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Ring Nebula

June 9, 2010

The death of a star like the Sun is majestic and beautiful. For a while, the star surrounds itself with an iridescent cocoon of hot gas and dust. Until it dissipates into the vastness of interstellar space, this cocoon shines brightly enough to see across thousands of light-years.

One of the best-known examples is in the constellation Lyra, the harp. Its brightest star, Vega, is in the northeast at nightfall. The remains of a star that was once like Vega stand to its lower right: the Ring Nebula.

You need a telescope to see the nebula, but only because it's thousands of light-years away. If you moved it to the distance of our closest stellar neighbors, it would outshine all the stars in the night sky. And it would be so big that you'd need your whole hand to cover it up.

The nebula began forming thousands of years ago. As the star aged, changes in its core caused its outer layers to puff in and out. Eventually, these pulsations drove off the outer layers of gas, leaving behind only the hot, dense core -- a white dwarf. Ultraviolet energy from the dwarf lights up the surrounding gas like the inside of a fluorescent bulb.

Today, the nebula is more than a light-year wide. Seen from Earth, it looks like a pool of blue-green water surrounded by a yellow and pink ring. But it may actually be shaped like a barrel or even an hourglass, and we're looking at it from the top -- a final blaze of glory for a once-mighty star.


Script by Damond Benningfield, Copyright 2010


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