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Credit & Copyright: Denis Priou  
  
  
Explanation:
Galactic or  
open star clusters  
are young.  
  
These swarms of stars are born together near the plane of the Milky Way,  
but their numbers steadily dwindle as cluster members are  
ejected by galactic tides and gravitational interactions.  
  
In fact,  
this  
bright open cluster, known as M46, is around 300 million years  
young.  
  
It still contains a few hundred stars within a span of  
30 light-years or so.  
  
Located about 5,000 light-years away toward the  
constellation  
Puppis, M46  
also seems to contain contradictions to its youthful status.  
  
In this pretty starscape,  
the colorful, circular patch above and right of the center of M46  
is the planetary nebula NGC 2438.  
  
Fainter still, a second planetary nebula, PK231+4.1,  
is identified  
by the box at the right and enlarged in the inset.  
  
Planetary nebulae are a brief, final phase in the life of a sun-like  
star a billion  
years old or more,  
whose central reservoir of hydrogen fuel has been exhausted.  
  
NGC 2438  
is estimated to be only 3,000 light-years distant, though, and  
moves at a different speed than M46 cluster members.  
  
Along with its fainter cohort, planetary nebula NGC 2438 is likely  
only by chance  
appearing near our line-of-sight to the young stars of M46.  
  
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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: open cluster - planetary nebula - M 46
Publications with words: open cluster - planetary nebula - M 46
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 7 Á The Double Cluster in Perseus
 - 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
 

