This past summer, I had the opportunity to spend some time in Bryce Canyon National Park. It is not officially a dark sky park certified by the International Dark-Sky Association, but it’s darn close, especially given its remoteness and elevation. One evening while there, we had an opportunity to look up into the heavens through telescopes provided by the National Park Service and able to see some amazing sights – Jupiter and her four moons, Saturn, Vega, and a few others.
Later in the night, we could begin to see the filmy, cloud-like presence of the Milky Way Galaxy, or rather the other side of it since we are a part of said galaxy. What a tremendous experience.
I’ve always been fascinated by the idea of space, at how much of it is out there, and what it means that it (and we) are there floating around in it.
I’m currently reading the book The End of Night, by Paul Bogard, with a friend of mine and he pointed out a paragraph in the introduction that got me thinking about that which is beyond planet Earth. Astronomer Chet Raymo says:
I have often constructed a model of the Milky Way Galaxy on a classroom floor by pouring a box of salt into a pinwheel pattern. The demonstration is impressive, but the scale is wrong. If a grain of salt were to accurately represent a typical star, then the separate grains should be thousands of feet apart; a numerically and dimensionally precise model of the Galaxy would require 10,000 boxes of salt scattered in a flat circle larger than the cross-section of the Earth.
So the universe is big.
How big? That’s a great question. Let’s get into that, and then wrap up with some implications.
It’s so unfathomably big, it’s impossible for our human minds to conceive the size. We have nothing to compare it to for there is nothing remotely like it in the universe – because it is the universe! If you type ‘universe’ into Wikipedia, it states “The size of the Universe is unknown. It may be infinite.” It also states that the observable Universe is 46 billion light-years (see below what a light year is) in radius. And to stack on top of that, scientists think it’s still expanding, growing ever larger.
How else to describe just how large our universe is? The closest star to our own Sun is Alpha Centauri. It’s just a short 4.24 light years away. How far away is that? According to universetoday.com, NASA’s New Horizon is the fastest spacecraft out there traveling at roughly 60,000 km/h which for all of us American types is 37,282.3 mph. At that speed, New Horizon would reach the three sun cluster that Alpha Centauri is a part of in about 78,000 years.
For even more fun, think about this. We know it takes how many ever light years for the light of whatever star we are looking at to reach us. Not only are we looking at light that has taken quite some time to get to us, but we are also literally looking back in time. Or likewise, if some alien life form out there somewhere were able to look at Earth through an incredibly powerful telescope, when they look at the picture show from our planet, we humans may not even be a part of the story just yet. It could conceivably take millions of years for our light to reach another planet in another galaxy.
And since I’ve brought up galaxies, let’s talk about ours. The Milky Way Galaxy is kind of an out of the way, smaller galaxy. We only have somewhere between 100 and 400 billion stars. Yep, I said billion. That is a number that seems to increase with every new technology we come up with to view the sky. In our galaxy, we also have roughly the same amount to planets as stars. And so if Alpha Centauri is only 4.24 light years away then the far side of our galaxy is really, really far away.
I suppose I should explain light years. Mind you, this is coming from a humanities guy. A ‘light year’ is often mistaken as a unit of time. It really is not. According to the International Astronomical Union, “A light year is the distance that light travels in a vacuum in one Julian year.” Light travels at 670, 616, 629 mph (in a vacuum) so the measured distance, lengthwise, of a light year is about 6 trillion miles. It’s all very confusing actually and again I must thank Wikipedia and universetoday.com for helping me out here. Just don’t think that it takes four years and two months for the light from Alpha Centauri to reach Earth.
So back to galaxies. Astronomers estimate there are at least 500 billion galaxies – at least 500 billion galaxies. That’s not a number we can conceive. Imagine 500 billion coffee mugs. You can’t. You have no basis for comparison. You can imagine the space 10 coffee mugs might fill, and even 100 coffee mugs, but 1000 coffee mugs and your estimate would be wildly off.
When asking how many stars there are, the Royal Museum of Greenwich says there are 70 thousand million million million or 70 sextillion or 7 x 10 to the 22nd power. And if you want to ask how many planets are out there, well, we’re going to have to get into some pretty crazy scientific notation to spell that one out. There’s a bunch of them, okay? Let’s leave it at that.
Of course, this is all highly theoretical. I mean, when you’re throwing around digits in the hundreds of billions, the word really begins to lose its meaning. We don’t entirely know how much is out there and we probably never will. We most certainly won’t ever travel to another solar system unless we can figure out how to bend time which, sadly, also means we probably have never been visited by aliens.
Bill Bryson puts it well in his book A Short History of Nearly Everything when he said
The upshot of all this is that we live in a universe whose age we can’t quite compute, surrounded by stars whose distances we don’t altogether know, filled with matter we can’t identify, operating in conformance with physical laws whose properties we don’t truly understand.
Given the size of the universe and its complexity, it seems a little arrogant that we humans think we’ve got things here on Earth figured out. We have a silly certainty of how things ought to be, even though outside the protective casing of our atmosphere, it seems that well in excess of 99% of the universe is filled with nothing. Exactly what should we do with this fact? What does it mean for us humans on planet Earth?
I do not mean to suggest that our everyday experiences are without significance. Indeed, the most important things in life we can tend to is ourselves, those we love, and the greater good of humanity, which has nothing to do with the physical universe. But perhaps in light of the size of the universe, a little humility might be in order from time to time. Our little human issues really may be just that, little.