The most widely accepted model to explain the formation and evolution of the solar system is the:

The nebular hypothesis is the most widely accepted scientific explanation of how the solar system formed. It states that the Sun, planets, moons and other bodies formed about 4.6 billion years ago from a huge, slowly rotating cloud of gas and dust called the solar nebula.

The idea was first proposed by the German philosopher Immanuel Kant in 1755. In 1796, the French mathematician Pierre-Simon Laplace developed it further; it is therefore often called the Kant-Laplace nebular hypothesis.

According to the modern version of the theory (the solar nebular disk model):

• A giant cloud of gas (mainly hydrogen and helium) and dust began to collapse under its own gravity, possibly triggered by the shock wave of a nearby exploding star (supernova).
• As it collapsed, it began to spin faster and flattened into a rotating disk (a protoplanetary disk), with most of the mass at the centre.
• The centre became very hot and dense and formed the Sun, when nuclear fusion of hydrogen began.

In the disk, tiny dust particles stuck together to form larger bodies called planetesimals, which collided and merged to form protoplanets and finally planets. This process is called accretion.

Close to the Sun, where it was hot, only rocky and metallic materials could condense, forming the terrestrial planets (Mercury, Venus, Earth and Mars). Farther away, beyond the "frost line", ices could form, and the planets grew large enough to capture huge amounts of hydrogen and helium gas, forming the gas giants (Jupiter and Saturn) and ice giants (Uranus and Neptune).

Leftover material formed asteroids, comets and dwarf planets.

This model explains why all planets orbit the Sun in the same direction and in nearly the same plane. Observations of young stars with protoplanetary disks, by telescopes such as ALMA and the Hubble and James Webb space telescopes, support the theory.

Other older theories:

• Tidal hypothesis (James Jeans and Harold Jeffreys, 1917-19): planets formed from material pulled out of the Sun by a passing star.
• Planetesimal hypothesis (Chamberlin and Moulton, 1904).
• Binary star hypotheses.
• These have largely been abandoned.

Why not the other options?

• ✗The tidal hypothesis of Jeans and Jeffreys is no longer accepted.
• ✗The planetesimal hypothesis of Chamberlin and Moulton is an older theory.
• ✗The steady state theory (Hoyle, Bondi and Gold) dealt with the universe, not the solar system, and has been rejected.