The thermosphere is the fourth layer of the atmosphere (if counting from the Earth). It extends from the top of the mesosphere (80 km = 50 miles) to about 700 kilometers (440 miles) above Earth’s surface, where the exosphere begins. The thermosphere is very hot because the Sun’s ultraviolet radiation heats it. This layer contains …
The exosphere (700 to 10,000 km (440 to 6,200 miles)) is the outermost layer of the atmosphere. It extends from the top of the thermosphere to about 10,000 kilometers above Earth’s surface. The exosphere is made up of very thin air heated by the Sun. This layer contains most of the atmosphere’s hydrogen and helium. …
The ocean is a vast and vital source of oxygen for our planet. Every day, billions of tiny ocean plants called phytoplankton produce half of the world’s oxygen supply. Phytoplankton is microscopic, single-celled plants that drift in the sea. They are at the very base of the ocean food chain. Phytoplankton needs sunlight to grow, …
The ocean is a vast and largely untouched ecosystem that covers over 70% of the Earth’s surface. It is home to an immensely diverse range of plant and animal life and provides a crucial human food source. However, the ocean is not immune to the effects of human pollution and is increasingly being contaminated by …
The quick answer to are oceans and seas the same thing? No, oceans and seas are not the same things. The ocean is a large body of water that covers more than 70 percent of the Earth’s surface. Seas are smaller bodies of water found within the ocean or along the coast. More detailed answer …
The study of human evolution is a young science with a history that can be traced back to the late 18th century. But it wasn’t until Charles Darwin’s On the Origin of Species in 1859 that the theory of evolution took hold. In the 150 years since Darwin’s book was published, our understanding of human …
The oldest country in the world is Iran (by date of the earliest known organized government). It was founded in 3200 BCE by the Achaemenid Empire (also called the First Persian Empire). The Achaemenid Empire was a powerful empire that ruled over a large part of the world. The empire was founded by Cyrus the …
Many countries have an abundance of lakes, but which one has the most? With over 563 lakes, Canada has more lakes than any other country. In fact, lakes make up about 9% of Canada’s total surface area. The Great Lakes, which are shared between Canada and the United States, make up the largest group of …
Africa is the world’s second-largest and second-most-populous continent, after Asia. At about 30.3 million km2 (11.7 million square miles), including adjacent islands, it covers 6% of Earth’s total surface area and 20% of its land area. With 1.3 billion people as of 2018, it accounts for about 16% of the world’s human population. The Mediterranean …
Most of Earth’s water is in the oceans. But where did Earth’s water come from? Some of it came from inside the planet. When Earth formed 4.6 billion years ago, it was a hot, molten blob. As it cooled, water vapor escaped from the interior and condensed in the atmosphere. But the oceans hold much …
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