Some of the oldest evidence of microbial life suggests that it was already widespread on our planet 3.95 billion years ago, Live Science previously reported. What makes Earth special?Įarth is unique because it is the only place in the universe known to host life. Lake Baikal in Russia is the largest and deepest freshwater lake, containing 5,521 cubic miles of water (23,013 cubic km) - a volume approximately equivalent to that of all five North American Great Lakes combined. The Nile is the longest river in the world, winding for 4,132 miles (6,650 km) through northeastern Africa. A crescent-shaped trough at the bottom of the western Pacific Ocean known as the Mariana Trench is the deepest spot on our planet, extending down to 36,037 feet (10,984 m). The tallest point above sea level is the peak of Mount Everest, at 29,032 feet (8,849 meters), according to Britannica). But regions experience different variances in sunlight, so Earth's surface is often broken up into three major climatic zones: the polar regions in the Arctic and Antarctic, which start above or below 66 degrees latitude north or south the middle temperate zones, between 23 and 66 degrees latitude north or south and the tropical regions, between the Tropic of Cancer, at 23 degrees latitude north, and the Tropic of Capricorn, at 23 degrees latitude south, according to the National Oceanic and Atmospheric Administration. What are some characteristics of Earth?Įarth is tilted on its axis by 23.4 degrees, meaning that sunlight falls unevenly on the planet's surface over the course of the year, creating seasonal variation over most of the planet. In 2021, the United Nations announced that parts of the Arctic had reached a new temperature record in June 2020: 100 F (38 C) in the Siberian town of Verkhoyansk. By adding excess carbon dioxide, which traps infrared radiation from the sun, human industry is heating up our planet via global warming. Human activity has a huge effect on climate and weather in Earth's atmosphere. This is followed by the mesosphere, which extends up to 53 miles (85 km) in altitude (this is where meteors burn up), and the thermosphere, which reaches far into space, at least 373 miles (600 km) high. Above that is the stratosphere, where clouds and weather balloons fly, going up to 31 miles (50 km). Most human activity takes place in the lowest atmospheric layer, the troposphere, which extends 5 to 9 miles (8 to 14.5 km) over our heads, NASA says. Our planet's atmosphere is 78% nitrogen, 20% oxygen, 0.9% argon and 0.04% carbon dioxide, plus trace amounts of other gases, according to NASA. The area of Australia is 2.97 million square miles (7.66 million square km), according to the Australian government. North and South America together constitute 16.43 million square miles (42.55 million square km), according to the online encyclopedia Nations Online, while the frozen continent of Antarctica is 5.41 million square miles (14 million square km). The largest continent, which is sometimes known as Afro-Eurasia (though more commonly broken up into Africa, Europe and Asia), has a total area of 32.8 million square miles (84.95 million square km), according to the Encyclopedia of World Geography. In Earth's center is a nickel-iron core that is liquid on the outside, down to 1,400 miles (2,250 km), but is crushed by incredible pressures into a solid form at the lowest depths, according to the USGS.Įarth has several enormous landforms. A common misconception is that all the rock in the mantle is melted into magma in reality, most of it is in a highly viscous form that is so thick that it takes millions of years for its movement to become apparent. The mantle is the next layer down, extending to about 1,800 miles (2,900 km) below Earth's surface. Our planet's crust is a thin outer layer, containing mostly silicate and basaltic rocks, that extends on average around 18 miles (30 km) below the planet's surface, according to the U.S. Earth is composed of many elements, chief among them oxygen, silicon, magnesium, iron, aluminum and nickel, according to Caltech's Infrared Processing and Analysis Center.
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