Well Known Stars and Constellations

8/12/2019 Well Known Stars and Constellations

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1/7/14 Well known Stars And Constellations

www2.potsdam.edu/islamma/phys335constellations.htm

CONSTELLATIONS

AND STARSThere are about 48 old constellations. Today astronomers recognize 88 (44 in each hemisphere) dividing all ofthe entire sky.

THE GREAT BEAR AND THE SEVEN STARS

Probably the most famous group of stars is the Big Dipper. It is a part of the constellation called Ursa Major. It

resembles a bear in many civilizations. The handle of the Dipper is the tail of the bear curving away from the

bowl. It has the seven bright stars in it namely, Alkaid, Alcor & Mizar (appear as one), Alioth, Megrez, Phecda,

Merak and Dhube. Two of these that form outer wall of the bowl are called the Pointers, directed towards the

Polaris when joined in a line from bottom upward.

THE LITTLE BEAR AND POLARIS:

Five major constellations are always visible above the horizon from our latitudes: Ursa Minor, Ursa Major,

Cassiopeia, Cepheus and Draco. They all revolve once in 24 hours around the North Star and stars in these are

known as Circumpolar stars. Ursa Minor or the Little Bear is well known for being the host of Polaris,

positioned very close to the celestial north pole. Actually the Polaris revolves in radius of 1 degree about the

North celestial pole.


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Polaris is the brightest star in the Ursa Minor. It is part of 7 well known stars similar to Big Dipper. The handle in

it curves towards the bowl unlike Big Dipper.

CASSIOPEIA

Cassiopeia lies on the other side of the pole from Ursa Major, almost directly opposite the Big Dipper. One cansees the seven stars with naked eyes. Sometimes people visualize it as part of a Crown of the Egyptian queen

Cassiopeia, other people see it as an inclined chair or throne.

CEPHEUS

NEXT TO CASSIOPEIA is her husband the king Cepheus, known for some of the well-studied variable stars.

Cepheus forms a shape resembling the cap of a clown. Its wedge corner is very close to Polaris and is one of the

circumpolar stars. The brightest star in this constellation is called Aldemarin, meaning the arm. It stays close to hi

queen.

Draco, the Dragon

Another famous constellation near the North Pole is Draco meaning Dragon placed beneath the Ursa Minor. It is


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the dragon that the giant Hercules faces up to. Two known stars in it are called Etamin (tip of Dragon's head)

and Thuban in the tail (3rd last star) of the dragon. Etamin is 80 ly away.

SAGITTARIUS

The shape of a tea pot, this is a remarkable shape that appears in the night sky close to Milky way.

CORONA BOREALIS

Also called Northern Crown, Corona Borealis is a semicircle of stars. Its chief star is called Alphecca, comes

into view one and a quarter hours after Arcturus. The group of seven twinkling bright stars is a beautiful sight for

observation and enjoyment in the night sky. The entire constellation is only 15 degrees wide.

THE DRAGON

THE ORION AND ITS BRIGHT STARS

Next to the Big Dipper, Orion is the most well known constellation of all. Its shape and group of bright stars

dominate the winter sky. It contains more bright stars clustered together than any other single group. To the

ancients, the figure represented the giant Orion, placed in the heavens, in a heroic gesture holding the shield


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against Taurus the mighty Bull. The bull on the other hand, with fire darting out from its eye (marked by

Aldebaran), is about to charge with its splendid long horns. Orion stands with his right arm holding a great club

uplifted in the air, ready to strike. Over his left arm hangs a lion's skin that he holds up as a shield before him to

stop the raging bull. With a bit of imagination, it is not difficult to observe in this constellation, a colossal figure

and a story behind it.

Orion contains two of the 1st magnitude bright stars, Betelgeuse and Rigel. Betelgeuse marks the right shoulder

or armpit, while Rigel forms the left foot. First, the Betelgeuse rises, pushing its red face. Betelgeuse is a red

giant, deep red in color. It is also known as an irregular Variable star, changing its brightness but not regularly.

