In the very largest amateur instruments (say, 12″-36″ aperture) some observers report seeing tinges of red or blue in bright emission nebulae like the Orion Nebula (M42). I’ve never looked through anything bigger than an 8″ f/5 RFT, so I’ve never seen color in any deep sky object.

The exception is stars, the bright ones sometimes show color even in relatively small ‘scopes. Although stars are not intrinsically very colorful–they range from blue-white, to white, to yellow, orange, and sometimes pale red, the color of a black body radiator at increasingly lower temperatures. The faint ones all look white, regardless of their real color. There are a few stars, the “carbon stars”, that appear visually a deep red or garnet, due to materials in their atmospheres that tint the light. As an amateur yourself, you’ve probably seen some double stars with beautiful color contrasts, but that is mostly a physiological effect: the human brain distorts contrasting colors for point sources of different color very close together. Double star observers often report combinations like “green and gold”, or “pink and topaz”, but its all in their minds.

The only exception I can think of to this general rule in deep sky objects are the so-called planetary nebulae (gas shells surrounding aging main sequence stars.) These objects are often quite bright, and the light is usually concentrated in a point source or near-stellar appearance, and they sometimes appear blue from the ionized oxygen lines of the gas shells that surround them. This is real, not a physiological effect.

As I’ve gotten older, I’ve noticed that some of the bright blue planetaries of my youth now appear greener than I remember then. I understand this is due to a natural yellowing due to aging of the lens in the eye. Getting old sucks in so many different ways.

Planetary nebulae are the butterflies, or if you prefer, the sea slugs, of the astronomical zoo. No two are alike and they are all very colorful in big telescope images. Do a Google images on “planetary nebula” for some outrageous, but typical examples. Of course, you’ll never see anything like this through an amateur ‘scope.

Still, there is something to be said that you are looking at real photons emitted by real physical processes in distant regions of the galaxy. Its a thrill no photograph or digital image can give you.

It is thought that the surfaces of these dust grains form a substrate upon which atoms find shelter from the radiation and form complex compounds, even organics, like water, carbon dioxide, ammonia, methane, alcohol, urea, and many others. About a hundred compounds have been identified spectroscopically in these stellar nurseries. Our sun, and life, were formed in a place like this.

This is why there is so much interest in capturing pristine meteoritic and cometary material. These are the mechanism by which these organics are transferred from the interstellar medium to planetary surfaces. “Real primordial stuff”.

Its not just a pretty picture. We are looking at the birthplace of creation here, the lathe of heaven. And everything I have mentioned in this post has been learned since I became an astronomy student in the 1960s. It’s an exciting time to be alive.

The little red smears in the galaxy map below are other molecular clouds and HII regions like the one in Rob’s post.