The Ring Nebula, M57, is the best-known planetary nebula, a glowing shell cast off by a dying star in Lyra and seen nearly end-on, so it looks like a smoke ring.
At a glance
| type | nebula |
|---|---|
| distance from the Sun | 2,580 light-years (790 pc) |
| its light left it | 2,580 years ago |
| size in the piece | about 0.56 light-years acrossmodel |
Read off the piece’s own catalogue, the same values it draws with. Model marks a property of the piece’s galaxy model rather than a measurement.
About Ring Nebula (M57)
M57 lies in Lyra, between the stars Sheliak and Sulafat, and is easy to find in a small telescope as a pale grey oval with a dark centre. It is a planetary nebula: the outer layers of a star that has run out of fuel, expelled as the core contracted into a white dwarf. That white dwarf, faint at the centre of the ring, still floods the gas with ultraviolet light and makes it glow.
The ring is not a flat hoop. It is a thick, barrel-like shell seen almost along its axis, with fainter lobes and a large, dim halo around it. The colours in deep images are chemistry: blue-green near the centre where helium and oxygen are strongly ionised, red at the rim from hydrogen and nitrogen. Both Hubble and Webb have imaged it, Webb resolving a multitude of dense knots in the shell.
What you see in the piece
In the piece it is a small glowing cloud above the plane of the disc in the direction of Lyra; from the Sun it is a point, and it opens out only when you fly to it.
Measured or modelled
Its outline in the piece is a soft cloud at the modelled size; the ring shape itself is not modelled.
Questions
Why does the Ring Nebula look like a ring?
The shell of gas is a thick barrel or torus that we happen to see almost end-on, so we look through the thin centre and along the dense walls.
How far away is the Ring Nebula?
The Ring Nebula is 2,580 light-years (790 pc) from the Sun, so the light we see left it 2,580 years ago.