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Credit & Copyright: Josep Drudis   
   
 
Explanation:
Braided and serpentine filaments of glowing gas   
suggest this nebula's popular name, The Medusa Nebula.   
   
Also known as Abell 21, this Medusa is an old   
planetary nebula   
some 1,500 light-years away in the constellation Gemini.   
   
Like its mythological   
namesake, the nebula is associated with a dramatic transformation.   
   
The planetary   
nebula phase represents a final stage in   
the   
evolution of low mass stars like the sun   
as they transform themselves from   
red giants   
to hot white dwarf   
stars and in the process shrug off their outer layers.   
   
Ultraviolet   
radiation   
from the hot star powers the nebular glow.   
   
The Medusa's transforming star is the faint one near the center   
of the overall bright crescent shape.   
   
In   
this deep telescopic view,   
fainter filaments clearly extend   
above and right of the bright crescent region.   
   
The Medusa Nebula is estimated to be over 4 light-years across.   
   
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: planetary nebula
Publications with words: planetary nebula
See also:
- APOD: 2025 August 31 Á NGC 7027: The Pillow Planetary Nebula
 - APOD: 2025 August 22 Á A Tale of Two Nebulae
 - APOD: 2025 August 5 Á NGC 6072: A Complex Planetary Nebula from Webb
 - APOD: 2025 July 29 Á A Helix Nebula Deep Field
 - APOD: 2025 July 13 Á Planetary Nebula Mz3: The Ant Nebula
 - APOD: 2025 June 9 Á Between Scylla and Charybdis: A Double Cosmic Discovery
 - APOD: 2025 May 14 Á NGC 1360: The Robins Egg Nebula
 

