First of all, what is a constellation?
Basically, it is a group of Stars. All constellations, including the Ursa Major Constellation, are an area on the celestial sphere (an imaginary sphere) where a group of visible stars are located.
These stars typically form a pattern or outline, which we perceive to represent an inanimate object, (like the Plough or Big Dipper); an animal (like the Great Bear, or Little Bear); a mythical person (like Orion, the mythical hunter, Hera, and Zeus the god who put him in the sky according to Greek mythology) or even a type of creature like Nymphs.
The origins of the earliest Constellations go back to prehistory.
It is also an astronomy term that is oftenused to describe a variety of groups of stars that have been given a specific name such as – Sagittarius, Orion or Leo.
Constellations are constantly moving and move in the direction from East to West.
The Ursa Major Constellation – Facts in brief:
What is it? –
The Constellation Ursa Major is the largest constellation in the Northern Hemisphere and the third largest Constellation overall in the night sky.
The name ‘Ursa Major ’, from the Latin language and means ‘the Great Bear’, or the Larger Bear’, and is sometimes abbreviated to UMa.
The Ursa Major Constellation is quite easy to recognize, as it resembles the outline of a big bear, if you join the dots and use your imagination.
In the 2nd century AD it was one of the 48 earlier Constellations listed by Greek Astronomer Ptolemy.
Where is it located? –
The Ursa Major Constellation is positioned in the second quadrant of the Northern Hemisphere, north of the celestial equator and very close to the North Pole.
It is sometimes referred to as being located in the NQ2 Quadrant.
The 8 neighboring Constellations of Ursa Major are part of the Ursa Major family of Constellations.
This includes
- Bootes, Draco, Camelopardalis, Lynx, Canes Venatici, Leo Minor, Coma Berenices, and Ursa Minor.
Where can it be seen?
Co-ordinates of a right ascension, or left ascension and their declination are used to locate all of the Constellations, like Ursa Major.
The bright Stars of Ursa Major can be more easily observed from the Northern Hemisphere, it lies very close to the North Pole, in the Northern Sky.
It can be seen all year in the Northern Hemisphere, although the best time of year to view it is in the spring, around April time, when it is high above the north eastern horizon.
However, depending on where in the world you are viewing from it may be upside down or lying on its side.
Ursa Majoris found at around 10 hours, 40 minutes right ascension and a 56-degree north declination, in the Northern Celestial Sky.
Visibility from the Northern Hemisphere
The Constellation of Ursa Major is the third largest Constellation in the sky.
It is visible in the Northern Hemisphere at latitudes between +90 degrees and – 30 degrees
Constellation Ursa Major covers an area of 1280 square degrees in the night sky.
In the Southern Hemisphere
The Ursa Major Constellation is partly visible from the northerly areas of the Southern Hemisphere.
How can you identify Ursa Major?
The simplest method for spotting any particular Constellation from Earth is to first of all locate the brightest star in that Constellation, and then look at the neighboring illuminations, to see if you can identify a recognizable pattern.
The Ursa Major Constellation looks like the outline of a large bear.
It can be spotted if you look towards the northerly region of the Northern Hemisphere night sky, between the Constellation of Bootes, Constellation Canes Venatici, Constellation Lynx and the Constellation of Leo Minor
It is represented as the Great Bear in the night sky, and often spotted by locating the Big Dipper asterism (also known as the Plough asterism) part of the Constellation.
This is one of the most recognizable shapes in the sky and is recognized by many ancient cultures from the Greeks to the Romans and is the subject of myths and highly important used as a navigation tool in the sky.
It has even been mentioned as far back as the scripting of the Bible and in the writings of the Greek author, Homer, in the 8th century BC.
In particular the bright stars Dubhe (Alpha Ursae Majoris) and Merak (Beta Ursae Majoris) are used as a pointer for finding the North Star (Polaris), as they point in that direction.
The constellation of Ursa Major is the leading member of the Ursa Major family of Constellations.
The Star System of Ursa Major
Ptolemy catalogued 8 of the constellation’s brightest Stars (Seven Stars of these eight brightest Stars form the Big Dipper asterism).
