Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. This planetary nebula , created near the final phase of a sun-like star's life , is composed of tenuous shells of gas ejected by the hot central star. The atoms of gas, stripped of electrons by ultraviolet radiation from the central star, radiate light at characteristic energies allowing specific chemical elements to be identified. In this image , emission from nitrogen is represented as red, hydrogen emission as green, and oxygen as blue.
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