Rigel appears about 15 to 20 minutes after Betelgeuse. The Celestial equator lies between the two so that Rigel

is a southern hemisphere star and Betelgeuse is a northern hemisphere star. With Aldebaran, the two form a

triangle, called Winter triangle, dominating the winter sky. Except for Deneb, Rigel (1300 ly) and Betelgeuse

(500 ly) are the most distant stars to reach us. Red and cooler the enormous Betelgeuse is 17,000 times brighter

than sun. Rigel, blue-white and very hot although smaller than its sisters, nevertheless it is 150,000 times brighter

than sun. The belt of Orion is made of three dazzling stars of 2nd magnitude that are referred to as "bands of

Orion," by Job. These lie in a straight line three degrees long. The upper star (actually a double star) of the three

forming the belt, lies on the celestial equator. The three stars of Orion's belt are sometimes called "Three kings."

Hanging from the belt is a curved line of 3 stars known as sword of Orion. The central star of the sword is hazy,

what is known as the Famous Orion Nebula that exploded out as Supernova. In it lies the cluster of four stars

called Orion Trapezium, can only be seen when observed with high resolution spectroscope. The fourth star is

called Saiph. It forms one corner of the large approximate trapezium with three other stars - Betelgeuse, Rigeland Bellatrix outlining the Orion's body,. Its location forms the right knee of the mighty hunter. Bellatrix signifies a

"Female Warrior." Saiph means sword, the shape of the object obtained by extending from Dagger stars to it.

Orion is in the center of the galaxy that marches in brilliant procession across the winter sky in all its beauty and

grandeur, inspiring innumerable admirers throughout ages among host of civilizations. Orion comes into view in

October between 9 and 10 p.m. It brings the news of nightly frost of the coming winter. During November and

December, Orion is undoubtedly the most beautiful and dominating constellation in the night sky. In February,

one observes it in the southern sky at 9 p.m. In March and April, it is rushing furiously down the western sky. In

the middle of May, it is completely gone from the night sky.


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BOOTES AND ARCTURUS

The constellation Bootes is in a figure of a Kite in the sky. It rises about 8 O'clock early in March. Bootes is

easily located by the very bright star called Arcturus located in the extended arc of the handle of Big Dipper.

ARCTURUS

A bright star in the extended arc of the handle of the Big Dipper that no one will miss. Following the curve of the

handle about 30 degrees, or until you see the first brilliantly bright star. Its bright beam flowed down more than

2600 years ago upon the patient Prophet Job (Ayub in Arabic, peace be upon him) and is named by him.

About 10 O'clock in the evening of February (spring) it first appears (rises). On the 1st of March it appears 8O'clock in the evening. Arcturus is almost overhead in early evening of July. Arcturus and Capella are almost

equally bright. Arcturus is tinged with a bit of red, hinting its surface temperature colder than the sun and Capella.

Arcturus is a red giant star. It has exhausted hydrogen as its primary fuel and now relying on secondary sources

to escape extinction. Its center is much hotter than the sun, the extra heat resulted in its expansion of the size.

After a few thousand years, it may explode, forming a white dwarf. It is 37 ly away. It is approaching earth at the

rate of 2(1/2) miles per second, makes it appear ever bright or same bright and it lies in Constellation Bootes and

its brightest star. Bootes means "watcher of the bear", a title derived from its proximity to Ursa Major.

CAPELLA

It is the nearest to the north star among the 21 brightest. Draw a line through the Polaris at right angle to the

pointers, you should find Capella at 45 degrees from the polaris on the opposite side of the Big Dipper's handle.

It can also be found by a line drawn from bottom corner of the Big Dipper's Bowl on the handle side, and

passing the line through the mid point of the pointers to a distance of 50 degrees or to the first bright star.

Capella, Vega and Arcturus are brightest stars in the northern hemisphere of the sky. Capella is up above the

horizon 21 hours. This makes it possible to observe it sometime every night. Capella first appears in the evening

in August at about 10 O'clock during first part of the month and stays in the sky until June, always appearing

before midnight. In October, it rises almost exactly in the northeast just as the sun is setting.

Capella is a giant star yellow in color and 100 times brighter than the sun. Yet, it has the same surface


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temperature as the sun. It is 46 ly away from us. Never seen separately, it is a binary star, revolving around its

companion in 100 days. Wizard spectroscope has made its family secret out. One of 21 bright stars, Capella is

in Auriga constellation.