The Seven Stars of the Big Dipper are:
- Alkaid; Alioth, Dubhe; Megrez; Merak; Mizar and Phecda
The star system of Constellation Ursa Major has:
- A total of 135 Stars
- 18 named fixed Stars approved by the International Astronomical Union (IAU) – Alkaid; Alcor; Mizar; Alioth; Alula Australis; Alula Borealis. El Koprah; Megrez; Phecda; Ta Tsun; Tania Australis; Tania Borealis; Merak; Dubhe; Al Haud; Talitha Australis; Talitha Borealis and Muscida.
- 13 bright Stars with known planets
- The boundary of the constellation of Ursa Major has 21 Stars that contain exoplanets although in total there are 35 Stars that host exoplanets associated with this Constellation. Exoplanets are being discovered all the time, so the number could increase.
The brightest host Star is 4 Uma and has a Star magnitude of 0.15 followed by 47 Uma and G-196-3.
- 7 Messier objects
- One Triple Star system, Zeta Ursae Majoris, with apparent magnitudes of 2.2; 3.9 and 4.0.
FACT:
It is the combined light of the various bright stars in this star system that produces enough light to give Alioth (Epsilon Ursae Majoris) the brightest star status in the Constellation of Ursa Major.
Spotting the Ursa Major Constellation in the night sky
The bright Star, Alioth located on the tip of the triangle joined to the quadrangle, is used to spot the Ursa Major Constellation and its big bear shape.
This simple technique can be used to spot other Constellation patterns too like the Hunter (Orion) or the smaller Constellation Ursa Minor.
The Location of the Constellation of Ursa Major
The Constellation Ursa Major at a glance is located:
- Below Constellation Ursa Minor
- Between Constellations Draco and Constellation Lynx
- Above Constellations Leo Minor, and Canes Venatici
FACT: The ecliptic is an imaginary line tracing the route that The Sun, the Moon, and the Planets take across the sky each year. It usually refers to the route that the Earth takes around the Sun and is the measure that the positions of the Zodiac Constellations are based upon
The Celestial Equator is the projection of the terrestrial equator into space.
The Constellation of Ursa Major is most prominent in the Northern Hemisphere, if looking north at any time of the year (from latitudes of +90 degrees to – 30 degrees).
As the Constellation of Ursa Major is made up of bright Stars in different locations.
It is less visible from the Northern Hemisphere as it is located above the horizon within Northern Celestial Hemisphere.
The best time to spot it is at night in the month of April.
How is it formed and named?
The Constellation of Ursa Major ranks as the 3rd largest Constellation in the Northern Celestial Sky, and it fills an area of 1280 square degrees.
It has a simple and easy to identify shape like ‘a large bear’
It is formed by the positions of its bright Stars that form a robust shape that resembles a great bear:
- The nose of the Great Bear – Muscida
- Main body square – Megrez, Dubhe, Merak and Phecda
- The foot on the front leg – Talitha
- Feet on the back legs – Tanis Borealis, Tania Australis, Alula Borealis and Aulua Australis
- The tail – Alioth, Alcor and Mizar
- Tip of the tail – Alkaid
The International Astronomical Union (IAU), has defined the boundaries of the Constellation of Ursa Major as having several stars that are visible by the naked eye.
The name of the Constellation Ursa Major is often abbreviated simply to ‘UMa’.
The main Stars in Constellation Ursa Major
There are many different types of Stars within Ursa Major.
The named stars of Ursa Major are each categorized by letters of the Greek alphabet. This is its Bayer designation, a stellar designation identifying Stars by their genitive form of the parent constellation’s Latin name.
Fact: the brighter the luminosity of the star the lower the apparent magnitude number.
Normally, bright Stars are listed from the brightest Star, (the alpha star), then in decreasing order of luminosity through the Greek alphabet.
1. Dubhe however, the bright Star that is named the Alpha Star in Ursa Major is actually the second brightest Star, Dubhe (Alpha Ursae Majoris, or Alpha UMa) and is located around 125 light years from the Sun.
It is a Giant Star and one of two bright ‘pointer’ Stars in the UM Constellation that point in the direction of Polaris, the North Star.
