If we could see in three dimensions instead of two, we’d never have thought otherwise.
Perhaps the most famous sight of a dying star is the Ring Nebula, discovered in 1779.
At just over 2,000 light-years distant, it’s the closest dying star to Earth.
Upon observing it, Charles Messier wrote: “it is very dull, but perfectly outlined; it is as large as Jupiter & resembles a planet which is fading.”
This observation originated the misnomer “planetary nebula,” but physically originates when dying stars expel their outer layers.
Despite looking very much like a ring to our eyes, the Ring Nebula is anything but.
A huge, diffuse set of hydrogen shells surround it, showcasing recently blown-off material as the star dies.
Along our line-of-sight, lobes of low-density gas extend both towards and away from us.
Our perspective view this structure almost directly down one of its poles, explaining its ring-like appearance.
In 2013, astronomers used new Hubble data to map out the nebula’s 3D structure.
The reflective, high-density gas is all most telescopes ever observe.
But we now know it isn’t a ring at all, but also displays intricate structure, with an outer halo, inner turbulence, lobes and knots.
This may be the exact fate awaiting the Sun in our distant future.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.