Planet home: Earth

Hello readers! I was just brushing up on my knowledge on this world that we currently reside on, and figured that I would dedicate a post to all the things I've learnt about Earth!

                              

Cool facts about the Earth:

• The Earth's rotation is gradually slowing. This has the effect of lengthening our days but it happens so slowly that it could be as much as 140 million years before the length of a day will increase to 25 hours
• The Earth was once believed to be the centre of the universe, eventually, the view that the Sun was at the centre on the universe was postulated by Copernicus and eventually was shown to be the case
• Earth has a powerful magnetic field, caused by the nickel-iron core of the planet coupled with its rapid rotation. This field protects the Earth from the effects of solar wind
• There is only one natural satellite of the planet Earth - the Moon!
• Earth is the only planet not named after a god; the other seven planets in our solar system are all named after Roman gods or goddesses. Mercury, Mars, Jupiter and Saturn were named during ancient times as they were visible to the naked eye and the Roman method of naming planets was retained after the discovery of Uranus and Neptune.
• The Earth has the greatest density of all the planets in our solar system  
• Many layers of atmosphere coat our planet including the mesosphere, ionosphere, exosphere, and the thermosphere, but it’s the troposphere, closest to the planet itself, that supports our lives and is, in fact, the thinnest at only about 10 miles high.
• Most of the Earth’s deserts are not composed entirely of sand. About 85% of them, are rocks and gravel. The largest, the Sahara, fills about 1/3 of Africa
• The Earth is, in fact, not really round. It is called an oblate spheroid meaning it’s slightly flattened on the top and bottom poles.

What is the Earth made of?

The Earth has multiple layers. The ocean basins and the continents compose the crust which is the outermost layer. Earth's crust is between three and 46 miles (deep. The thickest parts are under the continents and the thinnest parts are under the oceans.

• The crust: it is made up of several elements: iron, oxygen, silicon, magnesium, sulfur, nickel, and trace amounts of calcium, aluminium and other elements. It is divided into huge plates that float on the mantle, the next layer. The plates are constantly in motion. Mountains form when the plates collide and deep trenches form when one plate slides under another plate. Plate tectonics is the theory explaining the motion of these plates.
• Mantle: it is under the crust and about 1,800 miles deep. It is composed mostly of silicate rocks made up of magnesium and iron. Intense heat causes the rocks to rise. They then cool and sink back down to the core. This convection is believed to be what causes the tectonic plates to move. When the mantle pushes through the crust, volcanoes erupt.
• the core: at the centre of the Earth, it is made up of two parts. There is a solid, inner core of iron which has a radius of about 760 miles and is surrounded by a liquid, outer core composed of a nickel-iron alloy. The inner core spins at a different speed than the rest of the planet and it is this which is thought to cause Earth's magnetic field. 

Thanks for reading!