Skies to Stars: How Big is Big?

By Ed Downs

Even with a modest amateur telescope, one can see unimaginable distances and travel through nearly endless time. Distance numbers that are simply difficult to picture in a visual manner sometimes challenges even the pros. Units of measurement, like miles, kilometers, lunar units, astronomical units, light years, parsecs, kilo parsecs and many more are used to describe the vastness of our universe with modest success.  Spacecraft have now reached planets as close as Mars, and as far away as Pluto, but what is the real relative distance being traveled to visit our closest planetary neighbors?  Most classroom models of our tiny solar system show the planets as being equally spaced as they circle the sun. The fact is, if made to scale, some classroom models would take up several city blocks.

This writer was recently gifted a terrific book, The Total Skywatcher’s Manual, authored by Linda Shore and David Prosper, both representing the Astronomical Society of the Pacific. This is an absolutely “must have” book for any individual who wants to know more about all things astronomical, written in a fun and entertaining manner and filled with incredible illustrations. It is divided into multiple, short chapters of information, with “Chapter 110” teaching one how to construct a proportionally correct model of our solar system. This is a real revelation and great fun for both adults and kids. Follow along as The Total Skywatcher’s Manual gives you a perspective that is jaw dropping. 

First, buy some adding machine tape (have anyone under 20 years old Google, “adding machine” to learn what it is), and yes, you can buy adding machine tape at Walmart.  Cut off a four-foot piece and follow along.

Step one: Write (small print) “Sun” at one end of the tape and write “Pluto/Kuiper Belt” at the other end. You have now defined the extreme ends of our solar system.

Step 2: Fold the tape in half and give it a good crease. Open the tape up again and write “Uranus” on the crease.

Step 3: Re-fold the tape along the “Uranus” crease. Now, fold it in half again, with a good, sharp crease. Open the tape up and note that you have now divided the tape into quarters. On the new crease closest to Pluto/Kuiper Belt, write “Neptune.” On the new crease closest to the Sun, write “Saturn.”

Step 4: Make sure the tape is now open. All of the rest of the planets are now going to fit between Saturn and the Sun. Take the “Sun” end of the tape and fold it up to the “Saturn” crease, and make a new crease. Open the tape up and write “Jupiter” on the new crease.

Step 5: Starting with the tape open, once again take the “Sun” end of the tape and fold it up to the new “Jupiter” that you just wrote on the tape, and make a crease. Open the tape up and write “Asteroid Belt” on the new crease. 

Step 6: Once again, starting with the tape open, fold the “Sun” end of the tape up to the “Asteroid Belt” crease that you just marked, and make yet another crease. Mark this new crease “Mars.”

Step 7: Now, this one gets a bit complicated, so go slow. You will be making some creases that are surprisingly close together, kind of like origami. Starting with the tape open, fold the “Sun” up to “Mars,” and crease. Do not open the tape this time, leave it folded to Mars. Now, take the folded end that you are working with up to “Mars” again.  Yes, these are very small “folds”, so be careful. Open the tape up, and you will now see three unlabeled creases between Mars and the Sun. 

Step 8: Label the crease closest to the sun “Mercury.” Label the crease second from the Sun “Venus.” Finally, label the one remaining crease; you guessed it, “Earth.”

So there you have it, a reasonably correct model of our solar system in the correct proportions. There are a couple of interesting takeaways from this exercise. Earth, Venus, and Mars reside in what is called our “Goldilocks Zone,” where, given fortuitous conditions, life, as we would understand it, could exist. Given our recent ability to see planets circling other stars, this is the region to which we are giving special attention as we discover thousands of confirmed planets and billons of yet-to-be-discovered planets. Most amazing is the realization of just how far the New Horizons spacecraft had to travel to take photos of Pluto. Moreover, remember, the Voyager spacecraft have sailed past the Kuiper belt, reaching interstellar space. Pretty cool stuff. 

Visit www.astrosociety.org for more information about the remarkable book, The Total Skywatcher’s Manual and the Astronomical Society of the Pacific. This is a terrific organization, dedicated to the education and enjoyment of astronomy. It is a great place to extend your earthbound flying into the universe.