Medusa was a terrifying Gorgon from Greek mythology; if you looked at her face you would be turned into a stone statue. Medusa is also the name of a planetary nebula: a radioactive core surrounded by shrouds of gas. This nebula has been photographed in more detail than ever before, and the result is beautiful.
This stunning picture was taken by the European Southern Observatory's Very Large Telescope in Chile. The image processor even corrects blurring in the image that results from the rotation of the Earth.
The Nebula is located in the Gemini constellation and is around 1,500 light-years from Earth. Medusa is roughly four light-years across in diameter, but despite this epic size, it is actually rather hard to see from Earth since it's quite dim.
To give you an idea of how far stellar imaging has come, here's one of the previous images of the Medusa Nebula.
Image credit: Jschulman555 / Wikimedia Commons
A planetary nebula has nothing to do with planets. Instead, they occur at the end of a sun-like star's life. (Maybe our future great-grandchildren will have their Earth-sky illuminated with a magical, multicolored nebula.) The star eventually swells up to an enormous size and is now called a red giant. The red giant slowly loses grip of its outer layers of gas, and they float away into space, riding on solar winds.
The remaining gas that surrounds the star gets ionized by the radioactive core of the star. The radioactive emissions from the core ionize the surrounding gas, which then glows beautiful colors depending on what element it is. The red glow comes from hydrogen gas, and the green light is from oxygen gas.
Image Credit: Zooming out, the wide-field view of the Medusa Nebula by the Digitized Sky Survey 2 / ESO
Here is the image in its entirety:
Image Credit: Medusa Nebula via ESO
[Via Press release]