Pressure also increases in the outer core due in part to the weight of the crust and mantle above. The outer core consists mainly of liquid iron, along with substantial amounts of nickel and sulfur. The Earth’s magnetic field is generated by the outer core.

As you move through the layers the closer you get to the core the warmer it becomes. What are the two causes of the high temperatures within the Earth? The high temps are a result of heat left over from the formation of the planet and also the radioactive substances inside that release energy.

Convection currents are circular movements based on temperature and density. The heat from deep inside Earth heats the semi-fluid particles of the asthenosphere. These particles then up become less dense and rise. As they rise to the bottom of the crust, they cool off, become denser, and move back toward the core.

Although the inner core is hotter on average than the outer core — approaching 5,000 degrees Celsius — it is solid because the center of the Earth is under higher pressures than outer layers. The inner core is at pressures 3 million times higher than what we experience on land on the Earth’s crust.

Flickr/Beverly & Pack A normal, healthy person might have 10 minutes to an hour, or six hours to 36 hours — depending on whom you ask — before settling into a premature grave. Scientists disagree, but one thing’s for sure: it wouldn’t be long. It all comes down to the amount of air available in the coffin itself.

Living entirely underground would be unprecedented, to the point of being nearly unfathomable. But experts say with good design and a lot of psychological support, humans could make convincing—and surprisingly healthy—mole people. Good thing, too, because the above world is looking increasingly inhospitable.

We know that all plants require a certain amount of sunlight to make food and survive, through a process called photosynthesis. Humans get our energy from the food we eat, and all of that food is derived from the energy of the sun. So, we need the sun to survive.

When a lack of sunlight keeps us from sleeping well and causes us to become vitamin D deficient, our immune system can suffer, and we may get sick more frequently. Vitamin D deficiency has been found to make us more susceptible to colds and the flu, as well as infection and autoimmune disorders.

In different sense, every organism needs the heat provided by the sun because then the entire Earth would be too cold for any life to exist. So not every organism needs the energy of the sun for food, but all living things need the heat of the sun to survive.