[BRIEF NOTE] The Snow Line

[rfmcdonald]

Out of the thousands of cubic astronomical units of space that make up the inner Solar System, only a small percentage is to be found within the snow line, "the annulus within a protostellar disk beyond which water molecules can efficiently condense to form ice," founded early in the Solar System's history between the orbits of Mars and Jupiter. Earth is inside this boundary, and so, like many of the asteroids and like the adjacent Earth-like planets of Mercury, Venus, and Mars, is rocky, with only a thin covering of water. Outside the snow line is the empire of ice, in the Galilean moons of Jupiter, in Saturn's moon of Titan, on distant Neptune's Triton, and on all of the smaller moons, comets, and other bodies to be found in these spaces. Of all of the rocky worlds found within the snow line, Earth--because of its temperate location, its significant mass, and other reasons--is the only planet where molten dihydrogen monoxide condenses out of atmosphere on a regular basis.

Not always, mind, and not consistently: There's nothing like digging out a path to your basement apartment, through the stairwell, through a foot and a half of snow to make one realize this. Still, spring will come and my alley's clear, so how can I complain?