I have the hardest time remembering the number of stars in our home galaxy, the Milky Way. Is it 300 million or 300 billion? Either number is so far out of my ken, so far beyond my ability to grasp, that it won't stick in my head. Moreover, it doesn't seem to make much of a difference. But now I've checked once again -- and it's 300 billion stars (ballpark -- not an exact door-to-door census). That's three thousand millions of stars. Also, it's 130,000 light years from one side of the galaxy across to the center (the radius). The mass of our galaxy is 1.5 trillion solar masses. Does that figure include or exclude Dark Matter? I don't know.
That's just the start. The full story is even more astonishing still. In addition to the Milky Way, there are approximately 34 billion galaxies such as ours in the universe. Or there used to be until a few years ago; the most recent estimate is 100 billion galaxies. From my standpoint, here on what Shakespeare naively called "the sure and firm-set Earth" -- a smallish planet revolving around the lucky old sun in one of the spiral arms of the Milky Way -- whether there are 34 billion or 100 billion galaxies out there doesn't much change the situation. In a nutshell: it's big; we're little.
Even seventy years ago, when I was a boy just starting to learn about the stars, the universe was smaller and simpler. No one told me, because no one knew, about the Big Bang, about star formation, about black holes and supermassive black holes, standard candles, quasars, exoplanets, etc. Knowledge is expanding as rapidly as the universe; it's only a few centuries ago that Galileo was sent to his room for proving that Earth wasn't a still point at the center of the world. "Eppure, si muove."
Actually, I'm glad that Copernicus and Galileo and Newton de-centered the universe. I rather prefer being insignificant. Standing at the center of the universe -- well, it was too much responsibility, too much pressure. It's mighty consoling to be trivial. It helps to put our daily woes in perspective.
Is it more staggering that the universe is so ridiculously immense or that members of our species have had the smarts to figure it out. Not only the engineering skills to devise telescopes and spacecrafts to gather the data, but the brains to think abstractly and mathematically. And the courage to do so. We're an accomplished and admirable species when we're not torturing and killing each other for no particular reason. I'm proud of us, some of the time.
When my father was the age I am now, he said to me, "As far as I can figure, I'm just a link in a long chain going from nowhere to nowhere." He was exactly on target. But we should also remember that the chain of which he spoke includes Bach and Rembrandt and Einstein. And you and me And as long as I remain a link in that chain, I intend to make the most of my insignificant existence -- the only one I have.
"That which we are, we are."
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