Tech spec Skywatcher Espirt 100ED ( 5 element )
QSI 690 CCD â€“ Unguided
L 3 x 300 seconds
RGB 2 x 300 seconds
Ioptron CEM60 Mount
From roughly 100 to 10,000 stars, all of which formed at nearly the same time.
Blue stars frequently distinguish younger open clusters. The M35 cluster on the right, is relatively nearby at 2850 light years away and relatively young at 150 million years old.
NGC 2158 at the far left is four times more distant than M35, over 10 times older, and much more compact with many more stars in roughly the same volume of space.
NGC 2158’s bright blue stars have self-destructed, leaving cluster light to be dominated by older and yellower stars. Both can be viewed towards the constellation of Gemini.