S1E2 10,000 Boxes of Salt

A few summers ago, 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 is close, especially given its remoteness and elevation.

One evening while there, we had an opportunity to look up into the night sky through telescopes provided by the National Park Service (by the way, big NPS fan). And we saw 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.

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 floating around in it.

I once read the book The End of Night (2013), by Paul Bogard, with a friend of mine and he pointed out a paragraph in the introduction that got me thinking about what 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, in other words, the Universe is big.

How big? That’s a great question.

The Universe is so unfathomably big, it is impossible for human minds to conceive of its size. We have nothing to compare it to because there is nothing else remotely like it; it is the only one we have. 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 is still expanding, growing ever larger.


  • S1E2 10,000 Boxes of Salt
    We occupy an expansive universe whose materials we hardly understand, with distances between stars we can’t really fathom.

How else to describe just how large our Universe is? The closest star to our own Sun is Alpha Centauri. It is 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 traveling at roughly 60,000 km/h, or 37,282.3 mph (for us Americans). At that speed, New Horizon would reach the three-sun cluster that Alpha Centauri is a part of in about 78,000 years.

To confound us even further, think about this. We know it takes about however many light years for the light of whatever star we are looking at to reach us. Apparently, the closest galaxy is the recently discovered Canis Major Dwarf Galaxy—only 25,000 light years away. When we see light from the stars in this galaxy, we are literally looking back in time. And 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 aren’t really a big part of the story just yet.

And since I have brought up galaxies, just briefly, let’s talk about ours. The Milky Way Galaxy is a kind of out-of-the-way, smaller galaxy. We only have somewhere between 100 and 400 billion stars. That number, by the way, seems to increase with every new technology we come up with to view the sky. 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 isn’t. According to the International Astronomical Union, “A light year is the distance that light travels in a vacuum in one Julian year.” So in a way, it’s a measure of time, but also distance. Light travels at 670, 616, 629 mph (in a vacuum) so the measured distance, lengthwise, of a light year is about 6 trillion miles, which is all very confusing, actually. Just don’t think it would take us 4.24 years to get to Alpha Centauri with our current technology.

Okay, back to galaxies. Astronomers estimate there are at least 500 billion galaxies. That’s not a number we can really conceive. Imagine 500 billion bowling pins. You can’t. You have no basis for comparison. You can imagine the space 10 bowling pins might fill, and maybe even 100 bowling pins, but 1000 bowling pins and your estimate would likely be very off. 

When asking how many stars there are, the Royal Museum of Greenwich says there are 70 thousand million million million; however, physicsoftheunverse.com says ten billion trillion, which is 10 to the 22nd power, but could be as many as 10 to the 24th power. And if you want to ask how many planets are out there, well, we’d really have to get into some pretty wild scientific notation to figure that one out. There are a bunch of them. Let’s leave it at that.


Of course, this is all highly theoretical. I mean, when you are throwing around digits in the hundreds of billions, the word really begins to lose its meaning. We do not 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 also means we probably have never been visited by aliens.

Bill Bryson puts it well in his book A Short History of Nearly Everything (2003) when he says: “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 might think we have unlocked the “. . . language in which God has written the Universe.” Galileo said this in the context of mathematics, but even outside of this, we humans 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 99.99999% 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 don’t mean to suggest that our everyday experiences are without significance. Indeed, the most important things in life we can do is tend to ourselves, those we love, and the greater good of humanity, which has nothing to do at all with the nearly incomprehensible size of the 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.

(By the way, a quick update from the previous episode: my former high school does, in fact, now staff a librarian.)

Curiosity Manifold

A podcast where we attempt to notice easily overlooked aspects of human experience.

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