What is the origin of Earth?

Answer 1

When the sun began to form, clouds of gas formed in rings around the sun. They eventually coalesced into gaseous balls orbitting the sun. These proto-planets consisted mainly of hydrogen and helium, and thus could not have formed into the rocky planets. However, they did have gravitational fields and they were able to sweep other matter up from interstellar space.

The fusion process in stars, such as our sun, will eventually produce abundant light elements, but very little of the heavy elements. However, from time to time a supernova star explodes at such high temperatures as to produce the heavy elements of our planetary system. Each supernova scatters its matter into interstellar space, to be attracted towards other stars and solar systems such as our own. Over the eons, some of this was accumulated by the planets, including our own, Earth.

These balls cooled, to become the planets we know today. But they still had massive atmospheres consisting mainly of hydrogen and helium. The larger planets, such as Jupiter, with their greater gravity, were able to retain those lighter gases and are today the "gas giants". Intermediate planets, such as Earth and Venus, gradually lost most of the gaseous hydrogen and helium, but retained the heavier gases, such as oxygen and nitrogen. Smaller planets, with their weaker gravitational fields, gradually lost nearly all their atmospheres.

Thus, the Earth formed, as one of the planets in our solar system, at first into a barren planet, hostile to life forms.

Answer 2

The two most widely-known answers are the tradition of Creation, and the theory of the Big Bang followed by Evolution. According to the theory of the Big Bang followed by evolution, the Universe (and this Earth) resulted from random events stemming from natural laws, and life then developed by random processes, especially mutations.

The narrative of Divine Creation, which is contained in Genesis ch.1 and 2, states that God created the universe. This teaches us that God exists, that our lives and the world are not random, and that the created things may be assumed to contain vast wisdom in their beautiful and purposeful design. (In recent decades, this wisdom has indeed been partially revealed, through increasingly powerful microscopes.)Evolution through random mutations, on the other hand, may be understood as implying that life is an accident, that perceived beauty and wisdom are ultimately purposeless, and that our instinctive yearning for the Eternal is just an electrical impulse in our brain.

See also:

Is there evidence against Evolution