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.

October 21, 1997
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

The Butterfly Planetary Nebula
Credit & Copyright: J. H. Hora & W. B. Latter (U. Hawaii), 2.2-m Telescope, Mauna Kea

Explanation: As stars age, they throw off their outer layers. Sometimes a highly symmetric gaseous planetary nebula is created, as is the case in M2-9, also called the Butterfly. Most planetary nebulae show this bipolar appearance, although some appear nearly spherical. An unusual characteristic of the Butterfly is that spots on the "wings" appear to have moved slightly over the years. The above picture was taken in three bands of infrared light and computationally shifted into the visible. Much remains unknown about planetary nebulae, including why some appear symmetric, what creates the knots of emission (some known as FLIERS), and how exactly stars create them.

Tomorrow's picture: Antennae Galaxies

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