The Veil Nebula (Foraxx)

The Veil Nebula is what remains of a star that tore itself apart in a supernova between ten and twenty thousand years ago. All that time later, the explosion is still unfolding, its expanding shock wave racing through the gas between the stars. The delicate filaments scattered across Cygnus mark the places where that shock slams into the surrounding material, heating it until it glows.

At first glance it looks like a collection of disconnected wisps, but it’s actually a single enormous shell of gas, several times wider than the full Moon appears in our sky. Most of what we see are the thin edges of that bubble viewed almost side-on, which is why the Veil has those remarkably fine, tangled strands instead of the soft, cloudy appearance you might expect.

Its colours aren’t artistic licence, either. The blue-green glow comes from doubly ionised oxygen, while the reds are hydrogen, each lighting up under different conditions as the shock wave passes through. If you look closely, many of the filaments almost seem to be woven together, tracing different gases responding to the same violent event.

Astronomers split the complex into several familiar sections: the Western Veil, better known as the Witch’s Broom; the larger Eastern Veil; and the intricate web of fainter filaments between them called Pickering’s Triangle. They’re all part of the same expanding remnant, just different pieces of a much larger structure.