<-We can gain an idea of the vastness of the Universe by tracing how the Solar System fits into it, and looking at larger and larger areas of space. The Sun is part of a galaxy,. which is part of a cluster of galaxies, which is part of the supercluster. Many superclusters make up the whole of the Universe.

Simply by looking up at the night sky we can see that the Universe of stars and space is vast. But just how big is it? How far away are the stars and the galaxies we can see with our eyes and through telescopes?

Nobody had any real idea of the distances to the stars until 1838. In that year the German astronomer Freidrich Bessel used a method called parallax to measure the distance to a star in the constellation Cygnus. The distance turned out to be 105 million million kilometres!

Light travels extremely quickly, at the fastest speed we know. Yet over such a vast distance, it takes the light from that star 11 years to reache us. Astronomers say that the star is 11 light-years away.

Other stars are up to tens of thousands of light-years away. The galaxies are even more remote. but the most remote objects of all appear to be the quasars. They lie up to 13,000 million light-years away at the edge of the observable Universe.
 
 

We can measure the distance to nearby stars by using the method of parallax. This works on the principle that a nearby object appears to change its position (P1/P2) when seen from different  viewpoints. We can view a nearby star from opposite sides of the Earth's orbit (E1/E2). From each side, the star appears in a different position against the background of the distant stars. From the amount the star appears to shift, its distance can be calculated. The distance from Earth at which the parallax of a star is an angle of 1 second (equal to 1/3600 of a degree) is called a parsec.