Who said earth is a planet?

Answer 1

Scientific evidence suggests that life began on Earth approximately 3.5 billion years ago. The Earth formed 4.5 billion Years ago.

The Earth was a dead planet fore 4.5-3.5 = 1 billion years.

Some evidence would suggest that the first forms of life began more like 3.8 billion years ago, in which case the Earth was dead only 700 million years.

The beginning of life is called Abiogenesis.

If it worked the same on other planets on other Sun in other galaxies, life may have begin 10 billion years ago in other galaxies.

See related links.

Answer 2

The idea that the Earth is one of the planets follows from the heliocentric principle which says that the Sun is at the centre and the planets, including Earth, revolve round it.

The first person to construct a model with the Sun at the centre was Nicholas Copernicus. He was born in 1473 but his famous book, 'De Revolutionibus', was not published until 1543, the year he died, because he was nervous about being ridiculed for the theory.

Answer 3

not until after Copericus's theory of helo-centricity was understood.

Even the Greeks didn't have a clue.

Answer 4

It must be spherical in shape