I attended a star party in Wisconsin this past weekend during the prime of the fall color season. On the way down I pulled the car over more than once to take photos of the breathtaking maples and oaks set among dark pines. Our eyes delight in natural color. It gets a little motor spinning in the brain. Bright colors in nature jump out from the norm of brown, white, gray and green. And the more vivid and intense the hues the greater our delight.
Looking at photos of nebulas and galaxies we’re similarly struck by the incredible reds and greens of nebulae, the pink knots of star formation in a galaxy’s spiral arms and blue hues of starlight reflected in cosmic dust. But in real life, when gazing through a telescopes, these colors are nearly always absent. Almost everything appears in shades of gray even in larger amateur telescopes that most of us can’t afford.
There are exceptions. Planets show shades of pink, red, yellow and even blue as do the brighter stars. A precious few of the brightest nebulae, including the famous Orion, glow green and red, but these hues are subtle and come nowhere near what photographs reveal. The brightest planetary nebulae, a group of nebulae named for their small, round shapes resembling planets, glow pale green and blue. Everything else appears in fuzzy shades of gray. The night sky is a black-and-white paradise.
To appreciate the muted colors in astronomical objects you’ll need at least a 6- or 8-inch telescope. That’s generally where beginners start when buying a good scope, so beyond the planets and moon many are disappointed when they get their first look at everything else — galaxies, nebulae and even star clusters — they’ve grown accustomed to seeing in photographs.
Don’t curse your telescope. It’s just biology. Everything really does glow red, green and gold as Christmas but just not with enough intensity to activate the cone cells in our retinas that sense color. Instead, rod cells do the work. They’re excellent in low light and good at sensing motion but don’t sense color. During the day, our cones are busy serving up fall’s palette of colors, while at night the rods help us find our way in darkness.
Cameras are eyes that accumulate light. We see everything instant to instant, where a camera set to time exposure can gather light the way rain fills a bucket. The more light, the more color revealed, hence the reason photos of the Orion Nebula blow us away. Also, the electronic chip that records the picture can be more sensitive to certain kinds of light — especially red — than the human eye, further exaggerated the color effects. Of course, the problem with a photo is that beautiful as it might be, it’s only a facsimile of the real thing. And from our own personal experience we know that the real thing is always better and far more interesting than any copy even though it may lack the glitz and glitter.
OK, how about taking a spaceship to the nebula to see it close up. Would that help? First off, seeing them in a telescope is like going part way in a ship, and we know that adds only a little color in some cases. These objects that fit so nicely in a telescope’s field of view are in reality so vast and diffuse that getting closer would only spread them more apart and dilute what color there is.
To see a star cluster or a nebula through a telescope is to viscerally experience the real stuff. Bright or faint, nothing can beat it.
Aurora update: Looks like Europe got a good aurora show last night. The solar blast arrived earlier than forecast during daylight hours for the U.S. By nightfall, activity was subsiding. Oh, well. Next time.