Answer:
All of the planets travel around the Sun in the same direction, counterclockwise as seen from above the Sun's north pole, because they were formed from the same rotating disk of gas and dust that surrounded the young Sun about 4.6 billion years ago. This rotating disk of gas and dust, called the solar nebula, was slowly rotating in the same direction as the Sun's rotation. The planets formed from this disk by a process called accretion, where the particles in the disk collided and stuck together to form larger and larger bodies. Because the disk was already rotating in one direction, the planets formed from it also inherited the same direction of rotation, which is counterclockwise as seen from above the Sun's north pole.
The planets lie on a fairly flat plane, known as the ecliptic plane, because the solar nebula from which they formed was also a flat, rotating disk. As particles in the disk collided and stuck together to form larger bodies, their orbits would be constrained to lie roughly in the same plane as the disk, due to the conservation of angular momentum. This is because the angular momentum of a system remains constant unless acted upon by an external force, so any rotation in the system would cause the particles to flatten into a disk. This is also why most of the other objects in the Solar System, such as asteroids, dwarf planets, and comets, also lie on or near the ecliptic plane. The only notable exceptions are some comets, which have highly elliptical orbits that can take them far out of the plane of the Solar System.
Step-by-step explanation: