A parade of PLANETARY NEBULAE

Stuart Atkinson seeks out six of the loveliest examples of these deep-sky objects for you to track down in the late-summer skies.

- Stuart Atkinson

One of the most fascinating facts I ever learned about astronomy is that stars don't last forever: like us, they are born, live a life and eventually die. Okay, so those lives are rather longer than ours, but every single star in the sky is on borrowed time.

Thanks to science fiction, a common misconception is that all stars die in cataclysmic explosions, like the Death Star. The largest do, becoming supernovae that can briefly outshine a whole galaxy, while the smallest ones just shrink and fade away, like forgotten pop stars. In between, the quieter, less attention-seeking stars the size of our own Sun - that is, with diameters of a million kilometres or so - die like celestial souffles, swelling up and then shrinking again; but not before they pop, puff off their outer layers like colourful smoke rings and surround themselves with beautiful shells of gas and dust. Because through the eyepiece these shells have a resemblance to planets, they are known as planetary nebulae'.

Planetary nebulae are important scientifically because they allow us to study the evolutionary processes of stars similar to our own Sun, and see into its future. By studying them at different wavelengths, we can explore the amount and composition of the dust and gas inside their shells, allowing us to understand better what stars are made of. It's even possible to watch the material inside a planetary nebula's shells expanding, by taking multiple images over long periods of time and comparing them. We won't be around to see what happens to the Sun as it nears the end of its life, but studying planetary nebulae allows us to jump in a TARDIS and travel into the future to do just that.

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