How much color should I be able to see in sky objects through a 10-inch telescope?

Unfortunately, when you look at distant galaxies and nebulae, you won’t see much color through your telescope. That’s because you’re viewing objects that are too faint to trigger your eyes’ color receptors. (This is the same reason why on Earth we see lots of color in the daytime but not much at night.)However, two classes of celestial objects — double stars and planetary nebulae — break this rule. The reason is their sizes. Stars are point sources, and planetaries typically measure less than 1 arcminute across. (As a comparison, the Full Moon spans 31 arcminutes.) So although they’re not really all that bright, their light concentrates over a small area. In astronomical terms, their surface brightnesses are high. The table below provides 10 colorful objects to observe.

COLOR TEST Here are five colorful double stars and five planetary nebulae in which you should see color; they are organized by group and then right ascension. You’ll find the positions of all these objects using Astronomy’s interactive star atlas at www.Astronomy.com/stardome
Object	Designation	Colors
Albireo	Beta (β) Cygni	Blue and gold
Achird	Eta (η) Cassiopeiae	Yellow and red
Al Rischa	Alpha (α) Piscium	Yellow and blue
Almach	Gamma (γ) Andromedae	Yellow and blue
Kaffaljidhma	Gamma Ceti	White and blue
The Little Gem	NGC 6818	Green
The Blue Flash	NGC 6905	Blue
The Saturn Nebula	NGC 7009	Blue-green
The Blue Snowball	NGC 7662	Blue
Cleopatra’s Eye	NGC 1535	Blue