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# How Big Is the Solar System?

How big are the planets of the Solar System compared to the enormous Sun at its center? How far would you have to travel to reach each of them? And how can you build your own scale model of the Solar System to see all of these relative sizes for yourself? Keep reading to find out!

By
Jason Marshall, PhD
Episode #205

So that's where Mercury goes, but how about the other terrestrial planets? Take another step or two to the 2 yard line, and that's where Venus goes. A few more steps brings you to Earth's position about 6 inches short of the 3 yard line. And finally, a little less than mid-way between the 4 and 5 yard line is where Mars orbits the Sun.

How big are these planets? Not much bigger than Mercury in comparison to the Sun. The diameter of Mars would be a little more than the thickness of a US dollar bill in our model, and the diameters of Venus and Earth would be about the same as the thickness of two US dollar bills.

## Where Are the Giant Planets?

Now, things start to get interesting. As we've seen, the inner terrestrial planets are all located relatively close to the Sun—after all, we haven't even made it to the 5 yard line. But the outer giant planets are much more spaced out (no pun intended.)

The giant planets orbit far, far away from the Sun

To get to Jupiter, we have to take a little walk to just shy of the 15 yard line. To get to Saturn, we need to walk to the 27 yard line. And then it's time to really start walking, because to get to Uranus, we need to walk to around the 45 yard line on the other side of the half way line. And Neptune? Amazingly, you have to walk all the way to about the 15 yard line on the opposite side of the field from the Sun. As you can see, the giant planets orbit far, far away from the Sun—and their orbits are, comparatively, very widely separated.

In our model, the diameter of Jupiter is a little less than the thickness of two US dimes stacked on top of each other. Saturn's diameter is a little smaller—about the thickness of a US nickel. And Uranus and Neptune's diameters are a little less than the width of a US dime.

Compared to the diameters of the terrestrial planets (which were all measured in terms of the thickness of a US dollar bill), these sizes are huge—that's why they're called "giant" planets. But compared to the size of the Sun—whose diameter, remember, is equal to the diameter (not the thickness) of a US quarter—even these giant planets are tiny.

## Wrap Up

OK, that's all the math (and Solar System astronomy) that we have time for today.

Please be sure to check out my book The Math Dude’s Quick and Dirty Guide to Algebra. And remember to become a fan of the Math Dude on Facebook where you’ll find lots of great math posted throughout the week. If you’re on Twitter, please follow me there, too.

Until next time, this is Jason Marshall with The Math Dude’s Quick and Dirty Tips to Make Math Easier. Thanks for reading, math fans!

Solar System and football field images courtesy of Shutterstock.