This photo on the BBC website reminded me of getting the Encyclopedia of Stars and Planets for my ninth or tenth birthday.

It’s ridiculous to think that the inner disc alone is 32 trillion kilometres across. The diameter of our Sun is 1.3 million kilometres so this thing is 24 million times bigger than the Sun.

It’s such an unfathomable size – any comparison is utterly meaningless: our Sun is to the inner disc of the Helix Nebula as a garden pea is to the Earth. I can’t even hold the twin concepts of the pea and our planet in my mind at the same time.

The diameter of the outer ring of the nebula is over three times that of the inner ring.