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 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. Authors & editors: NASA
Technical Rep.: Jay Norris. Specific rights apply. A service of:
LHEA at NASA/ GSFC &: Michigan Tech. U.