Answer:
4.6; sun; planet; moons.
Step-by-step explanation:
Our Solar System was formed around 4.6 billion years ago from a giant cloud of gases and rocks that gravity pulled together. Most of the matter formed the sun while the rest formed planets, moons and other smaller bodies such as asteroids or large rocks.
A planet can be defined as a large celestial body having sufficient mass to allow for self-gravity and make it assume a nearly circular shape (hydrostatic equilibrium), revolves in an orbit around the Sun in the solar system and has a cleared neighborhood.
Basically, the planets are divided into two (2) main categories and these includes;
I. Outer planets: these planets are beyond the asteroid belt and comprises of jupiter, saturn, uranus and neptune, from left to right of the solar system.
II. Inner planets: these planets are the closest to the sun and comprises of mercury, venus, earth and mars.
These outer planets are made mostly of gases (hydrogen and helium) causing them to be less dense than the solid inner planets. These gases are generally known to be less dense in terms of physical properties.
Some examples of the planet are Mars, Venus, Earth, Mercury, Neptune, Jupiter, Saturn, Uranus, etc.
Furthermore, a force of gravity controls the movement of the planets around the sun in the solar system, holds together stars which are grouped in galaxies, as well as galaxies grouped in clusters.
This ultimately implies that, gravity is considered to be a universal force of attraction that acts between all objects that has both mass, energy and can occupy space. Therefore, it acts in such a way as to bring objects together.
Additionally, the gravity of earth makes it possible for all physical objects to possess weight.