The Milky Way
We live in one of the arms of a large spiral galaxy called the Milky Way. The
Sun and its planets (including Earth) lie in this quiet part of the Galaxy,
about half way out from the centre.
The Milky Way is shaped like a huge whirlpool that rotates once every 200
million years. It is made up of at least 100 billion stars, as well as dust and
gas. It is so big that light takes 100,000 years to cross from one side to the
The centre of the Galaxy is very hard to see because clouds of gas and dust
block our view. Scientists think that it contains a supermassive black hole that
swallows anything passing too close.
Outside the main spiral are about 200 ball-shaped clusters of stars. Each
‘globular cluster’ is very old and contains up to one million stars. The Milky
Way belongs to a cluster of atleast 40 galaxies. The so-called Local Group has
two large spiral galaxies – the Milky Way and Andromeda.
The others are much smaller. They include two galaxies that can be seen with the
naked eye from countries south of the equator. The galaxies are called the
Magellanic Clouds, after the Portuguese explorer, Ferdinand Magellan. -ESA