The solar nebular theory explains the formation and evolution of the solar system. It is the most widely accepted model, also known as the "solar nebular hypothesis."
The nebular theory describes the formation of the sun, planets, moons and asteroids around 4.5 billion years ago from a nebula cloud comprising dust and gas, according to Universe Today. Gravity condensed the gas into dense regions, which grew into clumps of matter. The nebula cloud spread to form a rotating disk that became the plane of the solar system, which is still in evidence because all planets orbit around the sun in the same direction and plane.
Formation of the sun
The least amount of centripetal force was at the center of the rotating disk, so most of the mass from the nebula cloud became attracted to this area due to the force of gravity. Most of the material was hydrogen gas that came under intense pressure, which heated it to a critical point, leading to it fusing with another hydrogen atom, creating helium and giving birth to the sun.
Formation of planets and the moon
The clumps of matter grew in size to form planetismals, or early planets, slamming into one another as they orbited the early sun. According to nebular theory, an early form of planet Earth collided with an object, causing debris to fly into space, which then reformed within the Earth's gravitational field to form the moon.Learn More
Since there are no physical boundaries in space, the solar system is often regarded as the distance from the sun to Neptune, which is approximately 30 astronomical units and equals approximately 2,790,000,000 miles. Astronomical units, which are used by astronomers, each equal 93 million miles.Full Answer >
The nearest star to the solar system is the Sun, but the nearest star to the solar system excluding the Sun is Proxima Centauri. The Sun is located about 93 million miles away from Earth, while Proxima Centauri lies about 4.22 light years away.Full Answer >
The nebular theory of solar system formation suggests that stars and their planets form out of cooling interstellar clouds of molecular hydrogen. As the cloud contracts, it forms a disc of dense material that forms the star. As it forms, the star throws off material that coalesces into planets.Full Answer >
Comets are made up of collections of ice, dust and rocky particles that are leftover from the formation of the solar system 4.6 billion years ago. Comets range in length from a few kilometers to tens of kilometers. The nuclei are comprised of frozen gases such as carbon dioxide, carbon monoxide, methane and ammonia.Full Answer >