How the Earth Works

The sun's massive power source has two main disadvantages --ultraviolet lightand thesolar wind。Ultraviolet light can cause癌症, cataracts and other health problems. The solar wind, a stream of charged, orionized, particles that stream off of thesun, could strip away our atmosphere. Fortunately, the Earth has some natural defenses against both. Ourozone layerprotects us from ultraviolet (UV) light, and ourmagneticfieldprotects us from the solar wind.

Thestratosphere, the layer of atmosphere just above the one in which we live, contains a thin layer of ozone (O3). This layer wouldn't exist without the sun. Ozone is made of three atoms of oxygen. It's not a very stable molecule, but it takes a lot of power to create it. When UV light hits a molecule of oxygen (O2) of, it splits it into two atoms of oxygen (O). When one of these atoms comes into contact with a molecule of oxygen, they combine to make ozone. The process also works in reverse -- when UV light hits ozone, it splits it into a molecule of oxygen and an atom of oxygen.

This process is called theozone-oxygen cycle, and it converts UV light into heat, preventing it from reaching the surface of the Earth. Without the sun, the Earth wouldn't have an ozone layer -- but without the sun, the Earth also wouldn't need it.

But while the sun creates the ozone layer, the Earth itself creates its defense against the solar wind. Without the Earth's magnetic field, ionized particles from the solar wind could strip the planet's atmosphere away. This magnetic field comes from deep inside the Earth's core. Interactions between theinnerandouter core创建磁场。

The planet's inner core is made of solid iron. Surrounding the inner core is a molten outer core. These two layers are very deep within the Earth, separated from itscrustby the thickmantle。地幔是固体但可塑的,像塑料,and it's the source of the magma that comes fromvolcanoes。

地球的内部核心旋转，就像地球在其轴上旋转。外芯也旋转，并且以与内芯不同的速度旋转。这会创建一个dynamo effect, or convections and currents within the core. This is what creates the Earth's magnetic field -- it's like a giantelectromagnet。When the solar wind reaches the Earth, it collides with the magnetic field, ormagnetosphere, rather than with the atmosphere.

The poles actually change places periodically -- about 400 times in the last 330 million years. The field weakens while the shift takes place. But computer simulations predict that the sun might come to the rescue, interacting with the atmosphere to supplement the magnetic field, while the shift is in process.

The Earth's physical composition generates its magnetic field. That composition is a product of the Earth's creation, which would not have been possible without the sun.