Question

how earth formed and why ❓

Answer 1

well there r many views about this one such is the Big Bang Theory which led to the formation of many planets including earth

Answer 2

hii, Your answer is here-
The Earth is thought to have been formed about 4.6 billion years ago by collisions in the giant disc-shaped cloud of material that also formed the Sun. Gravity slowly gathered this gas and dust together into clumps that became asteroids and early planets called planetesimals. Earth's rocky core formed first, with heavy elements colliding and binding together. Dense material sank to the center, while the lighter material creted the crust...... Gravity captured some of the gases that made up the planet's early atmosphere.Earth was completed within 10-20 million years.