CASTOR & POLLUX

In the constellation called Gemini or the twins, two closely placed (four and a half degrees apart) bright stars

appear in the eastern gate of the horizon about the same time as Betelgeuse and Rigel. In November, the twinstars become very prominent in the early evening sky and Castor leads the way. They reach the meridian in 8

hours. Castor and Pollux were known to the ancients as exerting favorable influence during navigation. A

figurehead representing the two often formed the ship's head. The Apostle Paul, while ship wrecked in the island

of Melita, sailed from it in a ship of Alexandria whose sign was Castor and Pollux that brought a prosperous

voyage to his friends in Rome.

The constellation Gemini is the third spring sign of the Zodiac and is reputed to bring good weather in early June.

The rainy Hyades, including Aldebaran were first to disappear, followed by stormy Orion and the ill-omenedDog star with it. It is in a comparatively serene night sky, the twin stars, beloved of the sailors, shine side by side

like two eyes ever vigilant to protect the world under.

The twin stars may produce immense admiration for closeness of friendship between the two. In reality, the two

are moving in different directions without much connection or fondness to each other. Castor at 47 ly and Pollux

at 33 ly, are widely separated and are different in spectral types. Pollux is yellow like our sun while Castor is

white like Vega.

The bond between the two is not real and yet Castor has a companion star greenish yellow in color. The two are

separated by an arc of four seconds. It was a common practice of the ancients to swear by Castor and Pollux(the Gemini).

Constellation Sagittarius, also called The Milk Dipper (lies in the Milky way)

HERCULES CONSTELLATION


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HERCULES

Hercules holds a bow in his outstretched arm. Just shot an arrow to the Dragon or possibly to the bird nearby.

Hercules is located directly north of Scorpius.

FOMALHAUT (Fish) (Pisces Austrinus)

Still lower in the southern sky than Antares, the lonely star Fomalhaut is seen shining brightly. A line joining the

Pointers to the pole and extended 120 degrees beyond from the pole, it will reach close to Fomalhaut. This star

is at the end of a zigzag line of small twinkling stars that runs across the southern sky in the autumn. The small

stars represent the stream of water that Aquarius is pouring from his urn. The stream runs to the southern part of

the constellation Piscis Austrinus (Fish). And Fomalhaut means the mouth of the Fish. It rises in Autumn and

sinks in December from the night sky. Fomalhaut and Capella rise about the same time. Fomalhaut path is in a

short arc. Capella takes more than two and a half hours to rise at its meridian after Fomalhaut sinks. It is one of

the four Royal stars of Astrology. Others are Regulus, Antares and Aldebaran. Fomalhaut is never quite one

fourth way up towards the zenith from the horizon.

Fomalhaut in Piscis Austrinus

It is the farthest south of all bright stars from our latitudes. It is an autumn star appearing first in August. It gives

out 14 times brighter than sun. It is 22 ly away. It does not have a companion star. It is a lone star.


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ANDROMEDA AND PEGASUS

Daughter of Queen Cassiopeia and King Cepheus, the beautiful princess is chained to the rock, a curse due to

her mother who boasted too much of her beauty. The two constellations Andromeda and Pegasus (the flying

horse) are joined by one star at the corner of pegasus square. The two are about 100,000 ly away.

SPICA

The 15th brightest star is Spica that rises not so long after Arcturus. It rises a bit south of exact eastern point in

the sky. We can find Spica by extending the arc of the Dipper's handle through Arcturus and about 30 degrees

beyond the Arcturus. It can be located by a straight line starting at the pointer nearest Polaris passing diagonally

through the bowl of the Dipper about 65 degrees beyond the bottom of the Dipper. It is visible to the naked eye

in the middle of March at 8 O'clock in the evening.

Spica does not make a long arc like Arcturus or Capella. It stays south of the celestial equator. It takes 11 hours

for Spica to complete its journey setting in the south western horizon. It takes five and a half hours to reach the

highest point in the sky about 45 degrees from the zenith in the southern sky in May. It stays in night sky between

sunset and midnight during February through early October. In November, December and January, it shows up

in the night sky during the time between midnight and dawn. Spica lies in Virgo constellation, close to the ecliptic

which is the apparent annual path of the sun through the heavens.

Its color is bluish white, meaning its surface temperature is greater than sun, Capella and Arcturus. It is 600 times

brighter than our sun and 260 ly away from us. Spica is receding from the earth at 1 mile per second. Spica

means an ear of wheat. It is seen in the Virgo constellation where a virgin holds a spear of wheat in her hand.

