Astronomy Cast Episode 225-Ice in Space

Many thing in our solar system are made of ice, for example, comets, rings, moons, and some dwarf planets.  Recently, astronomers have asked the question, "where does all this ice come from?"


To begin, astronomy cast traveled to NASA to discuss plans involving the New Horizons mission, which plans to send spacecraft to the dwarf planet of Pluto, and beyond.  This mission plans to capture images of many items in our solar system that are composed primarily of ice.  They learned that there is a freeze line that exists somewhere in between Jupiter and Saturn, and once that line is crosses, ice becomes extremely evident in many celestial objects, such as the rings of Saturn.  In the outer solar system, however, you enter a region where most objects are composed completely of ice, as opposed to partially made of ice.


We believe that many of these objects are formed where they currently exist, which explains and supports the existence of the freeze line.  Parts of the Oort Cloud and Kuiper Belt are believed to have formed elsewhere, and were pulled into orbit by larger, stronger gravitational forces.  Scientists have studied where and how the objects have formed.  They have concluded that ice can form, not just from water, but from any molecule capable of vaporizing when exposed to extremely high temperatures.  In the early solar system formed, the sun emitted many atoms and other such items, which eventually became solids once they reached the outer area of the solar system, where it was cold and the warmth of the sun had little effect.