GOCE (flaring satellite)
BRIGHTNESS: 3 (dim but visible)
Europe's Gravity field and steady-state Ocean Circulation Explorer ("GOCE" for short) is an extraordinary spacecraft. It circles the planet at a perilously low altitude using fins to cut through the wisps of Earth's outermost atmosphere. GOCE's sophisticated ion engine constantly adjusts its thrust between 1 and 20 millinewtons (mN) to counteract even the slightest hint of atmospheric drag. All this is necessary to make the finest-ever maps of Earth's gravitational field. For sky watchers, the best thing about GOCE is that it flares like a meteor when sunlight glints from its solar panels. The brightness of the flares is similar to the stars in the Big Dipper.