I’ve been accused of having a big head (which is literally true; finding hats that fit properly can be difficult), but even I wouldn’t have any trouble squeezing the 13 trillion kilometer (8 trillion mile) wide Necklace Nebula around my noggin:

[Click to enlarynxate.]

This Hubble image shows the so-called planetary nebula, which is the product of a dying star. Deep in the center of the ring are actually two stars circling each other. As one started to die, it puffed up, literally engulfing the other star. This spun up the larger star, and the centripetal force flung off material in a huge disk well over a light years across. As the star lost its outer layers, the much hotter inner core was exposed, flooding the gas with ultraviolet light, causing it to glow like a neon sign.

Or, more accurately, a hydrogen/oxygen/nitrogen sign, the gases highlighted in this image (shown as green, blue, and red, respectively). See the knots of pink emission in the ring? As the gas was expelled, the speed of the wind increased with time while the density decreased. This faster wind caught up with and slammed ...