Earth’s layers

Subtitl

Earth's Structure

Geiger, B. (2019, November 11). Explainer: Earth — layer by layer. Science News Explores. https://www.snexplores.org/article/explainer-earth-layer-layer

OUTLER CORE

This part of the core is also made from iron an d nickel, just in liquid form. It sits some 5, 180 to 2,880 kilometers below the surface. Heated large by the radioactive decay of the elements uranium and thorium, this liquid churns in huge, turbulent currents. That motion generates electrical currents. They, in turn, generate Earth's magnetic field. For reasons somehow related to the outer core, Earth's magnetic field reverses about every 200,000 to 300,000 years. Scientists are still working to understand how that happens.

INNER CORE

This solid metal ball has a radius of 1,220 kilometers (758 miles) It's located some 6,400 to 5,180 kilometers beaneath Earth's surface. Extremely dense, it's made mostly of iron and nickel. The inner core spins a bit faster than the rest of the planet. It's also intensely hot: Temperatures sizzle at 5,400 Celsius. That's almost as hot as the surface of the sun. Pressures here are immense: well over 3 million times grater than on Earth's surface. some reaserch suggests there are may also be an inner, inner core. It would likely consist almost entirely of iron.

CRUST

Earth's crust is like a shell of a hard-boiled egg. It is extremely thin, cold and brittle compared to what lies below it. The crust is made of relatively light elements, especially silica, aluminum and oxygen. It's also highly variable in its thickness . Under the oceans , it may be as little as 5 kilometers thick. Beneath the continents, the crust may be 30 to 70 kilometers thick. Along with the upper zone of the mantle, the crust is broken into big pieces, like a gigantic jigsaw puzzle. These are known as tectonic plates. these move slowly - at just 3 to 5 centimeters per year. What drives the motion of tectonic plates is still not fully understood. It may be related to heat - driven convection currents in the mantle below. Some scientists think it's called "slab pull". In time, these plates will converge, pull apart or slide past each other. Those actions caus most earthquakes and volcanos.

ROTATION AND REVOLUTION

Rotation: The Earth moves around the polar axis following a west to east direction , and this causes the Sun to rise on the east and to set on the west. The exact duration of this spin is called a sidereal day, and 23 hours, but for practical reasons, the day is adjusted to 24 hours. We call it civil day. The rotation is what makes our days. Revolution: follows an elliptical orbit around the sun. The whole loop is completed in 365 days, and starts on march 21st. This is called a tropical year or solar year. The civil year starts on January 1st for practical reasons. The revolutionary movement determinates the seasons of the year; due to the revolutionary movement, the Earth moves closer and farther from the sun, and then light does not distribute homogeneously on the terrestrial surface. This is the reason of the season changes. According to the seasons, days and nights have different duration; the Sun has a different pathway closer to the south or north . Depending on the Revolution, meaning the position on orbit, you will only be able to see the stars that are in the opposite direction of the Sun.

Source: canvas student (n.d)ecology and geography https://cursos.tecmilenio.mx/courses/146451/pages/my-course?module_item_id=527791

MANTLE

At close to 3,000 kilometers thick, this is Earth's thickest layer. It starts a mere 30 kilometers beneath the surface. Made mostly of iron, magnesium and silicon, it is dense, hot and semi-solid. Like the layer below it, this one also circulates. It just does so far more slowly.