The Earth and Solar System

Basics

The Solar system consists of the Sun at its centre with the Earth and seven other planets revolving around it.
Each planet moves in a path called an orbit.
The force keeping the planets in their orbits is the Sun’s gravitational pull.

The Earth spins on its axis once every 24 hours. This is called rotation.
The Earth’s rotation is what creates the cycle of day and night.
The Earth also moves around the Sun in an orbit, taking approximately 365.25 days. This is called revolution.
The tilt of the Earth’s axis and its revolution around the Sun cause the seasons.

The Moon is the Earth’s only natural satellite, orbiting the Planet roughly every 28 days.
The rotation of the Moon around its axis takes the same amount of time as it takes to orbit the Earth, hence we always see the same side of the Moon.
The apparent changes in the Moon’s shape, known as phases, are caused by its position relative to the Earth and the Sun.
The Moon affects Earth by causing tides due to its gravitational pull.

In addition to Earth and the Moon, the solar system consists of Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and the dwarf planet Pluto.
Planets are large bodies that orbit a star (in our case, the Sun). They are made up of rocks or gases and do not produce their own light.
Comets are composed of ice, dust, rock, and organic compounds and have highly elliptical orbits that bring them close to the Sun and then swing them back into space. When a comet gets close to the Sun, it forms a glowing coma and a tail that points away from the Sun because of the solar wind.

Beyond our solar system is the Universe, which includes everything that exists — from the smallest particles to the largest galaxies.
Galaxies are immense systems containing billions of stars and numerous clouds of gas and dust.
Our solar system is part of the Milky Way Galaxy.