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Let us Make Friends with Stars The bright twinkling stars challenge you to fit any pattern that you can imagine and weave your own stories about them. As I told you earlier, there are many mythological stories attached to these stars and constellations. Zodiacal constellations. 
Let us open the story book and read on about other stars and
constellations.Let us start with Dhruvtara (pole star). How dowe locate it in the sky? Constellation Ursa Major help us. It is an easy constellation to identify. There are 7 bright stars, four of them making a quadrangle and 3 others making trailor, a handle or a plough. The 7 stars form parts of a big bear in the sky, called the great bear and the 3 others make the tail. The other faint starts making the rest of the body and the face of the bear. According to Indian mythology, Ursa Major is called ' Sapta Rishi' or seven sages. The sages - Kratu, Pulaha, Pulasya, Atri, Angira, Vasistha and Marichi find a place of prominence in the sky. But during winter, we have to look for some other constellation to locate the pole star as Ursa Major is a summer constellation. From October to March, we can use 'Cassiopia' constellation. Five bright stars of this constellation make the letter M or W of the English alphabet. In ancient mythology, Cassiopia was an Ethiopian queen. She was very beautiful and very proud. She disregarded the sea nymphs. To display her contempt for them she placed her throne on the sea shore. As a result of general discontent, God ordered that Cassiopia's chair would always appear in the tilted fashion. Doesn't it look like a tilted chair? In Indian Astronomy, it is called Sarmishta. Cassiopia and Ursa Major also make a good celestial clock. We have located the pole star and so we have got our orientation. What next? The whole sky is there for you to explore. Let us first learn about latitudes and longitudes of stars on the celestial globe, which will help us in locating stars, constellations and other heavenly objects.  Latitudes and Longitudes on Celestial Globe Declination and Right Ascention Latitude on the celestial sphere is called declination and longitude is called Right  Ascention.
The circle drawn from celestial North Pole through the star is called
its hour circle. The longitude of a star is the angle between its hour
circle and the position of Vernal equinox, measured in the anticlockwise
direction i.e., opposite to the direction of diurnal Celestial equator
is divided into 24 hours, each minutes into 60 seconds. Declination and
Right Ascention of a star. Declination and Right Ascention of a star
remains the same, wherever we are on earth.A star which is at the position of Vernal equinox would have Right Ascention of 0 degree and declination of hour angle XXIV or 0 degree. Horizon System Do you want to know a local system? The local system is called the horizon system.  the
height of a star from the observer's horizon is called its altitude. If
you are standing at Delhi, the altitude of pole star would be equal to
the latitude of Delhi i.e. 28.65 degree.The angular distance between the star and pole star (measured eastwards) as viewed by the observer is called Azimuth. Wherever you are, Azimuth of pole star is zero. Altitude and Azimuth of other stars depend upon the observer's position on the earth. Star Maps: You are given a set of four sky maps to help you. They show the constellations around the Northern celestial pole, constellations around the Souther celestial pole and those between hour angle 24 (XXIV) and 12 (XII) and between 12 (XII) and 24 (XXIV). Refer to the maps. In the figure showing the North Polar chart you can see the constellations around the pole star. 1 is Ursa minor whose tail end is pole star. From 1, move to 2, Ursa Major and 3 is constellation Auriga. Then move to Perseus (4), to Cassiopeia (5), to Cygnus the swan (6), to Bootes (7) Leo (8), Cancer (9), Gemini (10), Taurus (11), Aries (12), Pisces (13) and to Pegasus (14). Some of these constellations are seen completely in the star charts showing the constellations on both sides of the celestial equator from hour angle 0 degree to XXIV. In the next figure of south polar star chart, the constellations around the South pole of the celestial globe are shown. There is no pole star in the southern hemisphere. Some of the important constellations are Scorpius (15), Sagittarius (16), Pisces, Austa, the southern fish (17), Phoenix (18), Centaurus (19), Canis Major (120) and Crux (21) southern cross. The next two star charts show the constellations from hour angles XXIV to XII and XII to XXIV respectively. Hour angles XXIV to XII : From Pegasus (14) move to Cygnus (6), Hercules (22), Bootes (7), Virgo (23), Libra (24), Eiuchus, the serpent bearer (25), Aquriala, the eagle (26), Aquarius (27), Capricornus (28), Sagittarius (16), Scorpius (15), Centaurus (20), Telescopium (29), and Pisces Aust (17). Hour angles XXIV to XII : From Pegasus (14) move to Cygnus (6), Hercules (22), Bootes (7), Virgo (23), Libra (24), Eiuchus, the serpent bearer (25), Aquriala, the eagle (26), Aquarius (27), Capricornus (28), Sagittarius (16), Scorpius (15), Centaurus (20), Telescopium (29),and Pisces Aust (17). Hour angles XII to XXIV : Start from Ursa Major (2),move to Auriga (3), perseus (4), Andromeda (30), Aries (12), Taurus (11), Gemini (10), Cancer (9), Leo (8), Orion (31), Pisces (13), Phoenix(18), Canis Major (19) and to Vela, the Sails (32). The four star charts show the imaginary figures representing the constellations. The next set of 4 sky maps are of winter, spring, summer and autumn, which help you identify some of the important and prominent constellations. Winter Sky In the winter sky, you can see a band of 3 bright stars. They belong to constellation 'Orion', a prominent constellation of the winter sky. It is also called 'hunter' and the band of 3 bright stars forms the belt. The star on the shoulder of Orion is 'Andra' or 'Betelgeuse' while the one near the knee is 'Rajanya' or 'Regel'. When you go straight down, about four times the length of the belt, you will find the brightest star of the sky - Sirius in the constellation 'Cenis Major'. It you go in the opposite direction, you will see a bright red star - Aldebaran in the constellation 'Taurus'. The raddish Aldebaran belongs to the interesting zodiacal constellation Taurus. The V-shaped constellation forms the head of the bull. The Indian name in 'Vrishabha'. Around 4000 years ago, Vernal equinox was in the Taurus constellation. This constellation includes two star clusters, 'Pleiades' and 'Hyades'. Some stars which are very tightly packed in a small region appear as clusters. Clusters can be globular or open. Globular clusters have many hundreds of stars and open clusters have a few hundered stars. Pleiades and Hyades are open clusters.  |
