Cassiopeia Constellation Facts

Constellations are groups of stars that have been identified as part of a pattern by ancient civilizations. Our ancestors looked at the shining dots that are stars in the sky and connected those dots together to identify anthropomorphic or animal like forms which became a part of their mythology. Today, more than the mythical value of those constellations, they are useful to modern astronomy as ways of identifying different regions in the sky.

What countries are to Earth maps, constellations are to the sky maps today. Just like a geographer must know his maps well, an astronomer must know and be able to identify the constellations in the sky. Identifying constellations makes it easy for astronomers to identify any object in the nighttime sky.

Location & Sighting

The Cassiopeia constellation is normally visible in the Northern sky and easily identified by its 'W' shape. Part of the Perseus constellation family, this constellation is visible almost throughout the year to people in the northern hemisphere. However, it is most clearly observed in the November sky. This constellation identifies a region in the sky that is very rich in stars. The region is abundant with emission nebulae, many star clusters and even a supernova remnant. The image accompanying this article is that of 'Bubble Nebula' which lies in this constellation.

This constellation was identified long ago in 2nd century AD by the Greek astronomer Claudius Ptolemaeus, also known as Ptolemy. Identifying this constellation makes it easy to identify many surrounding constellations. It is surrounded by the Andromeda constellation on the south, Cepheus constellation in the North, Perseus constellation on the south east and is opposite to the Big Dipper constellation. It is also bordered by Camelopardalis and Lacerta constellations.

It is visible between Earth latitudes of +90° and -20°. Best viewing time in North America is around 9 pm in the month of November. An interesting fact about Cassiopeia is that if it is observed from Alpha Centauri (Second closest binary star system to the Sun), then our Sun would appear to be a part of it and the W shape would be seen as a zigzag pattern.

Myths

The constellation was named after a vain Queen whose story is part of Ancient Greek mythology. Cassiopeia was a queen whose boastfulness about her and her daughter's beauty and narcissism invited the wrath of the Greek Sea God Poseidon. She was supposedly set in the stars as punishment by the Gods. Most of the characters in Cassiopeia's story including her daughter Andromeda have their names given to constellations. The constellation is denoted in old star charts by a queen sitting on the throne.

Interesting Facts

In modern astronomy, a constellation is not just limited to the stars that it is made of, but also the region of sky engulfing it. The International Astronomical Union has divided the sky into regions identified by 88 constellations. The coordinates of this constellation are R.A. 1 h / Dec. +60^o and it falls in the NQ1 quadrant. It covers a total of 598 square degrees of the nighttime sky. Here are some interesting facts.

Brightest Stars in Cassiopeia
There are five prominent stars that make the constellation. The brightest star is an orange giant, Alpha Cassiopeiae (α Cas) with a brightness magnitude of 2.25 and is also known as Shedar, Shadar or Shedir. The nearest star within the constellation is Achird (η Cas) which is a binary system located at a distance of about 19.42 light years away from our Sun. Two of the most luminous stars in the entire galaxy lie in this constellation region. One is Rho Cassiopeiae (ρ Cas) which is a yellow hypergiant star located about 11,650 light years away from Earth. The other one is V509 Cassiopeiae (V509 Cas) located at a position which is 7800 light years away from the Sun.

Supernova Remnants & Deep Space Objects
This region is home to a prominent supernova remnant that is one of the brightest astronomical radio sources. It is known as Cassiopeia A (R.A. 23h 23m 26s / Dec +58° 48′) and the supernova explosion that created it must have been the last such explosion in the Milky way that could have been seen by people on earth about 300 years ago. Another Supernova remnant visible in the constellation is SN 1572 (a.k.a. Tycho's Supernova) that exploded in November 1572.

An interesting deep space object visible in the constellation is an irregular galaxy cataloged as IC 10. It was first discovered by the American astronomer Lewis Swift in 1887. Two prominent open clusters visible in this constellation are M52 and M103. Both these are old and distant star clusters situated far away from Earth.

The next time you observe it in the sky, you will feel like you know this constellation better. There are of course 87 more constellations to explore through your telescope, each holding many surprises and secrets to be revealed.