Sun, Moon and Planets

I love detailed machined engineering parts.  All around us are machines, hidden within which are some beautifully made pieces of metal, plastic, ceramic, detailed 3D sculptures that move together or enclose engineering magic.  This is a gear pump, used to pump oil into a central heating boiler.  The meshing of the gears squeeze oil out from between the cogs forcing the oil down a pipe into the burner jet at high pressure.  Thankfully an new one is quietly doing its job in our boiler, but this one started to make a grinding noise and was condemned.  Taking it to bits revealed these beautifully precise gears.  Although not a true sun and planet gear system, the perfect crescent moon turns this engineering device into art that reflects the skies above.