⁠Earth and Moon: Formation, Characteristics of the Planet-Satellite System and their Orbital Dynamics

The Earth and Moon are bonded to each other with a strong gravitational force. Our Earth is the third planet of the solar system and the moon is its natural satellite orbiting around it. It is the nearest celestial body to earth. Both these celestial bodies influence each other such as the gravitational force of the moon causes high tides in ocean water. Let’s explore some interesting facts about the Earth and Moon, their formation, orbital distance and more.

Table of Contents

• Characteristics of the Planet-Satellite System
• How Earth and Moon Formed
• Orbital Distance between the Earth and Moon

Characteristics of the Planet-Satellite System 

The Earth and the Moon are a gravitationally bound planet-satelline pair. Our Earth is the 5th largest planet of the solar system and its Moon is a natural satellite which is 1/4th of its size. This glowing satellite of Earth plays a crucial role in stabilising Earth’s rotation. Its gravity is six times lesser than the earth’s gravity and it is the fifth largest satellite in our solar system. There are many such planet-satellite systems in our solar system, such as Mars and its two moons.

Covered with 70% water, it is the only terrestrial planet with life on it. Its atmosphere is made of oxygen and nitrogen. Earth’s diverse environment has oceans, mountains, grasslands and forests. Earth completes one rotation around its axis in 24 hours and one complete revolution around the sun in 365.25 days. It is composed of four main layers: the inner core covered by layers of outer core, mantle and crust. The earth’s diameter is 12,756 km and the Moon’s diameter is 3,476 km. From Earth we see the same part of the Moon every time as it takes the same amount of time to rotate on its own axis as it takes to orbit the Earth which is 27.3 days. 

How Earth and Moon Formed

The relation between the Earth and Moon is billions of years old and significant in the formation of the solar system. Scientists estimate that the Earth and Moon were formed 4.5 billion years ago from a massive cloud of dust and gas called solar nebulae. The swirling gases and dust particles in space joined together due to gravity and formed planetesimals. These building blocks of planets then combined to form earth. The Moon was formed later due to a collision between Earth and a mars-sized protoplanet. As a result of this collision some part of the Earth broke and the resulting debris collapsed into forming the Moon. 

Orbital Distance between the Earth and Moon

The average distance between Earth and Moon is around 3,84,000 kilometres or 2,39,000 miles. This distance between Earth and Moon is known as the lunar distance. The Moon is roughly 1/4th of the width of Earth and reflects the light from the sun. The sunlight reflected from the Moon takes 1.28 seconds to reach earth. A space craft usually takes three days to reach the Moon from earth. When we see the Moon changing shapes we see only some part of it that is reflecting sunlight while it is orbiting around its axes. Our Moon is 400 times closer to us than the sun. The gravity of the Moon is six times weaker than Earth but it impacts the movement of tides on Earth and we see high tides during the full Moon period.