Branko is back to check out another Technic Set: this time its an Orrery – 42179 Planet Earth and Moon in Orbit

My expectations for this set were very high; I have a fascination with space and I love an orrery (that is essentially what this set is) as a way of illustrating movements of our planet. This set allows you to explain several of the main impacts of the solar system on life on our planet, but it falls flat on one important point.

This 526 piece solar system containing a sun a moon and a the real estate of a whole planet, will set you back $AUD99.99/£69.99/$USD74.99/€79.99 which, considering current real estate prices in Australia, is not a bad deal!

Read on to find out why you should absolutely get this set to learn or teach about seasons while also having a neat display model, but also what my concern is with one aspect of the set.

Should you buy yourself a solar system?

Yes, yes you should buy yourself this solar system. I’ll get right to the bottom line: this set is great. The accuracy of the movement of the moon and ‘Earth’ is pretty good and it demonstrates nicely the changing of the seasons and moon phases. The mechanisms moves surprisingly smoothly and it’s very satisfying to just sit there winding the crank and see the orbs fly around.

The printing or ‘Earth’ is not quite right to represent our planet, but if that doesn’t bother you this is a unique LEGO set that fits well as a display model or a conversation piece on a coffee table.

The finished solar system

The finished model of the solar system looks unusual. The details of the set (the sun, planet and moon) are actually the most boring aspect of the model while at the same time being the lead performers. The build is a bit sparse between the balls (although not as sparse as the real solar system) but this doesn’t matter because it won’t take long until you’ll want to start making things move.

As soon as a you get your hands on this set you will find the crank and start turning it, observing the smooth movement and the dials indicating what you are looking at. The elegance of the gearing system inside the contraption is mostly ignored although it *is* mostly visible, which is a testament to the execution of the subject matter.

It is great that LEGO decided to include such an educational an fun set in the series of space themed sets this year, which really tickles my excitement of real space exploration, and all the things we know and do not yet know about the great environment we live in.

The functionality of this set (the movement) is the main attraction, so let’s explore them one by one. The single rotating orb in this model is a nice simplification, of the complex rotations of our real sun. It’s nice that it is included to remind us that the sun is not a stationary non-moving object.

It is also possible to see a solar ecplise or lunar eclipse but only by positioning a camera just right on the earth (much like in reality)

Changing of the seasons

Underneath the sun is a reddish-orange ring (a colour that still creates excitement at the Rambling Brick HQ) with stickers indicating the names of the months. As the planet moves around the sun the pointer indicates what month it is, and a full rotation represents, you’ve guessed it, a full year.

There is a clever mechanism in the arm holding ‘Earth’ that keeps the base of Earth in the same position as it turns around the sun. Because Earth is also on an angle (as it really is) the position of the Earth around the sun defines the astronomical seasons. Note that some countries use slightly different dates to define the seasons, but the sun and Earth are not bothered by such details.

At the start of the year the Southern Hemisphere is pointing mostly at the sun (summer in the south) which so the Northern Hemisphere sees less sun and experiences winter (Dec-Feb).

In March and September the ‘side’ of Earth is facing the sun which means that the sun faces exactly the equator and both the north and south get the same amount of sunlight. This corresponds to the equinoxes, or the autumn/fall and spring (depending on the hemisphere).

Around the middle of the year Earth is on the other side so Northern Hemisphere is facing the sun more than the south; meaning it is summer in the north (July-Aug) and winter in the south.

With a laser pointer it was possible to illustrate that this model accurately shows the position of Earth with respect to the sun at different times of the year, which allows you to see what the season at any point on Earth is by looking at this model! (note: please read the ‘problem with the planet’ section about this)

Moon phases

Around the bottom of Earth is a dark grey ring with stickers indicating the moon phases which is very welcome because it requires a bit of imagination (or a flashlight and a close eye) to imagine these phases. The changing shape of the moon is caused by the son only shining on one side of the moon, and we can only see the moon from another side.

When the moon is full it means that we are on the same side of the moon as the sun so we can see the entire side of the moon that is being lit. When the moon is half-full we are next to the moon (with respect to the sun) so when we look at the moon we see one side that is being lit by the sun, and another that is dark.

When the moon is entirely dark (new moon) it means the moon is between us and the sun and we cannot see any of the sun shining on the moon because we are on the wrong side.

Ironically, the side of the moon we cannot see is typically called ‘the far side of the moon’ or ‘the dark side of the moon‘ although, as you just saw’ the ‘dark side’ can actually be completely lit by the sun, it just means it is the side we cannot see from Earth.