VEGA IN (LYRA CONSTELLATION)

Vega appears about 3 hours after Arcturus in the north eastern horizon. Its color is bluish white sand its surface

temperature is less than Spica but much greater than Arcturus or Capella. To find Vega, draw a line from

junction of the bowl of the Dipper to the Polaris. Then draw a line from the polaris at right angle extending it

about 40 degrees to reach Vega on the same side of Dipper's handle. Vega is on the opposite side of Capella

about the pole. Vega has the distinction of being accompanied by four stars in a parallelogram. Vega like Capella

is always seen sometime in the night sky during the year. Vega is the main star in the constellation Lyra. Magical

Lyre in Orpheus hands gave music that tamed the wild beasts and chained the rivers in their courses.

Early in May, the star Vega rises at the same time that the sun sets and all summer long it is one of the brightest

stars in the sky overhead between 9 and 10 O'clock in the evening. It is above the horizon for 18 hours and thus


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rises in 6 hours after it has set.

Vega is 50 times brighter than sun and 27 ly away. One of the most interesting thing about Vega, is that our sun

together with all its planets seemed consistently journeying towards it or nearly towards it in the constellation

Lyra. Vega is approaching us at 10 miles per second. Lyra appears as vulture in some old maps. Vega means

the "swooping vulture."

DENEB (IN CYGNUS CONSTELLATION)

A little more than hour after Vega has risen, a bright twinkling star appears in the north eastern horizon at point

45 degrees from the pole. It is called Deneb that rises about the same spot on the horizon as Capella. It stays for

20 hours in the sky only obscured by day light.

The highest point a star ever reaches in its daily course is called

its meridian. A line drawn from the Polaris to Deneb and to Vega forms a right angle triangle in which Deneb liesat right angle. Deneb lies in the constellation called Cygnus meaning the Swan, an easily identifiable figure of

stretched wing flying swan in the sky. Deneb is the brightest star at the head of the figure also called Northern

Cross. In the spring when it rises in the north east, the cross is upside down. At setting in the north west, it seems

more nearly upright and Deneb at its head sets last of all in the cross. Deneb means "tail" for its position being in

the tail section of the constellation. It is sometimes called by its Arabic name Arided meaning the "hindmost."

Deneb is 60,000 times than our sun's actual brightness and 1400 ly away. It is white in color and its surface

temperature same as Vega. It is a member of a class of stars called Super Giant for being so large.

Deneb arrives in Spring in the east one hour after Vega. It rises after sunset in middle of May and sets one hourafter sunset in early March. The star at the foot of the cross is called Albireo, is a fine double star. One of them is

deep blue and the other is bright orange.

In the constellation called Cygnus (Swan), head of Northern Cross, ancients found it in the figure of Flying Swan.

Deneb means "the tail", because it appears in the tail section of the constellation Cygnus. It is an Arabic

translation of the word Arided meaning "hindmost". It is 60,000 times brighter than sun, 1400 ly away, white in

color, of a class of stars called Supergiant, appears in the middle of May (Spring) just after sunset and sets in

early part of March one hour after sunset.


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The star at the foot of the Cross is called Albireo, a fine double star. One is deep blue and the other is orange,

easily visible with the help of ordinary telescope.

ALTAIR (IN AQUILA CONSTELLATION)

About 80 degrees from the pole towards south, halfway

between Deneb and Vega, is the brilliantly bright star called Altair. It is 20 degrees directly south from Albireo at

the base of the Northern Cross. Altair is seen in the constellation Aquila meaning the eagle. Altair is the middle of

the three bright stars in a line. Altair means "the flying eagle." Altair, Vega and Deneb when joined together forms

an acute angle triangle known as Summer Triangle, with its short side towards north. Altair at its apex is in the

south.

SUMMER TRIANGLE

Altair is in Aquila or the eagle constellation. Altair means the flying eagle.

A brilliantly white (yellowish white) star located by moving down the Cross from Deneb to its tail to Albireo and

about 20 degrees more to the first bright star is ALTAIR. About 10 degrees northeast from Altair is the well

known Constellation "Dolphinus," also called Job's coffin.