2. Alioth (Epsilon Ursae Majoris, e UMa) is the brightest Star in Ursa Major and gets its name from the Latin language.
It is a variable Star that is a Brown Dwarf Star and has an apparent magnitude of 1.77 located 81 million light years from the Sun.
3. Alkaid (Eta Ursae Majoris, H UMa) is the third brightest Star in Ursa Major. It is not part of the moving group of Stars in the Big Dipper asterism. It has a visual magnitude of 1.84 and is located 101 light years from the Sun
4. Mizar (Zeta Ursae Majoris, z UMa) is a second–magnitude Star. It is a binary Star that along with the fainter Star Alcor forms a well-known double Star. It is located around 83 million light years from the Sun with a combined visual magnitude of 2.04.
5. Merak(Beta Ursae Majoris, b UMa) is a bright Star in the northern circumpolar constellation of Ursa Major and It is located around 79.7 light years from the Sun with a visual magnitude of 2.34.
6. Phecda (Gamma Ursae Majoris, y UMa) is a main sequence Star in Ursa Major that is one member of the moving group of visible to the naked eye. It is located around 83.2 light years from the Sun with a visual magnitude of 2.41.
7. Megrez (Delta Ursae Majoris) is a Star in the northern circumpolar constellation of Ursa Major that is visible to the naked eye. It is located around 81 light years from the Sun with a visual magnitude of 3.3.
8. Ta Tsun (Psi Ursae Majoris) is a Star in the northern circumpolar constellation of Ursa Major. It is located around 144.5 light years distant from Earth with a visual magnitude of 3.01.
9. Tania Australis (Mu Ursae Majoris. M UMa) is a binary Star It is located around 230 light years away from the Sun with a visual magnitude of 3.06.
10. Talitha (Iota Ursae Majoris, I UMa) is a Star System in the northern circumpolar constellation of Ursa Major. It is located around 47.3 light years from the Sun with a variable apparent visual magnitude of 3.14.
11. Al Haud, Sarir (Theta Ursae Majoris, O UMa) a suspected spectroscopic binary Star system with an apparent visual magnitude of 3.17, and 44 light years from the Sun.
12. Megrez (Delta Ursae Majoris) a star in the northern circumpolar constellation of Ursa Major, with an apparent visual magnitude of 3.3 and 81 light years from the Sun.
13. Muscida (Omicron Ursae Majoris, O UMa) is a Star System in the northern circumpolar constellation of Ursa Major, with an apparent visual magnitude of 3.35 and located around 179 light years from the Sun. It is a Star with an extrasolar Planet.
14. Tania Borealis (Lambada Ursae Majoris) a star in the northern circumpolar constellation of Ursa Major, with an apparent visual magnitude of 3.45 and around 138 light years from the Sun.
15. Alula Borealis (Nu Ursae Majoris, N UMa) a double star in the northern circumpolar constellation of Ursa Major, with an apparent visual magnitude of 3.49 and around 421 light years from the Sun.
16. Alkaphrah (Kappa Ursae Majoris, K UMa) a binary star in the constellation of Ursa Major, with an apparent visual magnitude of 3.60 and around 358 light years from the Sun.
FACT: the Ursa Major moving groups of stars within Ursa Major, also known as Collinder 285, has 14 member Stars and once believed to have been an open cluster:
How do the Bright Stars of the Ursa Major Constellation shape up?
The Bright Stars
If you look up and into the night sky you can imagine the recognizable Big Bear outline of the Constellation of Ursa Major, by the 7 main bright Stars, which make up the outline of the Big Dipper (The Plough).
Formally named Stars
There are 22 formally named Stars within the Constellation of Ursa Major
Stars with Planets
The Constellation Ursa Major has 13 Stars with known Planets orbiting around them in the solar system but they are unlikely to be able to support life forms.
