The Cat’s Eye Nebula, NGC 6543, is a planetary nebula in Draco, the first whose spectrum was taken, proving that such nebulae are glowing gas and not stars.
At a glance
| type | nebula |
|---|---|
| distance from the Sun | 4,450 light-years (1.36 kpc) |
| its light left it | 4,450 years ago |
| size in the piece | about 0.33 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 Cat's Eye Nebula
When William Huggins turned a spectroscope on NGC 6543, he saw not the continuous rainbow of starlight but a few bright emission lines. That single observation showed that planetary nebulae, and nebulae like them, are clouds of hot, thin gas rather than unresolved swarms of stars. One of the lines belonged to no element then known; it was later traced to ionised oxygen in conditions impossible to reproduce on Earth.
Hubble images made the nebula famous for its intricate structure: overlapping bubbles, jets, knots and, around them, a series of faint concentric rings. Those rings are thought to be shells puffed off by the star at regular intervals before the main nebula formed. X-ray images from Chandra show the central cavity filled with gas heated by the star’s fast wind.
What you see in the piece
In the piece it is a small cloud of glowing gas high above the plane of the disc, towards the north pole of the ecliptic; from the Sun it is only a point.
Measured or modelled
The cause of the regular outer rings, and of the nebula’s twisted inner shape, is still debated; a companion star is a common explanation.
Questions
Why is the Cat’s Eye Nebula important?
It was the first planetary nebula whose spectrum was observed, and its bright emission lines proved that these nebulae are made of glowing gas.
How far away is the Cat’s Eye Nebula?
The Cat’s Eye Nebula is 4,450 light-years (1.36 kpc) from the Sun.