The Stars Within an Eyelash's Reach
What brings this on? Well, the skies of Death Valley, actually, which I just returned from (Death Valley, not its skies!) over the holiday break. My daughter and I went down there, mainly to crawl around the sand dunes and canyons, visit sites of the Gold Rush pioneers who gave the valley its [English] name, and get another good, up-close look at the raw Earth….
…but, as always, at night, when the campfire sparks warmly, I end up looking to the stars, which are extraordinarily bright in the dark desert skies. And I just get to thinking…again….
My touchstone on the vastness of the Universe is the knowledge that all the stars we can see in the night sky, with our unaided eyes, are quite starkly the closest things to us in the Universe—and even from those objects, light, traveling at 186,300 miles per second, takes years, decades, even centuries just to reach us. These "local neighborhood" stars are all within our Milky Way galaxy, and all among the very closest of them.
So, the stars of the night sky are a sort of "front drop"—like a big sheet of paper with stars printed on it, held before us–and the stars and galaxies of the rest of the Universe, beyond this "front drop," are too far away for our eyes to perceive their light (without the help of a telescope).
Trying to put the scale into perspective (trying very hard!), if this "sheet of paper" with stars printed on it, held in front of our collective Earthly "face", was, say, 1000 light years away (6000 trillion miles—which is actually about the greatest distance that our unassisted eyes can detect individual stars, and only stars of the most luminous type at that), this would be analogous in scale to an individual person holding a star-printed sheet of paper about two tenths of an inch before their eyes (yeah, I know, too close to focus on the printed stars…), with the surrounding Bay Area representing "the rest of the Universe."
What? I didn’t hear you…. What I said was, if the entire Bay Area represents the Universe, then the stars we can see with our eyes are found within two tenths of an inch of our eyeballs…. Even the Andromeda Galaxy, the most distant object unaided human eyes can perceive (and which I did spot as a very faint smudge on the dark Death Valley sky!), at a distance of about 2.5 million light years, would be less than 4 feet away from you in your Bay-Area-scaled Universe.
It’s here that my mind boggles, and it becomes doubtful to me that our brains have the capacity to really wrap around the Universal scale. It’s hard enough imagining the distances to the "nearby" local stars, a space in which light spends centuries crossing; trying to see beyond that big sheet of paper, to the 13.7 billion light year extent of space and time…boggle…fail….
So, the next time you find yourself gazing at the stars, remember that those are just the spots flittering around in front of our collective eyeball, no more than an eyelash away….
And if that makes you feel small, cheer up; you live in a Universe that is altogether astonishing and magnificent, and not just a run-of-the-mill Universe of comprehendible size. I feel honored and proud….