Question

About how long ago was the earth formed?
A) 3 billion years ago
B) 10 billion years ago
C) 4.6 billion years ago
D) 20 billion years ago

Answer 1

Hadean Eon is the first era in which the earth existed. This name comes from the Greek word "Hades" (underworld), which means condition of the planet at the time.The earth surface was under a continuous bombardment by meteorites and intense volcanism, which is severe due to the heavy heat flow and geothermal gradient dated on this era.

Complete answer:
Earth formed about 4.6 billion years ago. The cosmic material explosion threw hydrogen atoms and related nuclei in space which become condensed to formed nebulae. Nebula is a giant cloud which is formed by dust and gases present in the space .Through spinning each nebula is separated into many galaxies each of which holds together many stars by their mutual gravitational force. Earth originated as one of these stars.

Scientists have discovered that several billion years ago there was nothing in our Solar System but a cloud of cold dust particles spinning through empty space. This cloud of gas and dust was disturbed, because of the explosion of a nearby star and the cloud of gas and dust started to collapse as gravity pulls everything together, hence a solar nebula is formed —a huge spinning disk. As it spun, the disk separated into rings and the particles becomewhite-hot due to furious motion.

Hence the correct answer is option ‘C’.

Note: About 4.5 billion years ago, the particles in the outer rings change to large fiery balls of gas and molten-liquid that cooled and condensed to take on solid form .These solid forms began to turn into the planets such as Earth, Mars, Venus, Mercury, and the outer planets