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Altair rises about 8 degrees north of the exact eastern point on the horizon. An interesting figure near Altair is in

the shape of a diamond with a short tail, lying about 10 degrees northeast of Altair. This group is calledDolphinus. It has a popular name called "Job's coffin."

DELPHINUS

In the shape of a Dolphin, this constellation also called Job's Coffin consists of 5 stars. It contains a variable star,

a double star and a spectroscopic binary star.

One seldom sees Altair during the first four months of the year. It takes about 13 hours for Altair to make its

journey across the sky. Its color is white or yellowish white. Its surface temperature is less than Vega but greater

than Capella. Altair is actually 11 times more luminous than sun and 17 ly away from us. Altair is approaching the

earth at a speed of 16 miles per second.


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SCORPIUS CONSTELLATION

Constellation Scorpius meaning scorpion that stung the Orion is where Antares can be found. It is considered thehissing snake from which Spenser represents Orion as "flying fast." The mighty hunter Orion does not return to

the sky until scorpion is gone. The two Orion and Scorpion never appear together in the sky. The name Antares

signifies "Rival of Mars." When the Mars appears in the constellation Scorpius, the two red colored objects are

splendid rivals. Antares is a red giant. It is 400 ly away. It is an old star cooler than sun as the red color suggests.

Most stars get their energy from fusion of hydrogen atoms into helium. After spending all its hydrogen fuel, the

internal core tends to contract, star becomes hotter, for a brief period of its life it lives on secondary sources of

energy. The outer layers then swell up and become very luminous. After thousands of years of this spendthrift

activity, the secondary sources are exhausted. The star collapses on the inside and explode on the outside,

becoming a Nova or a new star. Gravitational forces then attract the fragments back into smaller size feebly

shining star of the type known as White Dwarfs, e.g., companion of Sirius.

ANTARES

Antares is at its highest point (meridian) in June 22nd at 10 O'clock in the evening. At its highest point, it is only

one quarter way due south from the horizon to the zenith. It is one of the south stars which always lies south of

the celestial equator. It appears farther south from Altair.

Antares is one of a binary system. Its companion has a greenish color, not easily seen by small telescopes.

ALDEBARAN

The stars described in Chapter 1 through Chapter 10 earlier, have a particular connection with the spring,

summer and autumn months. Capella shines throughout the winter, and in spring and fall as well.

There are however 6 bright stars that are distinctly of the winter. These 6 stars are Aldebaran, Betelgeuse, Regel

Pollux, Procyon and Sirius. Of these 6 stars, Aldebaran is the first to appear in September a bit north of the east

point in the horizon. It glows with rosy light, demanding attention proclaiming as one of the most importantly

heavenly bodies.


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It lies in the open end of a bright V-shaped cluster of stars known as Hyades. The cluster is the head of the well

known constellation "Taurus" the bull, named by the Greeks. It is the fiery eye of the enraged bull as he lowers

his head charging Orion. The shimmering light of Pleiades can also be shown in the same constellation Taurus.

The meaning of the Arabic word Aldebaran is the "hindmost" or the "follower" of Pleiades, as it appears directly

below Pleiades. Aldebaran shines for about 8 months in the sky every year. One hour after the deep ruby red

Antares vanishes below the western horizon, another red star Aldebaran rises in eastern horizon. The two never

can be seen in the night sky together. The two are named Royal stars in Astrology, a suggestion for royalty.

It is known as a standard 1st magnitude star. It is 70 ly away. At the distance of the sun, it would send 100 times

more light than sun. It is receding from us at 30 miles per second from us. It lies in the path of the moon and

frequently obscured from our view by moon. Such an intrusion of the moon is called "Occultation," when the

subject occulted is a planet or a star. A star disappearing behind the moon shows no sensible disk. A planet

gradually disappears. Aldebaran has a faint companion star and belongs to the group of stars called Red Giants.

It is a dying star like Antares.

THE TWO DOG STARS: SIRIUS AND PROCYON (IN CANIS MAJOR AND CANISMINOR)

Moving down the belt of Orion, about 20 degrees south, you meet the brightest star called Sirius, also called the

Great Dog Star. It is the chief star of the constellation Canis Major and hence the name. It follows the heels of

Orion in its journey in the sky. The constellation names the season dog-days, for the sizzling hot summer days

(July and August) in which its presence is made known. During this time, Sirius rises just after the sun in the

southern sky. The name Sirius comes from the Greek word scorching (hot summer) or sparkling (excessively &

brilliantly bright). Sometimes also called Orion's Dog, Sirius is referred to as brining miseries to men.


