Tom Johnson, creator of the Working Technic Knitting Machine is back with another fun creation: a real, working orrery.

What's an orrery? As any fan of The Dark Crystal knows, it's a device with which to impress gelflings. Tom's orrery exists, "to help explain to my children why we have so much light in the summer and not nearly enough in the winter (we live in Alaska). No attempt was made to get relative sizes, distances, or the orbit periods correct. Rather, this model shows the inclination of the earth's axis and why it causes the seasons."

Lego Orrery [Mac]