Monday Bites: The Eye Of The Tiger

The Eye Of The Tiger: The Cat's Eye Nebula. 

Credit: NASA 

What you're looking at is the Cat's Eye Nebula, a planetary nebula in the constellation of Draco. The name's a misnomer, though. A planetary nebula (pl. nebulae) has nothing to do with planets. Or cats, since you wonder. Two hundred years ago, when astronomers saw these objects for the first time, they thought they were looking at planets. At the eyepiece of their primitive scopes, which were state-of-the-art in their days, these planetary nebulae emerged as tiny luminous blobs. Hence the name, planetary nebula or planet-like wisps. If you try seeing them with a small telescope, they'll appear before you as planetary spheres. Over the past couple of centuries, telescopes have gotten bigger, better, and fancier (they've always been costly). And so is our knowledge of the universe. 

Planetary nebulae are expanding bubbles of gas ejected from stars nearing death. For historical reasons, their names have survived the test of time as astronomers continue to use the term, with the slightest intention of settling for anything else. Into the penultimate lap of their life cycles, most stars swell into red giants and begin to cast away their outer layers, leaving their cores as luminous white dwarfs. Under the intense radiation of the disrobed white dwarf, the expanding cloud of gas glows as a gleaming beacon across the otherwise unlit cosmos. When seen through large telescopes, planetary nebulae show complex and intricate channels of gas flows. 

This particular image is a composite of multiple exposures gathered by the Hubble Space Telescope at different optical bands, which reveal the presence of ionized hydrogen (@ 656.3 nm), ionized nitrogen (@ 500.7 nm), and doubly ionized oxygen (@500.7 nm). Along with that, Chandra Observatory's X-ray observations highlight in blue the extremely hot gas around the white dwarf at its center.  

 This image was officially released in January 1995.