Small Blue Dot…

Look at the picture above. Do you see the small blue dot in the band of pale brown to the right? Do you know what that is? Go on guess!

I will give you a clue. This photograph was taken by a NASA spaceship called Voyager some time between February the 14th and June the 6th in 1990. It was over 6 billion kilometres away from the pale blue dot. It is now about seventeen and a half billion kilometres away on the outer edges of our solar system.

Of course, the pale blue dot is Earth. The coloured bands are artefacts caused by the light from the sun interfering with Voyager’s optics. Carl Sagan (of whom there is a picture in my lab) wrote a book in 1994 called ‘Pale Blue Dot’. In it he wrote…

From this distant vantage point, the Earth might not seem of particular interest.
But for us, it’s different. Look again at that dot. That’s here, that’s home, that’s us.
On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.
The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

He was a great writer and he has brought science to life for many. He is worth reading if you get the chance. I think that I erroneously said in class that the lines you see in the picture are Saturn’s rings. That is incorrect and Voyager had visited Saturn a decade earlier – this picture was from much further away. Saturn is only about 1.5 billion km away from the Sun (about 10 astronomical units/AU – the average distance from the Earth to the Sun).