in 1680 by John Flamsteed.
It was also the subject of the first image returned by the Chandra X-Ray Observatory
in the late 1990s. The shell of matter expelled from the star is moving at 4,000 kilometres
per second; it has a temperature of 30,000 kelvin on average.
NGC 457 is another open cluster in Cassiopeia, also called the E.T. Cluster, the Owl Cluster,
and Caldwell 13. The cluster was discovered in 1787 by William Herschel. It has an overall
magnitude of 6.4 and is approximately 10,000 light-years from Earth, lying in the Perseus
arm of the Milky Way. However, its most prominent member, the double star Phi Cassiopeiae, is
far closer - between 1000 and 4000 light-years away. NGC 457 is fairly rich; it is a Shapley
class e and Trumpler class I 3 r cluster. It is concentrated towards its center and
detached from the star field. It contains more than 100 stars, which vary widely in
brightness. Two members of the Local Group of galaxies
are in Cassiopeia. NGC 185 is a magnitude 9.2 elliptical galaxy of type E0, 2 million
light-years away. Slightly dimmer and more distant NGC 147 is a magnitude 9.3 elliptical
galaxy, like NGC 185 it is an elliptical of type E0; it is 2.3 million light-years from
Earth. Though they do not appear in Andromeda, both dwarf galaxies are gravitationally bound
to the far larger Andromeda Galaxy. Pattern from Alpha Centauri
If one were able to observe Earth's Sun from Alpha Centauri, the closest star to our solar
system, it would appear in Cassiopeia as a yellow-white 0.5 magnitude star. The famous
W of Cassiopeia would become a zig-zag pattern with the Sun at the leftmost end, closest
to ε Cas. Meteor showers
The December Phi Cassiopeiids are a recently discovered early December meteor shower that
radiates from Cassiopeia. Phi Cassiopeiids are very slow, with an entry velocity of approximately
16.7 kilometers per second. The shower's parent body is a Jupiter family comet, though its
specific identity is unknown. Mythology
The constellation is named after Cassiopeia, the queen of Aethiopia. Cassiopeia was the
wife of Cepheus, King of Aethiopia and mother of Princess Andromeda. Cepheus and Cassiopeia
were placed next to each other among the stars, along with Andromeda. She was placed in the
sky as a punishment for her boast that her daughter Andromeda was more beautiful than
the Nereids or, alternatively, that she herself was more beautiful than the sea nymphs. As
punishment, she was forced to wheel around the North Celestial Pole on her throne, spending
half of her time clinging to it so she does not fall off, and Poseidon decreed that Andromeda
should be bound to a rock as prey for the monster Cetus, who was ravishing the Ethiopian
coast. Andromeda was then rescued by the hero Perseus, whom she later married.
Cassiopeia has been variously portrayed throughout her history as a constellation. In Persia,
she was drawn by al-Sufi as a queen holding a staff with a crescent moon in her right
hand, wearing a crown, as well as a two-humped camel. In France, she was portrayed as having
a marble throne and a palm leaf in her left hand, holding her robe in her right hand.
This depiction is from Augustin Royer's 1679 atlas.
In the ancient Celtic world Anu was the mother goddess and considered to be the mother of
all the gods; the Tuatha de Danann. Other references say that she is the mother earth
goddess or the Goddess of fertility. On the Cork Kerry border are two mountains called
the Paps of Anu On the top of each mountain are stone structures or cairns that when viewed
from a distance make the two mountains look like a pair of breasts. Anu was known, in
the Celtic World, by several similar names: Danu or Don being the most popular alternatives.
She was a Mother-Goddess, the wife of the Sun God, Belenos, and considered to be the
ancestor of all the Gods, the Tuatha dé Danann, who found themselves obliged to reside in
the Otherworld when Miled brought the Celts to the British Isles. She still looks down
on us from the night's sky where she appears as Llys Don, better known as the constellation
of Casseopeia. In non-Western astronomy
In Chinese astronomy, the stars forming the constellation Cassiopeia are found among three
areas: the Purple Forbidden enclosure, the Black Tortoise of the North, and the White
Tiger of the West. The Chinese astronomers saw several figures
in what is modern-day Cassiopeia. Kappa, Eta, and Mu Cassopeiae formed a constellation called
the Bridge of the Kings; when seen along with Alpha and Beta Cassiopeiae, they formed the
great chariot Wang-Liang. The charioteer's whip was represented by Gamma Cassiopeiae,
sometimes called "Tsih", the Chinese word for "whip".
In the 1600s, various Biblical figures were depicted in the stars of Cassiopeia. These
included Bathsheba, Solomon's mother; Deborah, an Old Testament prophet; and Mary Magdalene.
a disciple of Jesus. A figure called the "Tinted Hand" also appeared
in the stars of Cassiopeia in some Arab atlases. This is variously said to represent a woman's
hand dyed red with henna, as well as the bloodied hand of Muhammad's daughter Fatima. The hand
is made up of the stars α Cas, β Cas, γ Cas, δ Cas, ε Cas, and η Cas. The arm is
made up of the stars α Per, γ Per, δ Per, ε Per, η Per, and ν Per.
