Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

December 31, 1997
See Explanation. Clicking on the picture will download the highest resolution version available.

NGC 5307: A Symmetric Planetary Nebula
Credit: H. Bond (STScI) & R. Ciardullo (Penn State), WFPC2, HST, NASA

Explanation: Some stellar nebulae are strangely symmetric. For example, every major blob of gas visible on the upper left of NGC 5307 appears to have a counterpart on the lower right. This picture taken by the Hubble Space Telescope was released last week. NGC 5307 is an example of a planetary nebula with a spiral shape. Spiral planetary nebulae are thought to be caused by a bright central white dwarf star expelling a symmetric wobbling jet of rapidly moving gas. It takes light about 10,000 years to reach us from NGC 5307, and about 6 months just to go from one side to the other. In contrast, light takes only about 8 minutes to reach Earth from the Sun.

Tomorrow's picture: The Largest Rock Known

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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