Why planets in the solar system lie on the same orbital plane?

With a wide variety of planets and other celestial bodies, the solar system is a fascinating and intricate area. The fact that all of the planets are located on the same orbital plane is one of the solar system's most noticeable characteristics. As a result, they all circle the sun at a same distance from its equator and have a similar tilt in relation to the solar's spin. However, why is that so?

image credit: Live Science

The formation of the solar system holds the key to the solution. The solar system is said to have originated from a vast cloud of gas and dust called a solar nebula. This cloud started spinning more and more quickly as it fell apart due to its own gravity. The cloud flattened down into a disk-like shape as a result of the spinning action, with the sun at its centre and the planets forming within the disc.

Small clumps of dust and ice started to develop as the disc cooled. These groups later developed into planetesimals, which are bigger bodies. The protoplanets that would eventually give rise to the planets we know today were created as the planetesimals collided and fused.

The protoplanets developed on the same plane as they did because all of the material in the disc was moving in the same direction and at a similar rate. All of the planets in our solar system now revolve on this plane, which is also referred to as the ecliptic.

The planets originated from a single disc that rotated around the Sun while it was in the centre, therefore their alignment and rotational axes were identical. This is another explanation for why the planets are located on the same orbital plane.

It is also important to keep in mind that while the planets all circle the sun on the same plane, their tilts toward the sun differ. Venus and Uranus have substantially greater tilts than other planets. This is probably because these planets were thrown out of alignment by other things in the solar system, notably Jupiter, whose gravity had an impact on them.

image credit: BBC Sky at Night Magazine

In conclusion, the solar system's planets evolved from the same spinning disc of gas and dust, known as a solar nebula, which explains why they all share the same orbital plane. The disc flattened down into a disk-like shape as a result of the disk's spinning speed, with the sun at its centre and the planets developing within the disc. The fact that the planets came from the same disc and rotate in the same direction is another factor contributing to their alignment.