Como funciona o planeta Terra

Tracy Wilson

In the book "The Hitchhiker's Guide to the galaxy", Arthur Dent has trouble accepting the destruction of Earth by the Vogon fleet Builders. He can not process the information, the event is too large to be understood. He tries to focus on England, New York, in the films of Bogart and the dollar, all without result. It is only when he reflects on the demise of McDonald's hamburgers that finally comes to his senses.

Image courtesy NASA Earth from the Moon

After deciding to write about how the Earth works, we end up feeling a bit like Arthur Dent. Even though it is tiny compared to the rest of the universe, the Earth is huge and extremely complex.

But instead of thinking about the burgers, we decided to approach the subject differently. Instead of breaking the planet into pieces to examine it, let's examine what keeps parts together.

Energy and light

Newest Earth

Research indicates that Earth is 70 million years younger. Scientists point out that the planet took longer than was imagined to form.


Compared with the rest of the universe, the Earth is very small. Our planet and the other eight (or maybe nine) orbit the Sun , which is just one of 200 billion stars in our galaxy existing. And look what our galaxy, the Milky Way, is only a small part of the universe, which has millions of other galaxies (each with its stars and planets). So, by comparison, the Earth is microscopic.

On the other hand, when compared to a person, the earth is enormous. It has a diameter of 12,756 km at its equator, mass of about 6 x 10 24 kg and revolves around the Sun at a speed of about 29.79 km / s. These are impressive numbers, and almost inconceivable for our parameters. And look what the Earth has only a fraction of the size of the Sun.

Image courtesy NASA Earth and the Moon are tiny compared to the Sun, but the shadow of the Moon can cover it completely during an eclipse

From the perspective of who is on Earth, the Sun looks small, but this is only because it is more than 149 million miles of us. The diameter of the Sun at the equator is about 100 times larger than the Earth, and about one million Earths could fit inside the sun. Which makes it even more inconceivable than Earth.

Photo courtesy Athena Earth and Science The Sun

But without the sun, the Earth would not exist. In a way, the Earth is full of complex systems and moving parts giant machine. And all these systems need energy from the Sun.

The sun is a giant nuclear power plant, in which, through complex reactions, hydrogen is transformed into helium, releasing light and heat. Because of these reactions, each square meter of the surface of our planet receives about 342 watts of energy from the sun each year. If we add the entire surface, the total watts obtained from the Sun is 1.7 x 10 17 or the same amount that could be generated by 1.7 billion large plants [ ref  (in English)]. The only way the earth can generate more energy than the Sun would be if three people had their own collective power plant (and if the planet were large enough to contain all of them). If you want to learn how the sun creates its energy, see How the Sun works .

When this energy reaches the Earth, it allows a huge number of reactions, cycles and systems. It is what drives the circulation of the atmosphere and oceans and creates food for plants, which in turn are food for people and animals. Life on Earth could not exist without the sun and the planet itself would not have developed without it.

A world of beads

People often think of the earth as a blue ball or globe, although actually it is more like a pumpkin. But scientists classify the earth in various spheres:

  • atmosphere: the air we breathe;
  • biosphere or ecosphere: life on Earth;
  • geosphere: the layers of the planet;
  • hydrosphere: all water, including oceans, rivers and lakes;
  • cryosphere: the ice at the poles;
  • anthroposphere: people living on Earth.

To the casual observer, the most visible contributions to the life of the sun is light, heat and temperature. Let's take a look at how the sun provides all of that.

Night and day
Some of the biggest impacts of the sun on our planet are also the most obvious: as the earth rotates around its axis, parts of it are the Sun and others are in the shade. In other words, the sun appears to rise and set, and with this move, the world that are under the daylight get hotter, while the other parts are losing, gradually, the heat absorbed during the day .

You get the idea how the Sun affects the Earth's temperature to stay in one spot open for a partly cloudy day. When the sun is behind a cloud, you feel a far greater chill than when it was on display. The surface of this planet absorbs heat from the sun and emits the same way that asphalt continues to release heat in the summer, even after the sun had set. And our atmosphere also does the same thing: it absorbs the heat that emits the ground and send some of it back to Earth.

Photo courtesy of NOAA 's Earth's tilt is responsible for the seasons

This strong and lasting relationship of the Earth to the Sun is also responsible for the seasons. The Earth's axis tilts slightly (somewhere around 23.5 degrees). A hemisphere points toward the sun while the other points away from him. The first, which points toward him, gets hotter and receives more light and therefore it is said that it is in the summer. In the other hemisphere, therefore, it is winter. Because the region of the equator of the planet receives the same amount of sunlight throughout the year, this effect is less dramatic there than at the poles. The Poles, on the other hand, receive no sunlight during their winter months, which is part of the reason they are frozen.

Most people are so used to the differences between day and night (or summer and winter) that does not realize. But the truth is that these changes in light and temperature have a huge impact on other parts of our planet. One is the air movement through our atmosphere. 

  1. The sun shines on the equator and the air is getting hot as the equator faces the sun and the ozone layer is thinner in that region.
  2. As the air heats up, it begins to rise, creating a low pressure system. And the more he rises, the more it cools, causing the water condenses, clouds are created and the rains occur. And as the rain falls, the dry air, bringing warm and dry as a result, relatively high air in our atmosphere.
  3. Due to its reduced pressure, more air moves toward the equator from the North and the South. Gets warmer as it rises, pushing the dry air to the north and south.
  4. The dry air then reduces its altitude as it cools, creating areas of high pressure and deserts in the north and south of the equator.

The Sun and the Moon

The Sun also has to do with the moon. A light we see when the moon shines at night is actually reflected sunlight. Moreover, the relative positions of the Sun and Moon also create the solar and lunar eclipses. You are right that talking like that, it seems that the moon is nothing without the sun, but it also performs some important tasks for the Earth, for example, regulate the orbit and cause the tides there.

And this is only a part of how the Sun circulate air around the world. Ocean currents, weather patterns and other factors also play a role. But, overall, the air moves from high pressure areas to low pressure areas, much like the way when air is expelled from a bladder inflated when you let him out. The heat also tends to move the equator, it is warmer, to the poles, which are colder. To be able to view, imagine a hot drink on your table, and remember how the surrounding air gets warmer as the drink goes cold. Yeah, it happens to the earth, only in much larger scale.

The Coriolis Effect , produced by Earth's rotation, is another factor that affects this system, causing major weather systems such as hurricanes, spin. It helps create trade winds ranging westward near the equator and jet streams ranging eastward in the Northern and Southern hemispheres.'s those winds that move moisture and air from one location to another and create weather patterns ( the Coriolis Effect works on a very large scale, and does not actually affect the way water runs down the sink drain, as many people think).

Besides all that we have already quoted, is the sun that should receive much of the credit for the creation of winds and rains. When it heats the air in a specific location, this air rises and creates a low pressure area, causing more air come from areas around to fill that void, in a move that creates the wind. Without the sun, there would be no wind. And you know what else might not exist? Breathable air. Let's see the reasons for this in the next section.