A solar nebula is a rotating cloud of gas and dust from which the sun and the planets formed.
A planetesimal is a small body from which planet originated in the early stages of development of the solar system.
Kupier belt is region of the solar system that is just beyond the orbit of Neptune and that contains bodies made mostly of ice.
This is the region of the solar system that contains small bodies that are made mostly of ice.
Thus Pluto is formed from the huge disk of ice and debris beyond the outer planets. Comets originating from the Kupier belt are also composed of ice and debris.
When an atom of the unstable isotope Na-24 decays, it becomes an atom of Mg-24 because the Na-24 atom spontaneously releases (2) a<span> beta particle</span>.
