Geologic Time Scale
Earth is born
4.57 billion years ago the Sun and the planets coalesced from a vast nebular cloud of gas and dust. About a million years later the Sun began shining when it accrued enough mass to ignite its hydrogen fusion furnace. The ensuing solar wind purged the infant solar system of much of its nebular origins, while leaving dust and debris, including asteroids and planetoids, in the plane of the ecliptic to be swept up by the forming planets.
This rendering suggests how the newly formed Earth and sun may have appeared shortly after the Sun's heat and solar wind cleared the inner solar system of cooler gases. The entire Earth is molten due to radioactive heating and frequent, heat-generating collisions with the remaining debris. Far above and below the Earth's orbit thousands of icy comets swarm around the Sun like bees around a hive. Some of these comets will eventually collide with the Earth and other planets, delivering water and other rare materials to these fledgling worlds.
Copyright © Walter Myers. All rights reserved.
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