Correcting for the Cataracts of the Night Sky

Have you ever walked under the vault of a star-filled sky and felt your breath taken away in wonder? Seen the river of the Milky Way flow across the pasture of your night field and wondered at its course and speed – at where it had been and where it was going? Noted the colors of the stars and nebulae and imagined what it must be like to look out at their skies and see (or not see) the universe from their perspective?

One of the most amazing images from astronomy is that of the “Pillars of Creation” from the Eagle Nebula (M16). From 7000 light years away, we have a wonderful view of this incredible emission nebula and the 9.5-lightyear tower of gas and dust that juts out from the rest of its mass like a monster’s hand reaching out. It actually extends over 90 trillion kilometers (56 trillion miles).

This distant sky object is pretty impressive from here, but try to envision what it would look like as you got closer and closer to it. How it would begin to lose detail and become more diffuse as you approached one of the stars embedded in its gas and dust. This is a star-forming area, so perhaps there are no planets yet, and even if there were, likely no life yet. But for the sake of this thought experiment, let’s assume there are both.

What would someone living on one of those planets orbiting one of those stars see on a starry night? Could they see through the cataracts of a clouded envelope of space?

Cone Nebula/NGC 2264 Photo: ESA/Hubble under Creative Commons Attribution 3.0 Unported License.

Cone Nebula/NGC 2264
Photo: ESA/Hubble under Creative Commons Attribution 3.0 Unported License.

Would they see a cloudy, dusty night devoid of light? Or a mirky sky save a few stars? Or perhaps a bevy of local stars, but not much beyond the pillars themselves? Or, perhaps there would be great, ghostly towers with winking eyes brooding down like angry gods surrounded by wisps of angels wings doing battle for their souls. Imagine the children’s dreams built around that mythology!

Would the gas and dust be gray or colored by the light of active stars of different sizes and temperatures – blue giants or red dwarfs or yellow guardians like the Sun? Would the stars be colors or hidden in sheer curtain swaths of gas or dark grainy dust? How close would the stars be?

Our night skies are relatively clear so we see a star-filled sky on a dark night. The photos we see of nebulae involve long time exposures using different light filters, so those images aren’t what we see when we look at the objects live through a telescope lens. We usually see a limited exposure to light and sometimes not a very colorful view. Someone at one of these nebulae likely would see something equally limited, plus they wouldn’t have the advantage of sight-at-a-distance.

Think of how different a cloud looks if you’re inside it from how it looks from miles away. A distant towering cumulus cloud looks like a building tower of cottage cheese, but flying through the edge of one is like flying through the edges of a foggy field. You can probably imagine that the Pillars of Creation would be very similar – except millions of times higher and wider and less dense. They look heavy and dense to us because we are so far away.

I often think of this as I gaze up at the night sky and see the plane of the Milky Way drift out across the sky. Billions of stars within the grasp of my eyesight. Plus billions of planets I cannot even see. Beyond the Milky Way, our nearest satellite galaxies (like the Magellans) and then Andromeda, our nearest larger neighbor galaxy. Stretching even further out, beyond my ability to glimpse, are billions more galaxies all the way to the edge of time. I’ve seen them in photos, some so distant they are hardly larger than the pixels of the cameras that captured them, smudges yet with light signatures that betray them. All this we can see with the aid of glass perfected into lenses and a relatively unobstructed view.

We are sometimes challenged with the question, “If there are aliens ‘out there,’ why haven’t we heard from them?” Perhaps one answer is that alien vision is clouded by the cataracts of their night skies and we are the seekers with the clearer vision. Perhaps it’s up to us to seek first.

 

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