Each time you look up to the sky and see a star you are looking at a sun in another galaxy. If you were on another planet looking back at our solar system, you would see our sun as a star.

It’s believed that every sun has planets orbiting it. Our Milky Way galaxy has more planets than it has stars. In our solar system we have eight planets: Mercury, Venus, Earth, and Mars are the inner rocky planets. Jupiter and Saturn are the outer gas giants. Uranus and Neptune are the outer ice giants.

In recent years, astronomers have designed a new class called the “dwarf planets.” These are smaller worlds, not quite big enough to be considered a standard planet, and include Pluto. Earth is the third planet from the sun.

Earth Statistics:

  • Population: 7.53 billion (2017) Trending, World Bank
  • View on Maps:
  • Distance from Sun: 92.96 million mi
  • Radius: 3,959 mi
  • Polar Diameter: 12,714 km
  • Orbital Period: 265.24 days
  • Mass: 5.972 × 10^24 kg
  • Number of Moons: 1
  • Age: 4.543 billion years

How did Earth get its name:

It’s believed that the name “Earth” is around 1,000 years old. If you notice, except for Earth, all of the planets in our solar system are named after Roman and Greek gods and goddesses. One idea of the source of the name is that the word “Earth” is an old Germanic word that really just means “the ground.”

Another thought is that the name “Earth” is derived from the Old English word “ertha” as well as the Anglo-Saxon word “erda”, which means soil or ground.

Earth is the only known planet to support life and was formed around 4.54 billion years ago.

Astronomers of ancient times thought that the Earth was the center of the universe and the sun as well as all of the planets orbited around Earth.

They also thought that the Earth was static and never changed or moved. This idea was part of many cultures for over 2,000 years. It wasn’t until 1543 when Copernicus created his published work of the Sun-centered Solar System model that fellow scientists realized that the sun was the center of the solar system and Earth revolved around it.


About 4.5 billion years ago, our solar system settled into the layout that we see today. It’s believed that Earth formed when gravity began pulling dust and swirling gas together, and the Earth became the third planet from the sun. Earth is one of the terrestrial planets, which means it has a central core, rocky mantle, and a crust that is solid.

Our Earth orbits the sun every 23.9 hours and it takes 365.23 days to complete an entire trip around the sun. The axis of rotation of the Earth is tilted 23.4 degrees and it’s this tilt that gives us our seasonal cycles every year.

Structure and Surface:

The Earth is made up of four main layers, beginning with the planet’s inner core which is enveloped by the outer core, then the mantle, and finally the crust. The inner core is around 759 mi/1,221 km in radius and is a solid sphere of nickel and iron metals.

The temperature of the inner core is as high as 9,800 degrees F/5,400 degrees C. Surrounding the inner core is the outer core, which is 1,400 mi/2,300 km thick. The outer core is made up of iron and nickel fluids.

Wedged in between the outer core and the crust is the mantle which is the thickest of all of the layers. This is a hot, thick mixture of molten rock that has the consistency of caramel and is around 1,800 mi/2,900 km thick.

The Earth’s crust is the outermost layer and is an average of about 19 mi/30 km deep on land. The ocean’s bottom has a thinner crust and it extends about 3 mi/5 km from the floor of the sea to the top of the mantle.

Just like Venus and Mars, Earth has mountains, volcanoes, and valleys. The “lithosphere” of the Earth includes both the oceanic and continental crust as well as the upper mantle.

It is divided into huge plates called “tectonic plates” that are constantly in motion. This movement causes the plates to collide to create mountains, split or separate, or rub against each other and create earthquakes.

Structure of the Earth
The Earth has an ocean that covers almost 70% of the surface of the planet. The average depth of the ocean is around 2.5 mi/4 km and contains 97% of the water on the Earth.

Almost every one of the volcanoes on Earth is hidden under these oceans. The Mauna Kea volcano in Hawaii is taller from the base to the top than Mount Everest, but a majority of the volcano is underwater.

The longest mountain range on Earth is also underwater, at the bottom of the Atlantic and Arctic oceans. This mountain range is four times longer than the Rockies, Andes, and Himalayas all combined.

The land masses that make up 30% of the Earth’s surface are incredibly varied. Land has continents, islands, and other land masses as well as sources of fresh water.

Many scientists believe that water was delivered to the Earth by comets and asteroids as it was forming and that much of the water was inside the planet and then brought up to the surface during volcanic activity.

Atmosphere. Magnetosphere, and Moon Status:

Earth’s atmosphere consists of 78% nitrogen, 21% oxygen and trace amounts of other gases including carbon dioxide, argon, and neon. We give credit to the plant life on Earth for generating the large amount of oxygen.

Earth's atmosphere
During the photosynthesis process, plants consume carbon dioxide and give off oxygen. Earth’s Ozone layer consists of a special kind of oxygen that helps to absorb the harmful UV rays from the sun.

The Ozone layer protects Earth and life from the extremes of solar radiation. Our atmosphere is also responsible for both short-term and long-term weather effects on the Earth.

