Throughout time, various civilizations and cultures have looked up into the night sky to see the constellations. Many carry the names of their gods and goddesses, while others were named after stories and adventures. As humans, we are wired to look at objects and see faces, designs, and patterns, and our ancient ancestors took the opportunity to name the constellations after what they saw or thought they were observing.
Stars in the night sky in a constellation are grouped together to form a constellation. Although they look like they are close together when we view them from Earth, they are really very far apart. Each star travels in its own orbit through the Milky Way and the constellation patterns alter over time.
A constellation is a portion of the sky with defined boundaries. All of the stars and any other objects that are located in that boundary are considered to be part of the constellation.
Modern scientific language indicates that stars that form patterns are known as asterisms, and they typically fall within a single constellation and are named for the pattern. This includes nebulae and galaxies. Some may also be part of multiple constellations. Most constellations are seasonal, although there are some that can be seen at certain times of the year.
The sky was divided into 88 specific constellations in 1922 and this is maintain through to today. The 88 constellations include 48 that were listed by the Greek astronomer Ptolemy and 40 new constellations.
Each of the 88 constellations are divided even further as astronomers created star maps that included some of the brightest stars and patterns in the night sky. The maps represent the various positions of the stars as they are seen from Earth. Stars in each constellation may be far apart from each other, but are bright because they are closer to Earth. Other stars are bright because they are large stars.
There isn’t a single point on Earth that we can view all of the constellations. Star maps have been divided into the maps that represent the northern and southern hemispheres. The other factor that can affect what constellations are visible are the seasons when they are viewed.
When we look at the night sky we see in two dimensions and therefore miss the concept of how far away some stars and constellations are because we lack a third dimensional view. People that explore the stars in the sky who aren’t professionals are called skywatchers and in their search for comets, planets, or other celestial events they use a process called “star hopping.”
The word constellation is from the Latin term “constellatio” which loosely translates to “set of stars.”
Just about every civilization reaching back to ancient humans, have looked into the night sky and have seen patterns that formed from the stars. Some cave paintings found in Europe that are over 10,000 years old show images of star formations that are quite similar to the ones that we see now. The earliest records of constellations reach back to around 3,000 years ago when the ancient Babylonians (modern day Iraq) wrote the signs of the zodiac based on the information that was shared by their predecessors.
The records of the Babylonians were shared with the ancient Greeks and in the 4th century BC we see the same zodiacal constellations that were recorded by the Greek astronomer Eudoxos of Cnidus. About 500 years later, Claudius Ptolemy, a Greco-Roman scientist, added the 48 constellations in his book Almagest, and this is the same information that we use today. All 88 constellations are part of the official list by the International Astronomical Union (IAU).
Stars move across our night sky and at certain times of the year there will be different constellations that we see at sunset. The rising constellations rotate based on our Earth and where it is as it travels through space. Constellations are often used to make the seasons in areas where there is very little change between spring and winter.
A majority of the northern sky constellations have Roman and Greek names, but the constellations were monitored, watched and named long before those civilizations. The Babylonians took much of their information about the constellations from the Sumerians that lived 3,000 years before them.
Indications of astronomical observations in India date back to 3300-1300 BCE with the Indus Valley Civilization. The oldest example of their astronomy is the Vedanga Jyotish, a part of the Vedic religious literature that dates 1400-1200 BCE.
The Islamic world had an explosion of enlightenment and developments in science between the 8th and 15th centuries in the areas from Al-Andus region (modern day Portugal and Spain) to Central Asia and India.
The astronomy of Islam influenced European and Byzantine astronomy, and that of West Africa and China. Many of the names used today in relation to the stars reach back to their original Arabic names.
Starting with the end of the 16th century, various countries and cultures began to navigate the seas and use the constellations as a way to guide them. European astronomers made note of the constellations in the South Celestial Pole and used them for seafaring expeditions to Africa, Asia, and the Americas. From there, the modern star catalogs began to be developed.
The International Astronomical Union (IAU) officially defined 88 constellations in 1929. The constellations aren’t drawn in a way that connects the stars, instead, they are kind of rectangular-shaped pieces of the celestial sky with all of the stars inside of them. This created a mutual way for astronomers to be able to talk to each other about the areas of the sky they were studying.
Inside each of the 88 regions are individual groupings that people call constellations. Some of these share the same name as the constellation, however, others don’t. Some of the groupings that people think of as constellations aren’t really official constellations at all.
An example of this is the Big Dipper, which is inside Ursa Major, but the Big Dipper isn’t a constellation, it is an “asterism” or a group of stars that aren’t designated officially, but are well-known by a majority of non-astronomers.
