What is Constellation?

A constellation is a group of stars in the form of a pattern such as Aries(Ram), Taurus(Bull) etc.. 

Each constellation covers  a region of celestial sphere.

There are 88 constellations officially recognized by the International Astronomical Union, covering the entire sky.

Circumpolar constellation

Any constellation that, from particular latitude on Earth, never sets below the horizon.

From the North Pole, all constellations north of the celestial equator are circumpolar constellations.

Hindu Constellation

Nakshatra is the term for lunar mansion(a segment of the ecliptic through which the moon moves in its orbit around the earth) in Hindu astrology. A Nakshatra is one of 27 (sometimes also 28) sectors along the ecliptic.

Nakshatra system is prevalent in India from Vedic period.

Zodiac constellation

Earth orbits our Sun once each year. Viewed from Earth, our Sun appears to trace a circular path. This path defines a plane called the plane of the ecliptic (or just the ecliptic). The zodiac is the group (or “belt”) of constellations that fall along the plane of the ecliptic. It is through these constellations that our Sun appears to “pass” during the year. While there are 12 astrological constellations of the zodiac, there are 13 astronomical zodiac constellations:  Capricornus, Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, and Ophiuchus. The annual cycle of the zodiac was used by ancient cultures to determine the time of year.

FAQ

1. Are all stars part of a constellation?

No, there are billions of stars, and only a fraction of them make up the shapes of our constellations — these are the stars that are easily seen with the unaided eye. Ancient observers connected these stars into the star pictures.

2. Why Do Most Stars and Constellations Move?

As Earth spins on its axis, we, as Earth-bound observers, spin past this background of distant stars. As Earth spins, the stars appear to move across our night sky from east to west, for the same reason that our Sun appears to “rise” in the east and “set” in the west.

3. Why north pole is stationary?

Stars close to the celestial poles, the imaginary points where Earth’s north and south axes point in space, have a very small circle of spin. So if you find Polaris, Earth’s north “pole star,” you will observe it move very, very, very little in the night sky.

4. Why Do We See Different Constellations During the Year?

If observed through the year, the constellations shift gradually to the west. This is caused by Earth’s orbit around our Sun. In the summer, viewers are looking in a different direction in space at night than they are during the winter.