Our local star (Sun, Sol, etc.) is pretty big, right? To say the least! Consider that 1.3 million Earths could easily fit inside our Sun, and you've got quite the planetary party right there! So, what if we wanted to scale this somehow; kind of put it into perspective with the rest of our galaxy? I know, let's make a scale model of the Milky Way!
Okay, first, let's start with some numbers 'cause numbers are just plain cool, and they allow you to, well... count things! Our Milky Way galaxy contains somewhere between 200 and 400 BILLION stars. To make this easy, we'll use a number somewhere in the middle, say 300 billion stars, fair enough?
If we're going to make a scale model of our galaxy, and there are 300 billion stars in said galaxy, we can't go using something like basketballs as the models for all those stars. First, we wouldn't have enough room to paste all those basketballs to our model, and second, Spalding (TM) could never in their wildest dreams produce that many basketballs for our model anyway. So, let's use something a little more manageable: salt. We'll assume each star in our model is the size of a grain of salt. Not only is it easier to comprehend things at this scale, but it also makes for a really delicious steak. Just toss a pinch of stars on a rib eye and mmm, mmm, mmm, mmm, mmmmmmmmmm!
Now that we have our scale down, let's gather our ingredients. Let us consider a typical 26oz box of Morton's table salt that you can buy at any grocery store. You know, the blue cylinder-shaped package with a girl out in the pouring rain spilling salt all over the place (She seems rather clumsy and oblivious to what's going on if you ask me. What kind of marketing campaign is that, anyway?). On average, because I don't want to speak in absolutes and risk being sued if my count is off by a few grains, there are about 16.25 million grains of salt in a typical 26oz package. To account for all the stars in our Milky Way, we would have to purchase approximately 18,462 boxes of salt, give or take a few. Now, I know what you're thinking: how many shopping carts am I going to need at the grocery store, and do I have any coupons? Well, forget the boxes. Those are too cumbersome. Let's think bigger, say... bathtubs! Okay, one bathtub filled with Morton's table salt will hold about 1 billion grains of salt. So, we're only going to need 300 bathtubs to hold all our "stars" (waaaaay easier than thousands of little boxes).
Alright, with our warehouse packed with 300 bathtubs filled with salty stars, let's consider other supplies needed for our scale model, namely construction paper. All our crafts and projects used construction paper when we were kids, right? Same here. And since space is dark and salt is white, we're going to use navy blue construction paper to help our salt/stars stand out. But how much paper are we going to need to really scale this puppy out? Lots! And I mean LOTS, with a capital... well, all of those letters! Let's just get started and see how much we end up needing, shall we?
Our Milky Way is currently thought to be a barred spiral galaxy, which means it has a central bar packed with a whole mess of stars with a couple of arms spiraling off the ends of the bar. So, right off the bat, we'll need to grab our safety scissors and cut our construction paper into a nice pretty circle (quit asking how big, we'll get to that). With that out of the way, let's start gluing some salt!
To properly represent the scale of our Milky Way and all the stars it contains, we have to be very careful how and where we glue the salt to our paper. First, no two grains of salt can be any closer than seven miles to each other. That's right, SEVEN MILES! Stand in the very center of your ginormous piece of construction paper (Again, stop asking exactly how big. It's ginormous. That's all you need to know right now!). Grab your Elmer's paste (the original mint-flavored kind will suffice), stoop down and glue a single grain of salt right in the center. Now, lace up your running shoes, sprint seven miles in one direction (nearly a quarter marathon), and glue another grain of salt. Glue, run, paste and repeat another 298 billion times!
Okay, now that you're done gluing all your salt grains to your ridiculously large piece of construction paper (I know, I know, we're getting to that), sit down, slip on a pair of fluffy bunny slippers, have a bottle or two of Gatorade, and relax a bit. Next, I just gotta know, how much of the Elmer's paste actually made it to the paper and how much did you ingest? Tasty, isn't it?!
Right, so, we have this scale model of our Milky Way galaxy made out of salt, paste and construction paper. It's a good thing we decided to scale the stars down to the size of salt grains, right?! Otherwise this model would be unmanageably humongous! Just how big is it??? Glad you asked! If we really built this thing out of salt and properly scaled it to the correct proportions, our giant circle of construction paper should easily fit within the orbit of Mercury.
Yep, Mercury! Not the size of the planet itself, but the area encompassed by its orbit around the Sun. You know, that tiny little grain of salt at the center of our solar system.