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Sirius appears in middle of November at 10 O'clock. I March and April it shines

in the southwest. It sinks with sun about the end of May.

Sirius is nearer than most bright stars, only 8 and a half ly away. It has a companion star revolving in period of 50

years.

The other Dog star Procyon lies in the constellation Canis Minor. Betelgeuse, Sirius and Procyon form an

equilateral triangle, called winter triangle. These three stars together with Rigel form almost square. Procyon is at

11 ly away. It announces the arrival of Sirius the chief. Procyon has companion star revolving at a period of 40

years.

REGULUS

Regulus is known by the shape of a sickle it forms with five other stars.

REGULUS (IN LEO CONSTELLATION)

Regulus appears above the horizon a bit north of the east about 9 O'clock in New Years day or about the

Christmas time. It is the chief star of the eastern sky until Arcturus and Vega come into sight. It is a sparkling

white star with a slight hint of blue in its color. It takes about 6 and three quarter of an hour to reach the meridian


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It shines in January through April in early part of the night sky. It sinks completely in August being at the same

place as the sun. It is 140 times brighter than sun and 77 ly away. It is found in the constellation Leo or the Lion

(one of Zodiac signs) . The blade of the sickle marks the shoulder of the lion while the Regulus lies at its heart,

sometimes named as "heart of the lion." Regulus means "Chief." Sun stays in this constellation a bit more than 5

weeks starting at 2nd week of August. An interesting star in Leo, is the tail of the lion, called Denebola.

Denebola points in the direction of another star and thus forms a double star.

The Pleiades

The Pleiades cluster (M45) is

sometimes referred to as The Seven

Sisters and appears in numerous

ancient texts including the Book of

Job "Can you bind the Chains of the

Pleiades" Job 38:31. The Japanese

call the Pleiades the Subaru and

many people (incorrectly) call it thelittle dipper because it looks like a

tiny version of the Dipper.

The Pleiades is a beautiful example of

a young open cluster. We think that

the Pleiades formed from a huge

The cluster of stars is in the interstellar dust cloud formed about 60 million years ago and is situated about 410

light years away in the direction of the constellation Taurus the Bull. The best time to view the Pleiades is from

late October to early March.

The following picture is from Prof. Martin's Web Page at: http://www.kingsu.ab.ca/~brian/astro/pleiades.htm

NUMBER OF STARS IN THE UNIVERSE

Ordinary eye sight sees about 5,000 stars in a clear night sky. The keenest of the sharp eye sight may see over

7,000 stars. Stars visible with naked eye are called Lucid Stars by the Astronomers. It is believed that there are


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about 100 billion stars in our own galaxy. The known number of galaxies is about one trillion, each of which may

have as much stars as our galaxy on the average.

It is then a tremendously enormous number of stars that are present in the known universe.

If we use a vacuum cleaner to collect the fine dust particles over the volume of size of the earth in the interstellar

space, then we will get about a cup full of these dust particles. Even such a dust can appreciably block star light

because of the intervening vast distances. For example, our Milkyway would be much brighter in the absence of

dust clouds obscuring the star light.

The number of stars catalogued by astronomers is near 800,000.

All of the brighter stars and some of the faint stars have their own names, deriving from ancient civilizations and

old mythology of ancient people. 60 of these names of the stars are used by professional astronomers. Most

such stars were used for navigation in the night time.

Many names are Arabic and Greek in nature. Achernar, the end of river; Denebola, the tail of the lion;

In many cases, a family name in Latin for the all the stars in the constellation and individual stars as Greekalphabets. In constellation Taurus, we have alpha Tauri meaning alpha of Taurus. And, Similarly we have beta or

gamma Tairi. Beginning with alpha, the star names were given according to its brightness. A major exception to

this rule is in the Big Dipper. The seven stars in it, start with Alpha and end with eta in order from the bowl to the

handle. Later, catalogues of stars were made by naming them by numbers instead of letters but preserving the

name of the constellation.

