Here is project #2 with the new 3D printer, just like the Berlin Wall it’s an artsy one: the eight planets of our Solar System scaled down by a factor of about 109. This post contains a photo gallery of the planets, and further down the details of design, creation, and painting.
Photo Gallery
The eight planets from left to right: Mercury, Venus, Earth (that’s us on that small half-sphere!), Mars, Jupiter, Saturn, Uranus, and Neptune.The planets installed on the wall. Note that the distances are also to scale, however, if planet sizes and distances were supposed to match, the planets would either need to be scaled down by a factor of one thousand or the wall in my apartment would need to be around 4.5 km long. In short: It is merely impossible to model the Solar System with both distances and object size at the same proportions. For this miniature I am using a scaling factor of ×10-12 for the distances and ×10-9 for the object sizes. On another note I find particularly cute how the small planets Mercury, Venus, Earth, and Mars are cluttered closely together on the left-hand side.A close-up of the small planets (Mercury, Venus, Earth, and Mars). On our planet the continents North and South America can be seen.Jupiter: Miniature and original next to each other. The diameters are 14.6 cm and 140,000 km respectively.The beauty Saturn posed a special challenge with its rings. Here the model is juxtaposed to the real planet in side and bottom-up view.Lastly, the two outer-most planets Uranus and Neptune.
Details of the Creation Process
Scaling and Planning
This project started off with the idea of creating a to-scale version of the Solar System where both object size and object distances are at the same scale. Naively I assume that would be possible, so I created a spreadsheet and did the math on it. Turned out it was not possible at all, so two different scaling factors needed to be found: one for the planet size and one for their distances from the Sun.
The wall in my apartment is about 4.5 m long so the distance of the furthest planet, Neptune, had to be scaled down from 4,530,000,000,000 km to 4.5 m. The object diameters were constrained by the 3D printer’s print bed and my personal preference so I defined the miniature version of Jupiter to be around 15 cm in diameter. That resulted in Mercury (the smallest) to be 5 mm large which was not too small to print.
I decided against including moons into the artwork because they fit neither into the solar-system scale (Earth’s moon would stick on the Earth half sphere) nor into the object-size scale (the Moon would be far beyond Mars). Likewise, the Sun is problematic to add because it is enormously large in comparison to the other objects. Besides being hard to paint, it would be almost 1.5 m in diameter when printed to-scale.
Below is a table of the planet sizes and distances:
Distance from Sun [M km]
Diameter [k km]
Distance from Miniature Sun [m]
Diameter in Miniature [mm]
Sun
1392
1450.00
Mercury
57
4.8
0.050
5.00
Venus
108
12.2
0.095
12.71
Eartd
149
12.8
0.131
13.33
Mars
228
6.8
0.201
7.08
Jupiter
780
140
0.689
145.83
Saturn
1437
116
1.269
120.83
Uranus
2871
50
2.535
52.08
Neptune
4530
48
4
50.00
Modeling and Printing of the Half Spheres
The modeling of the 3D objects was fairly straightforward. I created half spheres in Blender and used the slicer software Cura to convert them into a format that the 3D printer can work with. The specific printer is a Ender 3 Pro and the filament is PLA. All prints were smoothed using sand paper with grit 60 and 180 to hide the bumpy seams of the layer-wise printing.
The reasoning behind half spheres is that I reckoned they would look nice when attached to a wall. On top of that they are easier to position than full spheres which would probably require some string attachment or something comparable. Also, half spheres use less material and can be painted faster.
I printed the smaller planets as filled half spheres in one run.For the larger planets I used very little infill (5 to 10%) to save PLA and disabled the bottom layer. The latter made it easier to attach the half-spheres to the wall. The photos shows Jupiter “in progress” on the print bed with Earth and Mars right below.
Painting
While being by far the most time-consuming sub-task, there is little to report about the painting. After sanding, the it starts with two layers of white primer.
Then acrylic colors need to be mixed to best match the color tone of the respective planet. This was a rather difficult task and (as can be seen above) for some planets the color tone does not match particularly well. I used almost exclusively matt colors with few exceptions e.g. for Earth’s oceans.
The last layer of paint is a varnish. While I didn’t take the exact time I’d estimate the paint job to have consumed about 10 man hours in total.
I also want to give a shout-out to a friend who helped me significantly with the painting and color mixing! Jupiter and Saturn we worked on jointly and the other planets half-half.
Here Saturn’s rings are drying. The traffic cone indicates that one must not touch the object at this point. ;-)
Saturn’s Rings
Saturn’s rings posed a special challenge: They are supposed to be as thin as possible (the real rings are estimated to be around 10 m thick – so forget about a to-scale miniature here) and still needed to have the structural integrity to look stiff when attached to the wall.
I first experimented with a version that had a wall attachment (here seen on the left) and was other than that just two layers of print. The thickness was around 0.3 mm. It turned out to be too weak to lift its own weight and hung down too much.Version two was equipped with the same wall attachment and an additional structural support element. It was sufficient for the ring to remain flat when attached to a wall.The reason the screenshots both show quarter rings (rather than half rings) is because a half ring of the correct size simply did not fit onto the Ender 3 Pro’s print bed. I just glued two halves together.An interesting aspect of Saturn’s rings are also the gaps. There are two main gaps, called Cassini Division and Encke Division. The Cassini Division can be seen in the model (it’s the large gap between B ring and A ring) while the Encke Division was too small to model. I therefore drew the Encke Division onto the ring after painting the general colors onto it.
Closing Remarks
I first marked all planet positions on the wall and then glued the small ones on there. For the larger ones I used double-sided adhesive tape. The project was a lot of fun. I am also happy to have a nice decoration which is not too aggressive and yet filling an entire, large piece of white wall.
I honestly find the beauty of our Solar System really touching. While there is no objective definition of beauty, humans still share similar opinions on basic things like flowers, fire, or the sky being beautiful, perhaps simply because it is in our genes. For the Solar System this argument cannot be made, as we have only recently acquired high-resolution images of the objects out there. It is a little bit of an underappreciated circumstance that our seven other planets are not just gray dusty rocks, but such marvelous and diverse objects.
