You recall that we discussed the recent brouhaha over the definition of 'planet', and how it affects the planetary status of Pluto. Well, the current (October) Smithsonian magazine has an article about planets that circle other stars. The article had two words I'd not heard before.

... the team has found about two-thirds of the 200 or so planets discovered outside our solar system so far. ... Some of the newfound extrasolar planets, or exoplanets as they are called, are giant worlds the size of Jupiter that circle their stars on tight, roasting orbits, far closer than Mercury's orbit around the sun.

Marcy reaches behind his neat desk and takes out an orrery, a mechanical model of our solar system. Metal balls at the ends of spindly arms swivel around the sun.

The first one looks like a newish coinage. Orrery is quite an old word that I was already familiar with. The things have been around for a long time.

Orrery is one of my favorite words (I recently integrated a software orrery into a satellite simulation). It was named after the 4th Earl of Orrery, who commissioned one in the 18th century, but such a thing may go back to the ancient Greeks: some think that the Antikythera device was an orrery. John Walker's website has links to software orreries that run in your browser or as a screensaver.