Stars and Galaxies
The Universe is made of up billions of galaxies. Galaxies are
huge clusters of stars, containing millions of them, which are
held together by gravity. Our Sun is a star which looks very big
to us as it is so close to the Earth. The galaxy that the sun
belongs to is the Milky Way.
The Light Year
The distances in space is huge! The distance between planets
in a solar system is tiny compared to the distance between
stars in a galaxy. The distance between the stars in a galaxy
is millions of times smaller than the distance between
For example, the distance between the Earth and the Sun is
150,000,000,000 m and the distance to the next nearest star
is 39,900,000,000,000,000 m. To make things easier,
distances in space are referred to as light years.
A light year is the distance traveled by light in one year. One
light year is equal to 9.4605284 × 1015 meters =
Note: A light-year is a measure of distance not time.
For example, the distance between Milky Way and
Andromeda(the next nearest galaxy) is 2.5 million light years.