“A bit of mould is a pleiad of flowers; a nebula is an ant-hill of stars.” -Victor Hugo

Nothing lives forever, not even the stars. Our Sun, like all true stars, thrives on nuclear fusion in its core.

A star reaching the end of its life goes from fusing nuclei to blowing off its outer layers and contracting down. Image credit: NASA, ESA, and A. Zijlstra (The University of Manchester); Acknowledgment: J. Barrington (Hubble’s Hidden Treasures Competition).

At millions of degrees, it converts hydrogen into helium, and will later heat up further, fusing helium into carbon.

The gaseous outer layers of a Sun-like star glow in space after being expelled as the star reached the end of its life.

Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA).

Like most stars, it will never get hot enough to go supernova. When it runs out of fuel, it will contract into a white dwarf, blowing off its outer layers, forming a planetary nebula.

The planetary nebula NGC 6369’s blue-green ring marks the location where energetic ultraviolet light has stripped electrons from oxygen atoms in the gas. Image credit: NASA and The Hubble Heritage Team (STScI/AURA).

This example of cosmic recycling will send both hydrogen and heavier elements back into the interstellar medium.

Planetary Nebula M2–9, from the Hubble Space Telescope. Image credit: Bruce Balick (University of Washington), Vincent Icke (Leiden University, The Netherlands), Garrelt Mellema (Stockholm University), and NASA/ESA.

Stars up to 800% the mass of the Sun will achieve this fate, with planetary nebulae taking on a variety of morphologies.

Four individual planetary nebulae — He 2–47, NGC 5315, IC 4593, and NGC 5307 — were imaged by Hubble in February of 2007. Image credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA).

Single stars may blow off their outer layers spherically, like 20% of planetary nebulae.

The Eight Burst Nebula, NGC 3132, is not well-understood in terms of its shape or formation. The different colors in this image represent different temperatures. Image credit: The Hubble Heritage Team (STScI/AURA/NASA).

Stars with binary companions may produce spirals or other asymmetrical shapes.

The intricate, layered, asymmetrical shape of a planetary nebula like the Cat’s Eye Nebula suggests a binary companion. Image credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA); Acknowledgment: R. Corradi (Isaac Newton Group of Telescopes, Spain) and Z. Tsvetanov (NASA).

Most commonly, bipolar nebulae may originate from rapidly rotating stars.

Nitrogen, hydrogen and oxygen are highlighted in the planetary nebula above, known as the Hourglass Nebula for its distinctive shape. Image credit: NASA/HST/WFPC2 R Sahai and J Trauger (JPL).

The most spectacular images of this natural phenomenon come from Hubble, which assigns different colors to individual elements, temperatures or spectral features.

The Ant Nebula, also known as Menzel 3. Image credit: NASA, ESA & the Hubble Heritage Team (STScI/AURA); Acknowledgment: R. Sahai (Jet Propulsion Lab), B. Balick (University of Washington).

In another 7 billion years, our Sun will die in this manner, like only one-in-four stars in our Universe.