It is well established that the earth orbits the sun, rather than the other way around as had been believed previously. Copernicus was not strictly speaking the first to suggest a heliocentric rather than a geocentric model for our solar system, albeit he is the most well-known astronomer to suggest it. However, if the earth and the other planets go around the sun, is the sun stationary in space? Or is it going around something as well in turn?

The answer is that yes, it is going around something, and not slowly either! The sun orbits the centre of our galaxy, the Milky Way, pulling us and all the other bodies in the solar system along with it at a breakneck speed of about 230km every second. Even at this speed, however, the sun takes around 225 million years to make one complete turn round the centre of the galaxy. The Milky Way is enormous, around 100,000 light years across. That means that light, travelling at 300,000km every second, would take 100,000 years to cross from one side of our galaxy to the other.

And what is at the centre of the galaxy? It is now thought that at the centre of every large galaxy is a massive behemoth, hiding in the light of the billions of stars that make up the galactic bulge; a supermassive black hole.

Sagittarius A*, the supermassive black hole at the centre of the Milky Way is estimated at a mass of over four million times that of the sun.