Earth

The earth is the planet on which we all live, along with a whole lot of other organisms. Of all the planets we currently know (including those outside our own solar system), Earth is as far as we know the only one with living beings. Earth is a stone planet and is also called the 'blue planet'. The Earth also has one moon. Scientists at Wikimini calls it the spaceship earth and points out to all of us the vulnerability of the earth.

What does the earth look like?

From the sky you can see that the Earth is 70% blue, so actually sea or water. Furthermore, you also see pieces of green, which are the continents. That's seven. The seven continents are: Europe, Asia, Africa, Oceania, North America, South America and Antarctica. Those seven continents are again further divided into countries by the people. You also see white picks, which are clouds.

The earth has the shape of a sphere. People used to think that the earth was flat and that if you walked or drove too far, you could fall off the earth. But of course that is not possible, not only because the earth is convex, but also because of gravity it is impossible to leave the earth without a lot of speed. Only rockets and space probes can do this.

A few details

• The surface of the earth is 510,100,933 km².
• The total distance around the equator is 40,076 km, but measured across the poles is 40,009 km.
• The earth revolves around the sun in one year and six hours. So after 4 years this is a whole day and we pasted it on February 29. A year with that date is called a leap year and that is one day longer than an ordinary year.
• The Moon rotates around the earth and takes about 29 and a half days.
• The average temperature there is 14 °C.

History

The Earth is estimated to be 4.5 billion years old. It is believed to have originated from the dust and debris of previous celestial bodies. The Moon must have formed at the same time or a little later, but we don't know exactly how. Perhaps there was a huge collision between the earth and another planet, called Theia, after which the Moon formed from the loose debris.

When she had just been born, the earth was still very hot from the outside. Then it gradually cooled down and formed the earth's crust.

It is estimated that the very first life on Earth arose about 3.5 billion years ago, but these were only microbes. Only much later did more complicated organisms come and real people are only there for a few million years.

People used to think that the earth was flat and that there was an end of the world; therefore, in some places there were signs with "End of Earth". Today we know better: the earth is round.

Position in the solar system

Earth is one of the total 8 planets that orbit the sun. It is the fifth planet in size and the third planet from the sun in our solar system; it is just under 150 million kilometres from the sun.

In the Middle Ages, people thought the earth was the centre of the universe. We call this view geocentrism.

The inside

The inside of the earth consists of the earth's crust, the outer mantle, the transition zone, the inner mantle, the outer core and the inner core. The earth can be compared to an egg, as the shell is the earth's crust, that skin below is the outer mantle, so the white part consists of two parts, the transition zone and the inner mantle, then there will be a dark orange piece - that is the outer core - and finally the inner core. The earth's crust is 0 to 40 km long, the outer mantle is 40 to 400 km long, the transition zone is 400 to 900 km long, the inner mantle is 900 to 2900 km long, the outer core is 2900 to 5100 km long, inner core is 5100 to 6371 km long. If you are above the earth's crust, you are on land.

On the basis of seismological research, scientists have determined that the earth has a solid nucleus (of multiple layers), consisting of iron and nickel.

Orbit of the Earth

The earth does not rotate in a circle around the sun, but in a kind of oval, also called an ellipse.

The earth is a little crooked, about 23 degrees. It rotates in 23 hours, 56 minutes and 4 seconds, once around its own axis. The difference is because the earth not only revolves around its axis, but also around the sun. After 23 hours, 56 minutes and 4 seconds, the stars are back in the same place in the sky. That time is why we also call a star day. Sometimes you come across the name sidereal rotation period for this. After 23 hours, 56 minutes and 4 seconds, the stars are in the same place in the sky, but the sun is not yet. Because the earth has now also moved a little further into its orbit around the sun, we have to wait another 3 minutes and 56 seconds before the sun is exactly in the same place. The time course of 24 hours is also called one sun day. In exactly one year, the earth revolves once around the sun.

The orbit of the earth around the sun

The earth rotates in different ways. She revolves around her own axis and the sun. If she rotates around her own axis, she does so in 24 hours. This is called an day. The earth's axis is at an angle of 23.4°. This means that the earth is not upright but slightly bevelled. This causes the seasons. The distance between the sun and the earth is 150 million kilometres. The light you see during the day takes 8.5 minutes to reach the earth. The earth rotates around the sun in just over 365 days (365 and a quarter of a day). When the earth has made its orbit around the sun, it has made a distance of 942 million kilometres. The orbit is not a perfect circle, in which the distance to the sun would always be the same, but an ellipse: that is a longer stretched orbit. The sun is not exactly at the centre of it, but in one of the focal points of that ellipse. The earth has the smallest distance to the sun when it is winter in the northern hemisphere and the largest when it is summer there.

Seasons on Earth

The four seasons consist of:

1. Spring: starts on March 20 or March 21. The word spring is derived from 'long', which means the lengthening of the days.
2. Summer: starts on June 20 or June 21. The name is derived from the word 'summer', which means 'in the middle of the year'. This is the hottest time of the year.
3. Autumn: starts around 22 or 23 September. Autumn is derived from 'revest' or 'harvest', and means harvest.
4. Winter: starts on December 21 or 22. Winter is derived from 'hiems' or 'frost' and means thunderstorm or frost. It is the coldest period.

There are two types of seasons: the astronomical and the meteorological. The astronomical seasons are the seasons we use to indicate which season of the year we are in. The meteorological seasons often begin on the first day of the month in which the astronomical seasons begin. So a meteorological season starts a little earlier. This has to do with the fact that the weather often changes earlier to the coming season.

The seasonal differences arise from the oblique position of the earth's axis around which the earth rotates. As a result, the sun in the northern hemisphere rises higher above the horizon in summer than in winter. As a result, the sun shines longer in summer than in the other seasons and therefore it is also warmer in summer. In winter, it's just the other way around.

Because the earth is a bit crooked (obline earth axis), in December the northern hemisphere is turned away from the sun. In the northernmost area, the sun is not visible at all. Even in the middle of the day it is as dark here. We call it the 'pool night'. While it is dark at the North Pole in December, Antarctica - the South Pole - gets plenty of light. The sun can always be seen here in December, day and night. The sun is just above the horizon, but does not set. We call that the 'midnight sun' or 'pool day'. Europe gets the most sun in June, then the sun shines in the northern hemisphere and we have long days and short nights. In December we see the sun much less in Europe. We have short days and long nights. The sun is then focussed on the southern hemisphere.