It is one Star among the thousands of millions of stars. The system of stars that includes our Sun is called Galaxy, and is very vast. It is the second largest known Galaxy in the space. The largest Galaxy we know of is called Andromeda. The Sun with its family of planets, moves slowly around the centre of Galaxy and it takes 225 million years to complete one journey.

The planets move round the Sun in orbits and stay in their orbits due to gravitational force of the Sun and similarly, the moon orbits the Earth and moon's orbit is not a circle, but an ellipse. The moon also has gravitational force, which affects the earth. It causes the oceans to move , resulting in daily tides. Earth's gravity is stronger than that of the moon's (the moon is 3475 kms india and is half a million kms away from earth), since the earth is more massive. The Sun's gravity is even greater and holds all the planets in their elliptical path around itself.

Moon, like the planets, does not have light of its own, but reflects some of the light from the Sun. At any moment , half the Moon is lit up by the Sun. But at different stages of the moon's orbit, different amounts of lighted area can be seen from the Earth. Sometimes, the entire half of the moon shining with reflected light of the Sun faces the Earth. This is called a "Full Moon". At other times, only a thin strip or the lighted half of the moon can be seen. This is called a Crescent Moon. The different appearance of the moon as seen from the earth are called the phases of the Moon. Moon passes through all it's phases in 291/2 days (known as one lunar month) and they are so regular that they have been used for measurement of time. When the Moon lies roughly between the Earth and Sun, the far side of the Moon, which cannot be seen from the Earth is lit, Moon becomes invisible to us and this called the "NEW MOON". The growing or waxing period between New Moon to full Moon is known as "Shukla Pakhsha" and the waning period from Full Moon to New Moon is known as "Krishna Pakhsha" according to Indian calendars. Moon takes less than one lunar month (29 1/2 days) to complete it's one orbit round the Earth i.e. it takes 27 1/3 days (it also takes 27 1/3 to move around it's own axis).

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