The classical astronomers concluded that heavens were made up of a sphere, because heavens were thought to be perfect and spheres (circles) are a perfect shape. It was Plato who argued that geometrical figures were spheres and everyone agreed to him. It was also believed that the perfect motion of spheres was a uniform circular rotation.
Answer:
The correct answer will be- the planets and moon also exhibit hydrothermal vents, volcanoes and rocks.
Explanation:
Scientists have always tried to understand and explain the origin of life on Earth and predicted that life on earth originated as a result of the conditions created by the distance of the Earth from the Sun.
Later discoveries found that life exists even in the harsh conditions on Earth-like hydrothermal vents and inside sub-surface of the rocks. This shows that life can exist in extreme conditions.
Since the planets other than Earth posses such hydrothermal vents, rocks and volcanoes, therefore scientists predict that life could be found on other planets.