The knotty halo of the Cat?s Eye

One of my favorite types of object in the sky are planetary nebulae. These are typically compact, fantastically-shaped baubles caused the winds blown from stars as they die. One of the most complex and interesting is the famous Cat’s Eye nebula (NGC 6543, seen here). It’s easy to spot in a small telescope, and with large telescope an incredible amount of detail can be seen.

What most people don’t know is that there’s more to PNe (as we in the know call them) than the bright inner region. Many have giant outer halos, too! And the one surrounding the Cat’s Eye is fantastically complex and a treat for the eye and brain:

[Click to felinopticenate.]

That stunning image is from the 2.5 meter Isaac Newton Telescope on the island of La Palma in the Canaries. The halo around the bright inner region is actually huge expanding shell of material centered on the nebula’s central star. And I do mean huge; that halo is nearly 6 light years across — 60 trillion km, or almost 40 trillion miles!

When the star first started ...

Full story at http://blogs.discovermagazine.com/badastronomy/2011/05/12/the-knotty-cats-eye-halo/