Ursa Major has a total of 35 Stars with exoplanets (extrasolar planets), but only 21 around its boundary line. The host Stars are:
Other notable Stars and well-known Deep Sky Objects and Galaxies within the Constellation area include:
- The Owl Nebula
- The Pin Wheel Galaxy
- Bode’s Galaxy
- The Cigar Galaxy
- The Spindle Galaxy
- Winnecke 4
- 2 Barred Spiral Galaxies
Not all the stars within the Ursa Major Constellation are visible to the naked eye but with telescopes and modern imagery techniques is it possible to glimpse the stars.
When was it first discovered? –
The ancient Greeks were the first ancient culture to name 88 Constellations in the sky.
The Constellation Ursa Major ranks as the third largest Constellation in the night sky in area and was one of the 88 named by the Greek astronomer Ptolemy.
These Constellations were each given 3-letter abbreviations to help identify them and the Stars within those Constellations are also referred to by those 3-letter codes.
When referring to a Star within a Constellation it is given the genitive form of the Constellation name, ‘Majoris’.
FACT: In Latin, the genitive is the case of description.
Why and what is the purpose of Ursa Major? –
In ancient times the dots, bright lights and perceived objects in the sky were of great interest and the makings of folklore to a great range of people from seamen to farmers.
From children to the elderly, we have had an ongoing fascination, with our solar system and star system. Perhaps it’s because the enormity and variety within it makes us realize just how large and exciting the universe is.
FACT: The Star System or Stellar System is a small number of stars that orbit around each other and are bound together by gravity.
When it becomes a large group of stars, again bound together in the same way, by gravity, it is known as a Galaxy or Star Cluster.
Whether they contain small groups of stars or larger groups of stars they both come under the classification of ‘Star System’.
The Constellations in the night sky were a useful navigation tool and guide as well as the subject of legends and myths, about characters like Zeus, Orion and other powerful gods.
42 of Constellations have been named after animals with a story behind each name.
Constellations change their positions throughout the year as the Earth rotates around the Sun.
This means our position in space is forever changing and as a result our view of what’s in space changes too, and will continue to do so.
Background & Facts:
The neighbors of Constellation Ursa Major
The Constellation of Phoenix is neighbored by several constellations in the Northern Sky: and can be used as the guide point for finding Ursa Major in the sky.
This large Constellation of Ursa Major is bordered by –
- Camelopardalis – to the Northeast
- Draco and Bootes – the Northwest
- Constellations Lynx and Leo Minor –to the East and Southeast
- Constellations Canes Venatici and Como Berenices – to the Southwest
Within Constellation Ursa Major
The Constellation of Ursa Major is formed by of a number of different components
The different components housed by the Constellation Ursa Major are mainly Stars, Deep Sky Objects, Messier Objects and Galaxies.
The different types of Stars
There are many different types of Stars in the star system categorized by size, lifespan and luminosity.
Generally, larger Stars have a shorter lifespan.
Stars are formed from clouds of interstellar gas and include:
Red Dwarf Stars
Most of the stars in the galaxy are Red Dwarf Stars. They are small in size measuring about 40-50% of the mass of The Sun. They are cool and their luminosity has only about 10% of the brightness of the Sun (our brightest Star), and they live for longer.
Brown Dwarf Stars
These are known as failed stars that form like other stars but don’t reach the mass, heat or density to begin the nuclear fusion process. They are only about 8% of the mass of the Sun and are red not brown, and not easy to spot in the night sky.
Red Giant Stars
These are giant luminous stars that have a low or medium mass. A Red Giant Star is formed when a star expands its volume by fusing all of its hydrogen into helium, and then burning the helium to produce carbon and oxygen to expand.
Blue Giants
These are giant, bright stars that range from 10-100 times the size of the Sun and are 1000 times brighter. They are big and hot and therefore burn out quickly. The biggest are called Blue super giants or hyper giants. The biggest ever discovered was about 10 million times brighter than the Sun,
Yellow Dwarfs
These are main-sequence stars like the Sun, but only 80% of its size, and are bright stars,
White Dwarfs
These are small burnt out husks of stars, about the same size as the Earth. White Dwarfs are dense and represent the final state of evolution for a star, like most stars in the galaxy.
Black Dwarfs
These are the remains of a White Dwarf after it cools and darkens. This is likely to happen after about 10 billion years of life.
