Space Cadets! Get your binoculars and telescopes ready. Amateur astronomers are gearing up for a look at a new green comet. It’s called 103P/Hartley 2, and it’s already visible, with magnification, as a fuzzy smudge high in the northern sky, in the W-shaped constellation Cassiopeia. By Oct. 20, Hartley 2 will be just 11 million miles from Earth, and should be dimly visible to the naked eye. We’ll have more on the Weather Blog, later in the month.