The Beginning of Planet Formation
The four innermost planets of our solar system-Mercury, Venus, Earth, and Mars-are terrestrial, or rocky. planets. The beginning of their creation process occurred when the cloud of leftover material from the formation of the Sun settled into disc around the young star. Most of the material in the cloud, like the material of the Sun itself, was in the form of hydrogen and helium. But there was a trace of dust, no more than 2 percent of the original material, in the form of particles as fine as the particles in smoke. Heat from the young Sun blew much of the gas away, but the rotation of the original cloud ensured that the dust settled into a disc around the young Sun-a pro to planetary disc like the ones seen around young stars today.
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