White Stars
These are also main-sequence stars like the Sun, but twice the size, and are bright stars and hot.
Other types of stars include the Orange Giant, Neutron stars, Variable Stars and Binary Stars
Orange Giant Stars
Other types of stars include Neutron stars, Variable Stars and Binary Stars
Bright Stars
The sky is home to various bright stars.
The brightness of a star is measured by a value called its magnitude and they come in different sizes, composition, mass and color. Their vast distance away from us is measured in light years from either the Earth or the Sun.
The lower the magnitude value the brighter the star appears in the night sky when viewed from Earth.
FACT: The Sun is considered to be the brightest star in the sky.
There are 18 named stars known to host planets within the Constellation Ursa Major that have been officially approved by the International Astronomical Union (IAU)
Deep Sky Objects
FACT: A Deep Sky Object is an astronomical object, that is not a solar system object like the Sun, Moon, Comet or a Planet.
An individual Star is not considered to be a Deep Sky Object.
Deep Sky Objects are faint objects that can still be observed by the naked eye in the night sky from Earth.
They include Galaxies, Star Clusters and Planetary Nebulae.
Objects belonging to the Messier catalogue, the New General Messier catalogue (NGC) and Index Catalogue (IC), within Constellation Ursa Major include:
- Messier 81, Bode’s Galaxy – a Spiral Galaxy with visual magnitude 6.94
- Messier 101 (the Pinwheel Galaxy). An intermediate Spiral Galaxy with visual magnitude 7.86
- Messier 82 (The Cigar Galaxy) – a possible Spiral Galaxy with visual magnitude 8.41
- NGC 2841. A Barred Spiral Galaxy with visual magnitude 9.22
- NGC 2768 – an Elliptical Galaxy with visual magnitude 9.87
- Messier 109 – a Spiral Galaxy with visual magnitude of 9.88
- Messier 97 – the Owl Nebula. A planetary Nebula with a visual magnitude of 9.9
- Messier 108 – a Spiral Galaxy with visual magnitude 10.06
- NGC 3077 – a possible Spiral Galaxy with visual magnitude 10.14
- NGC 2976. A Spiral Galaxy with visual magnitude 10.16
- NGC 2681.A Lenticular Galaxy with visual magnitude 10.29
- NGC 3198. A Spiral Galaxy with visual magnitude 10.33
- NGC 3938. A Spiral Galaxy with visual magnitude 10.38
- NGC 3184 – an intermediate Spiral Galaxy with visual magnitude 10.40
- NGC 3359. A Spiral Galaxy with visual magnitude 10.57
- NGC 3718 – a Spiral Galaxy with visual magnitude 10.61
What is a Nebula?
A Nebula is a massive cloud of gas and dust in Space.
Some Nebulae are formed when a star explodes and then dies, as is the case with a Supernova. Sometimes they can act as Star nurseries and are the areas where new Stars are forming.
The Nebulae are the spaces in between the stars referred to as interstellar space.
Images of the Nebulae have been captured using professional Space telescopes, such as the NASA Spitzer Space Telescope, operated by NASA, and the famous Hubble Space Telescope.
Messier Objects and Star Clusters
There are 9 Messier catalogued objects in the Constellation of Ursa Major:
Messiers 40; 51; 81; 82; 97; 101; 106; 108 and Messier 109.
What is a Star Cluster?
FACT: A star cluster is a large group of Stars, of which there are 2 different types:
- Globular Clusters:
A global cluster is a spherical collection of ‘Old Stars,’ numbering hundreds to millions, that are tightly bound by gravity and orbits a galactic core.
- Open Clusters:
An open Cluster is a looser formation of ‘Young Stars’ that generally has less than a few hundred Stars.
What is the Milky Way?
The Milky Way is a Spiral Galaxy, containing over 200 billion Stars, and actually forms part of the Constellation of Sagittarius.
The Milky Way itself is not a Constellation of Stars. It is the Galaxy that contains our solar system and it gets its name from the fact that it looks like a hazy swirl or river of milk across the sky, when viewed from earth. It is made up of gas, dust and stars, with spiral arms wrapped around it, and a massive black hole in the center of the Galaxy.