Another Arab constellation that incorporated the stars of Cassiopeia was the Camel. Its
head was composed of Lambda, Kappa, Iota, and Phi Andromedae; its hump was Beta Cassiopeiae;
its body was the rest of Cassiopeia, and the legs were composed of stars in Perseus and
Andromeda. Other cultures see a hand or moose antlers
in the pattern. These include the Lapps, for whom the W of Cassiopeia forms an elk antler.
The Chukchi of Siberia similarly saw the five main stars as five reindeer stags.
The people of the Marshall Islands saw Cassiopeia as part of a great porpoise constellation.
The main stars of Cassiopeia make its tail, Andromeda and Triangulum form its body, and
Aries makes its head. In Hawaii, Alpha, Beta, and Gamma Cassiopeiae were named. Alpha Cassiopeiae
was called Poloahilani, Beta Cassiopeiae was called Polula, and Gamma Cassiopeiae was called
Mulehu. The people of Pukapuka saw the figure of Cassiopeia as a distinct constellation
called Na Taki-tolu-a-Mataliki. In popular culture
In the 1997 film Contact starring Jodie Foster and Matthew McConaughey, Foster's character
Doctor Arroway has the following line of dialogue: "You see that large W-shaped constellation
there? That's Cassiopeia. And Cassiopeia A gives off a whole lot of radio signals. I
listen to them a lot. It's a remnant of a supernova."
In the 1998 episode of The X-Files, "Patient X", guest starring Veronica Cartwright, Cartwright's
character Cassandra Spender, an alien abductee, leaves fingerprints on a window corresponding
to the constellation Cassiopeia, a reference to the character's name as well as an implied
origin for the aliens who abducted her. In the 2001 movie Serendipity, starring John
Cusack and Kate Beckinsale, Cusack tells Beckinsale about the constellation Cassiopeia the night
they meet one another after noticing that the freckles on her forearm match the constellation's
pattern exactly. In Sara Bareilles' 2013 album The Blessed
Unrest, the 7th track is titled "Cassiopeia" and is lyrically and metaphorically about
the stars. During the making of The Blessed Unrest, she was given a book about astronomy.
She found herself fascinated reading about the different constellations, especially Cassiopeia,
as well as the topic of supernovas, the incredibly bright bursts of light that stars give off
when they explode. Inspired, she penned this song imagining Cassiopeia as a human, and
falling in love with another star. "I started to think about how that might feel to personify,
you know? The idea of being a star and so far away from everything around you," she
told Radio.com "What if a star falls in love? The song is this idea that you give something
up to come together." In the movie The Green Mile, while Michael
Clarke Duncan's character John Coffey is being smuggled from prison, Coffey points at the
sky at what appears to be Cassiopeia and says to Paul Edgecomb, "Look boss! It's Cassie,
the lady in the rockin' chair!" In the 2011 episode of The Big Bang Theory,
"The Wiggly Finger Catalyst,", Rajesh "Raj" Koothrappali is out on a date with a deaf
woman named Emily. Raj did not know American Sign Language, so Howard Wolowitz assists
Raj on the date by translating for him. Howard, however, is upset and bored by the end of
the date, so he translates things differently than Raj says them. At one point, as the three
were walking out of the restaurant, Raj points to the night sky and says, "It's a little
hard to see with the city lights, but that W-shaped constellation is Cassiopeia. And
she was the mother of Andromeda, who's over there." Howard, after a moment, translates
it, "Look, pretty stars." In the children's novel Momo, by German author
Michael Ende, the heroine finds a turtle named Cassiopeia.
Cassiopeia is also the name of the fanclub for the Korean boy-band TVXQ. The five stars
that make up the constellation represent the 5 members of the group.
In the Japan's first super sentai series, "Himitsu Sentai Gorenger", Cassiopeia is the
constellation whose cosmic rays weaken the main enemy Black Cross Fuhrer and thus was
incorporated into Gorenger's finisher. Each syllable of Cassiopeia was also spelled out
by the first Japanese letter of each ranger's surname spelling Ka-Shi-O-Pe-A.
Namesakes USS Cassiopeia was a United States Navy Crater-class
cargo ship named after the constellation. See also
IC 10 – dwarf galaxy SN 1572 – Tycho's Star or Tycho's Supernova
- B Cassiopeiae Cepheus XR-1 - radio source actually in Cass.
Cassiopeia References
Krause O; Rieke GH; Birkmann SM; Le Floc'h E; Gordon KD; Egami E; Bieging J; Hughes JP,
Young ET, Hinz JL, Quanz SP, Hines DC. "Infrared echoes near the supernova remnant Cassiopeia
A". Science 308: 1604–6. arXiv:astro-ph/0506186. Bibcode:2005Sci...308.1604K. doi:10.1126/science.1112035.
PMID 15947181. Levy, David H., Deep Sky Objects, Prometheus
Books, ISBN 1-59102-361-0 Ridpath, Ian; Tirion, Wil, Stars and Planets
Guide, Princeton University Press, ISBN 0-691-08913-2 Ian Ridpath; Wil Tirion. Stars and Planets
Guide. London: Collins. ISBN 978-0-00-725120-9. Staal, Julius D. W.. The New Patterns in the
Sky: Myths and Legends of the Stars. The McDonald and Woodward Publishing Company. ISBN 978-0-939923-04-5.
External links The Deep Photographic Guide to the Constellations:
Cassiopeia The clickable Cassiopeia
Star Tales – Cassiopeia Cassiopeia Constellation at Constellation
Guide