Light travels at an enormous speed (300 000 km/s) but even so the distances between stars
and between our galaxy and other galaxies are so vast that even light takes a long time to
travel to us from these distant objects.
As you know distances in astronomy can be measure in light seconds, light hours or light
years. Using that idea the Sun is 8½ light minutes away – that means it takes light 8½
minutes to reach us from the Sun. When we look at the Sun we are seeing it as it was 8½
minutes ago.
Light from the nearest star takes over four years to reach us which means it is over four light
years away. The Andromeda galaxy is more than 2 million light years away and the galaxy in
the top photograph (M81) is eleven million light years away while that in the bottom part of
Figure 1 (the Sombrero galaxy) is about 50 million light years away!
The table below gives the distances to some other well-known galaxies.
| Galaxy name | Distance (light years) |
| Sagittarius dwarf galaxy | 88 000 |
| Andromeda galaxy (M 31) | 2 300 000 |
| Whirlpool galaxy (M 51) | 37 000 000 |
| Sombrero galaxy (M 104) | 50 000 000 |
| Galaxy in the Virgo cluster (M 87) | 60 000 000 |
Even these distances are small compared with the distances of the galaxies shown in the next photograph. This was taken by the Hubble Space Telescope and shows a group of the most distance galaxies so far discovered. It contains over 10 000 galaxies in the constellation Fornax (below Orion) some of them over 12 000 million light years away! It is amazing to realise that the light that is reaching us now from the Sombrero Galaxy started on its journey 50 million years ago and that the view we have of the cluster of galaxies in Fornax is a view of how they looked 12 000 million years ago. What they are like now in out twenty first century we will only know 12 000 million years into the future!