Jeff's Lunchbreak

Space is big. I've written about it before, but that was about distant galaxies. But even when you look in what's supposed to be our own 'neighborhood', the solar system, the distances involved are staggering. I don't think most people have a sense of scale of the solar system, such as how big the Sun is compared to the Earth, or how far it is between the planets. So, I did what any nerd with access to a 3D drafting program would do - I modeled it. And once I had it modeled, I figured other people might find it interesting, so I'm sharing it.

To explain the model a bit, I went to Wikipedia and looked up the diameters of each of the planets (all 8 of them - sorry Kuiper Belt objects), and their distances from the Sun. I averaged out their distances so that I could draw the orbits as circles instead of ellipses - not perfectly accurate, but it still gives a good idea of the sense of scale. I put all that into a spreadsheet, and then divided everything by 1,000,000, to get it in sizes that would work in Solidworks. And keep in mind that Solidworks deals in inches by default. So for example, instead of drawing the Sun at 864,900 miles in diameter, I drew it at 0.8649 inches in diameter. The Earth, instead of being 92,956,050 miles from the Sun, was drawn at 92.956 inches from the Sun. And the biggest distance, Neptune's distance from the sun, instead of being 2,798,310,157 miles from the sun, was drawn at 2798.31 inches from the Sun.

Actually, just stop and think about those numbers. If the Sun was less than an inch in diameter, the Earth would be almost 8 ft away (the standard height from floor to ceiling) and only .008" in diameter, while the most distant planet, Neptune, would be 233 ft away (23 stories).

Anyway, here's the model, in two different formats, along with that Excel file that I mentioned.

• Solidworks Model - Solar System.SLDPRT
• E-Assembly Model - Solar System.EPRT
• Excel File - Solar System Scaled Sizes.xls

That first format is Solidworks. It's the better of the two 3D formats, but you need the right software to view it, and Solidworks isn't cheap (a couple thousand dollars a license - so not really for home use). The second format is an eDrawing. There's a free viewer that you can download. The third file is the Excel file. It has a few more ways of scaling that just what I discussed above, which should be pretty obvious from the text.

Here are a few images taken from the model. Each image has been scaled to fit on the blog. If you click on it, you'll get the full size version.

This first picture is the Sun and all of the planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. It's tough to see the inner planets (Mercury through Mars) because they're so tiny. They look like little more than a smudge in the image below, but they're a bit easier to make out if you click on the full size version. The vertical line just to the left of the terrestrial planets is the center of the Sun. In the model, all of the planets are aligned. The image below was made by first looking straight down all of the planets, then rotating the model just 0.04º so that you could see each planet without it being obstructed by any other planet. Another way to think of this is that it shows the planet sizes to scale, and shows the distances properly relative to one another.

This next one is the same view as above, except zoomed in on the terrestrial planets. Again, the tick mark on the left shows the center of the Sun. You can see the Moon in front of the Earth (our Moon is the only moon I modeled).

The next three images are a kind of series. They're looking 'down' at the solar system from outside the ecliptic plane. To me, these really gets across sense of distance. The first is zoomed in to just the Sun and Mercury's orbit. The second one zooms out a bit to show the orbits of all the terrestrial planets. The third zooms out to show the orbits of all the 8 planets.

So first, here's the Sun and Mercury. Mercury's so small that it gets lost in the curve showing its orbit.

Next, here's the Sun and the terrestrial planets. You can still make out the Sun as a sphere and not just a point. The little tick mark at the Earth is because Solidworks shows tick marks at the center of all circles, and I drew a circle there to show the orbit of the Moon around the Earth. But even that orbit's too small to see at this scale.

Third, here's the Sun and all the planets. Zoomed this far out, even the Sun becomes just a point. You can really see just how far away the outer planets really are.

And finally, here's our own backyard - the Earth and the Moon. It kind of gives a sense of scale of just how far the Appollo astronauts went.

To me, this does help to put into perspective just how big the Solar System is. When you look at the farthest humans have ever traveled - to the Moon and back - and then see how even that distance gets lost in the immensity of the Solar System, it makes you feel tiny. And then when you consider the vast distances between stars and across galaxies - I just can't even wrap my head around it.

Anyway, have fun playing with the model.