Another thing we notice when the model moves is that the Earth rotates around its own axis. Each rotation corresponds to one day, and the moon rotates around the Earth. Using the highly scientific method of ‘rough-estimate-via-eyeballing-it’ we could see that each lunar rotation takes about 26 days (it should be about 29) and the year is not quite 364 days, but pretty close. The model does show that a lunar month (the word ‘month’ comes from moon) is not quite the same as a calendar month, which is again accurate and a nice conversation starter.

The problem with the planet – it is wrong

Eagle eyed readers will have noticed there is something odd about Earth in this set; the shapes of the continents do not match our home planets, not even by approximation.

Maps of the world always show some kind of deformation because they try to show the surface of a globe onto a flat map. The Mercator projection map was originally designed to assist navigation because the directions of travel with relation to a compass were accurately given from the map, even if distances and areas near the poles were exaggerated. When actually putting a map on a globe (like in this set) this is not an issue, everything can be represented in the proper shape and location.

For reference look at the map provided on worldmapwithcountries.net showing the location of the equator (the middle of the planet) and the tropics (the highest and lowest points of the laser pointer in the videos above).

When drawing the equator from this map onto the globe you can se that LEGO decided to place the equator nearly 2/3 of the way down the globe. This means that significant parts of Africa and central and South America have been migrated to the Southern Hemisphere! This means that you should be careful when teaching about seasons in those regions of the world; don’t use this to explain seasons to someone in Mexico or India!

It baffles me that LEGO would get something so basic so wrong. It isn’t that difficult to find a globe map and even when enlarging specific countries (I can imagine they want to emphasize Denmark a bit), in this set the countries should at least be in their correct hemispheres. They could have even looked at their own set 21332 the Globe which correctly places the continents! I hope that LEGO will issue a correction for the globe; I strongly encourage you to contact them and ask for it. You deserve to get an accurate picture! (yes. that is a pun.)

If this ball annoys you it is off course possible to replace it with a brick-built alternatives from instructions generously provided by JKBrickworks (the designer of the pop-up book). https://jkbrickworks.com/earth-moon-and-sun-orrery/

The weight of such a brick-built planet does make the mechanism struggle a bit to get moving.

Building the world

If you are still with us after all that, lets look back and the build process. In the box is a densely packed set of paper boxes. You can see that the stack of LEGO almost keeps the shape of the box after removing it; this is a full box!

There are a few loose pieces and some plastic bags with some larger parts. The large flame yellowish orange ball (sun) and the blue ball pieces with printing (Earth) stand out from this.

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Opening the first bag (with some extra pieces) presents us with a nice stack of Technic pieces with 4 black round gear pieces that excite me (I like big wheels and I cannot lie) and the ring in reddish-orange. I love how Technic is adopting more and more colours in their sets.

After finishing the first section, the foundation is set, showing a sturdy beginning and something that looks like a clockwork.

The next bag shows a few regular bricks and a nice range of gears with different sizes, which is the main theme of this build: gears running at different rates.

The build proceeds with some gearing and anther reddish-orange ring containing the season stickers

For the next step we see the arrival of the sun. This part appears to be new and it also comes with nice yellow pins to match the colour! Putting these parts into the build gives a stand for the sun and an arm reaching outwards. I forgot to take a photo with the sun fully operational.

The next section brings us Earth and moon so we can expect to be building that planetary system.

Inside the grey support wheels, guidance wheels for Earth is created using ball pins inside pins that fits very well and looks quite elegant. Stickers on the outside of the wheel indicate the moon phases. I like how they added the black line on the sticker to ensure they are placed correctly, while also added a little stylish flair.

The final step is to mount the planet on the sun so they can start their orbit!

Overall Conclusion

If you’ve reached this stage of the page you much realize that I like this set (a lot!). The subject appeals to me, the way the gearing is executed is very good, it runs smooth and the build just asks to be turned. I think anyone with a passing interest in our world would enjoy having a quick play with this set, and I think many people will enjoy having this on display. Someone interested in Technic will enjoy the intricate gearing in this set with a great reference how to do it well! (I can provide some references how to do it very poorly on request). Many people will be tempted to give the little crank a turn and this model almost sells itself at that point!

That being said; I cannot on good conscience give this set more than 4 out of 5 arbitrary praise units, just because of the printing of our Earth. In this particular set I think it is very important to be precise and show care for reality because this set has such strong potential for education. I really hope against hope that LEGO will release a fix/update for the globe.

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Until Next Time,

Play Well!