LEGO Technic Planet Earth and Moon in Orbit (42179)

Turn the crank on this LEGO Technic set and a geared Earth swings around the Sun while the Moon circles the Earth, all driven by the same handle. It’s an orrery, the old clockwork model of the solar system, rebuilt in Technic beams and gears.

The 526-piece set includes printed months and moon phases, so you can see where the Earth sits in its orbit and why the seasons change. Finished, it stands over 9 inches high, 12.5 inches long and 7 inches wide, a good size for a desk or a shelf next to the monitor. Instructions run through the LEGO Builder app, where you can zoom in and rotate each step in 3D, handy for spotting which way a gear is supposed to face.

It’s a natural fit for engineers who grew up on Technic and miss the gearboxes, and for anyone who likes a model that teaches something when you play with it. It also works as a shared build with a kid, since LEGO aims it at ages 10 and up.

The catch: 526 pieces is a modest count next to the big adult Technic sets, so an experienced builder will finish in an evening. Think of it as a desk piece with a crank, not a weekend project.