Looking up in to the night sky it’s not difficult to see why the ancient Greeks believed that all the stars in the night sky were fixed on a celestial sphere revolving around the Earth and other planets. From our view on Earth the stars appear to be at a fixed distance in the sky rotating with the seasons and never changing their positions relative to each other, rising in the east and setting in the west. However, we know now that the Earth is not the centre of the cosmos but a tiny world in an expanding Universe. So from Earth how far can we see and which star is the farthest?
This is a question which does not have one simple definitive answer. We know that the Sun is the closest star to us at 150 million km (93 million miles) away. However, when it comes to the farthest star there are a few more variables that can be considered.
Stars on fixed celestial sphere surrounding the Sun and planets. (Image credit: Wikimedia.org)
Farthest star visible with the unaided eye
Under today’s light polluted skies the most distant star that can be seen without any great ...