The Brightness of the Stars

Many stars appear to be faint and small due to extremely long distance. They appear like points while in realitytheir sizes are immense, emitting far more light than any bright object on earth. There is no simple relation about

the real and apparent brightness of the stars. At first, it was the naked eye that figured out the magnitude of the

brightness without regard to the distances. It was an arbitrary classification without regard to its actual brilliance

and size. In this classification there are 21 brightest stars of magnitude one, about 60 stars of magnitude 3. All the

stars visible to the naked eye were divided into 6 magnitudes, now extended to 21 magnitudes by modern

astronomers. Polaris considered 2nd magnitude star was used as a reference. But, Polaris is slightly Variable

star.

Among 21 brightest stars, there is variation in their brightness. Astronomers preserved magnitude one as a very

bright star among the brightest (example Spica .91). Star brighter than one is zero and can be negative numberfor greater brightness than zero. So, in this scale Sirius is -1.42 and Regulus is 1.36. The light ratio agreed upon

is 2.5 times higher than preceding one for increase of one order(example from 1 to 2 magnitude). Or each

magnitude of star is four tenths brighter than the next higher magnitude. This makes first magnitude stars 100

times brighter than 6 magnitude stars.

There are 21 brightest stars among billions of them scattered across the sky. They are called stars of the first

magnitude. All except three have their proper names of their own, named by people in the civilizations past. Stars

are so steadfast that they can be found in the same spot in the sky.


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The moon appears as thin crescent and goes through phase changes . The planets are wanderers moving from

place to place, changing its brightness and positions.

All of the 21 bright stars cannot be seen from our 44.5 degrees north latitudes. These six bright stars are

Canopus (230 ly away and credited to run away with one of the sisters of Pleides); Alpha Centauri (nearest the

earth, a double star); Beta Centauri (also called Hadar); Alpha Cruci, Beta Crucis, And Achernar. All six of

southern bright stars can be seen from Cuba.

NUMBER NAME OF STAR

1 Sirius

2 Canopus

3 Alpha Centauri

4 Arcturus

5 Vega

6 Capella

7 Regel

8 Procyon

9 Achernar

10 Beta Centauri

11 Altair

12 Betelgeuse

13 Aldebaran

14 Alpha Crucis

15 Spica

16 Antares

17 Pollux

18 Fomalhaut

19 Deneb

20 Beta Crucis

21 Regulus

Distance between the two Pointers is about 5 degrees. It covers about 3 inches of a ruler when held fixed at

arm's length and observing with one eye closed. Four of the planets(Venus, Jupiter, Saturn and Mars) appear

very bright in the sky and not to be confused with stars. Planets owe their brightness due to reflection of sunrays


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off their surfaces. Planets are not fixed in their positions relative to other stars. Planets do not twinkle as stars do.

Planets shine with steadier light. Planets keep their path within a short distance (a few degrees) of moon's path.

Planets are not found very far north or very far south. Venus stays within 48 degrees from sun. In the evening

sky, Venus sets no more than 3 hours after sunset. In the early hours of dawn, it never rises more than 3 hours

ahead of the sun. Venus is white, Jupiter is a little tinged with yellow, Mars is fiery red and Saturn is decidedly

yellow.

Other 16 bright stars can be identified with reference to The Big Dipper (Ursa Major), a part of the Great Bear

constellation. It consists of 6 bright stars but not brighter than 21 of the first magnitude stars. It consists of a bow

and a handle and is always seen in the clear night sky. Two stars on outer side of the bowl, called the "pointers",

so named because a line joining the two from the bottom to the top points toward the North star. The distance is

about 5 times that of the distance between the pointers. The North star marks the center about which the

Celestial sphere revolves. The position of the stars relative to one another is the same.

DOUBLE STARS:

Many stars that seemed single to our naked eye are actually double stars or group of stars. Given the enormous

distance, it seemed like one star. Also, a bright star may actually be a faint star that appears brighter because it iscloser to the earth. A single star may have a close by companion to make them appear like a double star, In

reality the two may be far apart and seen as a double star because the two appear in the same direction. Actual

grouping of two stars is fairly common in the galaxy. They are called binary star system.

RETURN TO DR. ISLAM'S ASTRONOMY PAGE

UPDATED 06/20/02
http://www2.potsdam.edu/PHYS/islamma/Phys335Astronomy.html

Well Known Stars and Constellations

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