Orion is one of the most recognizable constellations, mainly due to its location. Orion can be viewed from a lot of places throughout the world. It is named after the mythological Greek hunter. The brightest stars in the Orion constellation are Betelgeuse and Rigel.
Ursa Major can be seen in the northern hemisphere. In Latin it means “Larger Bear.” Ursa Major contains the Big Dipper, which is often used as a method to find the direction of north.
Ursa Minor is Latin for “Smaller Bear,” and it’s located near Ursa Major. It also contains what we know as the small ladle or handle of the Little Dipper.
Draco can be seen in the norther hemisphere. In Latin it means “dragon” and it was one of the 48 ancient constellations.
Pegasus is named after the mythological Greek flying horse and can be seen in the northern sky.
Effect on Human Life:
Many are familiar with the zodiac constellations which are the ones that are located in a band that is around 20 degrees wide in the sky. This band is revered because it’s the place where the sun, moon, and planets all move.
There are 13 zodiac constellations. Twelve of these are also used as signs for the zodiac calendar and astrology. Astrology is not to be confused with astronomy. Astrology is the study of the zodiac symbols and stars and the belief that they have influence over human lives. Astronomy is the scientific study of celestial bodies. The 13 zodiac constellations are:
An Alphabetic List of the Constellations:
- Big Dipper
- Canes Venatici
- Canis Major
- Canis Minor
- Coma Berenices
- Corona Australis
- Corona Borealis
- Leo Minor
- Orion’s Belt
- Piscis Austrinus
- Serpens Caput
- Serpens Cauda
- Southern Cross Constellation
- Triangulum Australe
- Ursa Major (“The Big Dipper”)
- Ursa Minor (“The Little Dipper”)
- VY Canis Majoris
Uses for Constellations
Constellations are useful for more than looking beautiful in the sky. If you are familiar with the constellations you can use them and the stars that they contain to help in navigation. If you find Ursa Minor you can find Polaris (the North Star). How high the North Star is in the sky let navigators figure out the latitude for traveling on the oceans.
During ancient times they used the constellations as part of their calendar to tell them when to plant the crops, harvesting time, and when to prepare for the winter.
- The constellation that is the largest is Hydra, which takes up 3.16% of the sky.
- The constellation that is the smallest is Crus, which takes up 0.17% of the sky.
- Asterisms are the small star patterns within a constellation.
- The Big Dipper and the Little Dipper are asterisms.
- There are 22 different constellations that start with the letter “C.”
- There hasn’t been a new constellation or the name of a constellation added in centuries. Today, when an astronomer discovers a new star, it’s simply added to the constellation that it’s closes to.
- Farmers were the first people to make use of constellations to let them know about the seasons changing. This was critical for them so that they knew the time to plant and to harvest crops.
- Historical records during the Mesopotamian culture (4,000 B.C.) referred to the body of stars that we know as constellations.
- The Odyssey, a poem by Homer, spoke of the constellations and 400 years later, Eudoxus of Cnidus wrote about 43 of the constellations.
- The stars are divided into groups that include the 21 Northern Constellations of: Andromeda, Aquila, Auriga, Boötes, Cassiopeia, Cepheus, Corona Borealis, Cygnus, Delphinus, Draco, Equuleus, Hercules, Lyra, Ophiuchus, Pegasus, Perseus, Sagitta, Serpens, Triangulum, Ursa Major and Ursa Minor.
- The 15 Southern Constellations are: Ara, Argo Navis, Canis Major, Canis Minor, Centaurus, Cetus, Corona Australis, Corvus, Crater, Eridanus, Hydra, Lepus, Lupus, Orion and Pisces Austrinus.
- The original constellations were the only ones that were known of until Casper Vopel, a German Globe maker, added two additional constellations in 1536 of Coma Berenices and Antinous.
- It wasn’t until 1589 that the ancient Greeks named any of the constellations with southern stars. At that time, Plancius, a Dutch astronomer started filling in the empty areas in the southern celestial map. He created Trianulus Antarcticus and Crux, and then added more.
- Most of the credit for naming the constellations goes to the Greeks who named them for their mythological heroes and legends. Many of the constellation stories involve mysterious beings and angry gods.
- In the Hindu culture, the Nakshatra is a word used for a lunar mansion. A Nakshatra is one of 27-28 sectors across the ecliptic and they have names that are the most notable star patterns in each of the respective sectors.
- Some of the stars in the constellation look close but are really farther away. They seem close only because they are larger and shine more brightly.