The atmosphere acts as a protective barrier, shielding the Earth from the impacts of meteoroids as many burn up before they have a chance to hit Earth’s surface.

The magnetic field of Earth is incredibly powerful and also plays a big part in protecting our planet from the effects of solar wind. It’s though that the Earth’s magnetic field is due to the planet’s core, which is made up of nickel-iron, combined with the fast rotation of the Earth.

It’s important to realize that the rotation of the Earth is slowing down at nearing 17 milliseconds for every 100 years. The slowing down process will have an effect on the length of our days, however, it will take around 140 million years before we see a day change from 24 hours to 25 hours.

The solar wind distorts the magnetic field so that if you looked at it in space it would be a teardrop shape. The solar wind is a constant stream of charged particles that the sun ejects.

When these particles are trapped in the magnetic field of the Earth they collide with the molecules in the air above the Earth’s magnetic poles. This collusion causes the molecules in the air to glow and this is known as the Aurora Borealis or northern and southern lights.

It’s the Earth’s magnetic field that causes the compass needles to point to the North Pole, no matter which way that you turn. However, the magnetic polarity of the Earth doesn’t always stay the same, and the magnetic field can flip.

Scientists studying geological records have seen that there is a magnetic reversal every 400,000 years or so. As far as anyone knows, this flip hasn’t caused harm to Earth’s life, and another one isn’t likely to happen for at least another thousand years.

It’s guessed that when a flip does occur, compass needles will point in many different directions for a few centuries until everything settles down; and then the compasses will point south instead of north.

Earth has one moon and no rings.

Could Life Exist?

If you look around our Earth you can see that we have an incredible amount of life that exists on both the land and within the waterways and seas. Scientists have always based our definition of “life” as the carbon-based type that we have around us, including ourselves.

They established three rules that are required for life: liquid water, some source of energy such as our sun, and a source of food. However, in the past number of years experts have discovered Earth lifeforms that live outside of these ideas.

These lifeforms live in conditions that were previously thought to be uninhabitable, and they are called “extremophiles.”

Scientists believe that life not only developed but adapted and thrived on Earth because of our uniquely perfect distance from the sun and the gravitational effects that the moon had on the planet.

Earth isn’t too hot and isn’t too cold, and this is often called the “Goldilocks distance.” Our moon has created the tides on Earth, which in turn has helped life to develop.

The rotation of the moon around the Earth has caused an effect that is called being “tidally locked” so that the orbit and rotation periods are the same. This lock is what causes the moon to always be facing the same way to Earth.

The size of the Earth and the distance from the sun is critical to life on Earth. The Earth is the largest of the terrestrial planets at 3,959 mi/6,371 km radius, and the fifth largest overall planet in our solar system.

Earth is an average distance of 93 million mi/150 million km from the sun or one AU (astronomical unit). An AU is the distance from the Sun to the Earth. It takes around eight minutes for light that leaves the sun to reach the Earth.

Space Visits:

We have thousands of satellites orbiting the Earth to study specific areas as well as the entire Earth as a whole. These satellites observe the atmosphere, glaciers, oceans, and the solid earth.

Many of these satellites are also communication satellites, bringing us our cable television and our cell phone service.

Facts about Earth for Kids:

  • The shape of the Earth is actually closer to a squashed sphere. It’s fatter in the middle near the equator where gravity pushes to create a bulge.
  • Even though you might think you are standing still, the Earth is turning. The speed at the equator is around 1,000 mph.
  • The Earth is also moving through the solar system at around 67,000 mph/107,826 kph.
  • Earth is constantly recycling its material through tectonic movement which drags surface rocks back down below the surface to become magma and then is spewed back out from volcanoes.
  • Earthquakes are the result of tectonic plate movement on the planet. The largest earthquake recorded in the U.S. was in 2016 in Alaska, registered at 9.2 on the Richter Scale; with the largest global earthquake recorded in 1960 in Chile, registering 9.5 on the Richter Scale.
  • The hottest recorded temperature location on the Earth is in El Azizia, Libya with temperatures hitting 136 degrees F/57.8 degrees C in 1922.
  • The coldest temperature location is in Antarctica with temperatures reaching -100 degrees F/-73 degrees

Pop Culture:

Discovering the nature of our home planet has been the topic of many books, movies, and television shows.

The well-known movie (and its sequels) “Planet of the Apes” occurs in a future where our astronauts find that intelligent apes have taken over the world and the primitive animals are the human beings.

The long-running television series and its remake “Battlestar Galactica” include a band of a war against the highly evolved cylon robots, while they search to find the long lost colony of Earth.

In many tales, writers have left the Earth as destroyed or abandoned. The television series “Firefly” and the book and film adaptation “The Hitchhiker’s Guide to the Galaxy” are two such stories. “Titan A.E.,” the animated feature shows Earth’s destruction by a species of aliens, however, a well-placed planet builder then recreates the planet and all of the species that live on it.

Earth has remained as a base for other space exploration stories, including the iconic “Star Trek” series. Originally created by Gene Roddenberry, Star Trek uses Earth as a leading member of The Federation of Planets and the many spaceships that head out to explore galaxies and beyond.