Not all of the Stars in the Universe are contained within the Milky Way. It is at its brightest if looking towards the galactic center in the direction of Sagittarius.
The Stars that make up the Milky Way are many light years away and cannot be individually identified by the naked eye.
Historical significance: the legends, and myths surrounding Constellation Ursa Major
In many cultures the Big Dipper asterism generates both intrigue and mystery.
For thousands of years, various cultures around the world have identified and named the constellation we know and see in the night sky as Ursa Major.
The Big Dipper asterism of the 7 main stars within Constellation Ursa Major is also referred to as ‘the Plough’, ‘the Wagon’ or ‘Charles’s Wain’. (The word Wain is a traditional word from the Mesopotamian culture).
This stellar configuration mimics the shape of the Little Dipper.
The Little Dipper is difficult to find in the night sky, and along with the North Star (Polaris) it is exclusive to the northern sky. The best way to find it is to locate the Big Dipper, which rotates around the North Star and it can be located close by.
The Babylonians also recorded details of various bright stars within the constellations in their Babylonian star catalogues before 100BCE.
The Myths
Greek mythology
There are many Greek myths and legends surrounding the origin and names of the constellations from Zeus to mythical creatures.
The Ursa Major in ancient Greek folklore is associated with Callisto, the nymph who was turned into a great bear as a punishment by Hera, the jealous wife of Zeus
The myth is as follows –Callisto was a beautiful nymph and popular with the goddess Artemis. She swore a vow of chastity to Artemis.
Callisto attracted the attention of Zeus and he fell in love with her and they bore a son Arcas. The goddess was so angry with Callisto that she banished her.
The story did not end there as Zeus has a very jealous wife called Hera.
Hera was the goddess of women, marriage and childbirth so she was so furious when she heard about Callisto’s son Arcas, with Zeus as the father, that she turned Callisto into a big bear and banished her to roam the forest for the next 15 years.
Callisto had to hide from hunters as a bear and one day her son Arcas, a hunter himself, found her, he drew his sword to kill the bear (Callisto) and at that moment Zeus intervened and sent a whirlwind to save her.
The whirlwind lifted both Callisto and his son Arcas up into the heavens and at this point he turned Arcas into the Constellation Bootes (the Herdsman) and Callisto into Ursa Major (the great bear).
There are various versions of the myth and in one Arcas is turned into the Constellation Ursa Minor.
The myth continues with Hera still being angry and begged her foster parents Oceanus and Tethys to not allow the great bear to bathe in northern waters and for this reason Ursa Major doesn’t set under the horizon in mid-northern latitudes.
Native American folklore involving the Constellation Ursa Major
Various Native American tribes have stories about hunters perusing a big bear, coyotes and wolves and even the story of seven brothers and a sister representing the main stars on the Big Dipper.
Native America assistance was important in the development of the Underground Railroad in the Mid West of America under the shine of the Big Dipper.
The Ursa Major is a significant constellation in many cultures, with different names, and meanings:
- In Latin – it means ‘greater she bear’,
- The Romans called this Constellation Arctos or Ursa.
- In Greek – Arctos meaning the ‘she bear’
- Hindu culture – the seven Rishis (meaning sages)
- In the Native American Culture it also relates to a bear
What is the difference between a constellation and an asterism?
An asterism is a group of stars that appear to form a pattern in the night sky but with no officially determined boundaries.
It can make up part of a constellation or cross the boundaries of an official constellation or even a defunct constellation.
An asterism is a more vague assembly of stars than a recognized constellation.
The meteor showers
The Ursa Major Constellation is associated with 2 meteor showers known as ‘The Majorids’.
The 2 meteor showers are:
- The Alpha Ursa Majorids
- The Leonids-Ursids
The Majorids meteor shower occurs between October 12 and October 16, with its peak around October 3 each year.
It is a relatively minor meteor shower, with the rate averaging less than one per hour.
Quick Facts about Phoenix and Constellations – Did you know that?
- The Constellation of Ursa Major is not one of the 12 constellations of the Zodiac.
