Ron Clarkson, age 12, of Monroe, Michigan, for his question:
What was the earth like before it became solid?
Modern scientists tell us that our world was once part of a formless cloud of cosmic gases. There was no sun, no moon or other planets in the sky. Most astronomers now believe that our Solar System was first born in darkness before the sun became a blazing star.
Figuring the scope of the immense heavens is not an easy job. But at least the earth and other celestial bodies are on hand to be measured. Figuring the way these objects were in the remote past is far more difficult. Scientists have to deduce their origins from what they know of the cosmic laws that govern the behavior of matter and energy. For this reason, our ideas about the birth and early history of the earth are largely speculation. However, any modern scientific theory must have a great deal of reasonable evidence before anybody takes it seriously. The latest theory of the earth's early history is backed by masses of sound evidence, but no sensible scientist can say that it is definitely true.
Most astronomers accept the theory that our entire Solar System was formed from an immense cloud of hazy cosmic gases. At some time billions of years in the past, gravitational forces exerted themselves on the gaseous mass and formed it into a flat¬tish disk. Most of the material was concentrated in a central core. Smaller amounts were concentrated in circling rings around it. These embryos of celestial bodies are called the protosun, the protoplanets with their protomoons.
The third ring from the protosun was the unborn earth and its moon. It was a mixture of assorted gases and fragments of cosmic dust. The forces of gravity began to mold its material into a sphere, perhaps 500 times heavier and 2,000 times wider than our present planet. Its heavier elements tended to sink inward, forming a dense core surrounded by shells of lighter materials and a huge envelope of gases. So far the sun had been forming as a dark, cold mass. But at last the forces within it reached a critical state and that triggered nuclear reaction. For the first time, the infant earth was bathed in the light and warmth of its own starry sun.
Streaming radiation from the newly ignited sun stripped away masses of the earth's gases. Meantime, other reactions were triggered by heavy radioactive materials within the young planet. As these unstable elements decayed, they gave off tremendous heat. The landscape was a molten mixture of seething minerals. There were no seas, and moisture falling from the dense clouds boiled and shrouded the scenery in thick steam. In time radioactivity subsided and about four billion years ago the earth's surface became cool enough to form a solid crust.
We have a lot of sound scientific evidence to indicate that this is how things happened in the earth's infancy. But at present, this chain of events is merely a theory, a sort of educated guess. Astronomers, earth scientists and other researchers are still gathering evidence. If you choose a career in one of these fields, maybe you will find a scrap of new data. It just could be the one fact needed to prove our present theory true or false.