Speculation about the origin and composition of our planet
Earth is as old as civilization itself. Most religions contain some form of
creation myth, and many hold that the natural forces governing the planet are
embodied by gods and spirits. In antiquity, various philosophers propounded theories
of the natural world. In the sixth century B.C., Pythagoras correctly noted
that the Earth is a sphere, and Aristotle offered plausible, but incorrect,
theories for volcanoes, earthquakes, fossils, and other natural phenomena.
Pytheas described the tides and noted that they are controlled by the Moon. By
the third Century B.C., Eratosthenes calculated the size of the Earth with
reasonable precision.
Before the Enlightenment of the 18th century most European
scientists were heavily influenced by religious belief, including the biblical story
of creation. Scholars attempted to fix the age of Earth through a careful and
literal reading of the Bible, concluding that creation took place about 6,000
years ago. But in the 17th century, a few scientists developed ideas that we
still believe to be correct today. In 1669, the Danish scientist Nicolas Steno
correctly explained fossils as the remains of long-dead organisms and
introduced the idea that layers of rock, later called strata by geologists,
were deposited at different times, with older layers lying below more recent
ones. In Scotland in 1785, an amateur geologist, James Hutton, suggested that
Earth's strata must have formed gradually. A half century later, another Scot, Sir Charles Lyell, argued strongly
that one could explain geologic history perfectly well by pointing to the
geological processes – the action of wind and water, earthquakes, and volcanoes
- presently at work and observable on Earth. Lyell rejected the short time derived
from the Bible and proposed a much greater period for the development and
evolution of Earth. Lyell's notion of a vastly great "geologic time"
made possible the evolutionary theory of Lyell's good friend Charles Darwin. It
provided the time scale necessary for natural selection to take place. (The New
York Times ‘Smarter by Sunday – 52 Weekends of Essential Knowledge for the
Curious Mind’)