- The Constellation of Ursa Major is one of the original 48 constellations identified by the Greek Astronomer Ptolemy.
- Constellation Ursa Major ranks as the 3rd largest Constellation in the night sky and occupies 3.10% of the night sky
- The flag of Alaska depicts an image of the Ursa Major Constellation
- In various Asian countries such as China and Japan, the Big Dipper is called the ‘North Dipper’.
- Alternative names for the Big Dipper include Arctos; Charles’s Wagon; The Plow; The Septentriones or the Helice.
- The Constellations are not part of the solar system; they are groups of stars that appear to form shapes that are visible from Earth.
- The largest Constellation is called Hydra and the smallest Constellation is called Crux.
- The Sun does not belong to any constellation.
- A Constellation does not actually exist as a fixed object, it is a group of bright stars that happen to be in a random place and are light years apart and ever moving. We see the pattern of their presence.
- The center of a Galaxy does not contain a Giant Star it contains a massive Black Hole.
- Red Dwarf is not a Dwarf Planet it is a Star. Most common Stars are Red Dwarf (cool Stars)
- Spiral Galaxies make up about two thirds of all the Galaxies in the Universe
Commonly Asked Questions
Q. What is the celestial sphere?
A. In astronomy and navigation terms, the celestial sphere is imaginary.
This virtual sphere has a large radius that is concentric with Earth.
We can imagine all objects in the night sky as being projected upon the inside of this celestial sphere, as if it was images placed inside a dome.
Q. What prevents us seeing the Stars and Constellations in the night sky?
A. Light pollution, fog, city lights and artificial lights all limit our visibility of the objects in the sky at night.
The best views come from outside of cities where light pollution is less. Camping in the countryside is one of the best ways to get a better view of what’s up there in Space.
Q. Will the Constellations change over time?
A. Constellations are continually on the move.
The images we form in our imagination to make objects, shapes and patterns out of the constellations have already shifted over time.
As we view the night skies from Earth they are likely to continue to do so and possibly in time the images may look very different.
IMAGE SOURCES:
- Shannon Kennedy – https://www.govloop.com/find-your-constellation-of-data/ursa-major-constellation
- The Big Dipper by Bob King – https://www.astronomytrek.com/step-6-interesting-facts-about-ursa-major-1
- Stellarium – https://in-the-sky.org/data/constellation.php?id=85
- https://lovethenightsky.com/ursa-major-constellation-guide
- https://www.nasa.gov/feature/goddard/2017/messier-81
- https://www.nasa.gov/feature/goddard/2017/messier-101-the-pinwheel-galaxy
- https://www.nasa.gov/feature/goddard/2017/messier-82-the-cigar-galaxy
- https://en.wikipedia.org/wiki/NGC_2841
- By ESA/Hubble, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=25506229
- By Sloan Digital Sky Survey – http://skyserver.sdss.org/dr14/SkyServerWS/ImgCutout/getjpeg?
- Messier 97 – https://www.stargazer-observatory.com
- By Sloan Digital Sky Survey – https://en.wikipedia.org/wiki/Messier_108
- NGC_3077 – By en:NASA, en:STScI, en:WikiSky – en:WikiSky's snapshot tool
- NGC_2976 – By Pablo Carlos Budassi – Own work, CC BY-SA 4.0,
- NGC_2681 – By Sloan Digital Sky Survey – http://skyserver.sdss.org/dr14/SkyServerWS/ImgCutout/getjpeg?
- NGC_3198 – By en:NASA, en:STScI, en:WikiSky – en:WikiSky's snapshot tool
- NGC 3938 – By Adam Block/Mount Lemmon SkyCenter/University of Arizona – http://www.caelumobservatory.com/gallery/n3938.shtml, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17929147
- NGC 3184 – CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=1427846
- NGC 3359 – By en:NASA, en:WikiSky – en:WikiSky's snapshot tool – [1], Public Domain, https://commons.wikimedia.org/w/index.php?curid=7807382
- NGC 3718 – Martin Pugh (Heaven’s Mirror Observatory) – https://apod.nasa.gov/apod/ap130803.html