Earth Quiz

Earth: A Detailed Overview

Earth is the third planet from the Sun and the only known planet with life and habitability.
Earth is an ocean world with 70.8% of its surface covered in liquid surface water.
The polar regions retain most of the other water with large sheets of ice.
The planet's surface is made up of continents and islands, covering 29.2% of the Earth's surface.
Earth has a dynamic atmosphere consisting primarily of nitrogen and oxygen, with water vapor forming clouds.
The greenhouse effect, primarily from carbon dioxide and water vapor, maintains Earth's current average surface temperature of 14.76°C.
Earth has a dense core, generating a magnetosphere that deflects solar winds and cosmic radiation.
Earth's crust consists of several tectonic plates that interact to produce mountain ranges, volcanoes, and earthquakes.
Earth is the largest and most massive of the four rocky planets and is rounded into an ellipsoid with a circumference of about 40,000 km.
Earth orbits the Sun and takes a year to complete one revolution while rotating around its own axis in about 23 hours and 56 minutes.
Earth's axis of rotation is tilted, producing seasons, and is orbited by one permanent natural satellite, the Moon.
Chemical reactions led to the first self-replicating molecules about four billion years ago, and life evolved to form complex cells called eukaryotes, which led to the evolution of humans.Earth's Structure and Composition
Earth's surface is composed of land and water, with the interconnected ocean covering 70.8% of the surface area.
The ocean floor comprises various features, including abyssal plains, continental shelves, and mid-ocean ridges.
The land surface varies in elevation, from the low point of the Dead Sea to the highest point of Mount Everest.
Earth's land is divided into four continental landmasses: Africa-Eurasia, America, Antarctica, and Australia.
Earth's interior is divided into layers, with the outer layer being a silicate solid crust and the innermost layer being a solid iron inner core.
Earth's crust is divided into tectonic plates that move relative to each other at convergent, divergent, and transform boundaries.
Earth's major heat-producing isotopes are potassium-40, uranium-238, and thorium-232.
Earth's magnetic field is generated in the core and extends outward, with the magnetic poles drifting and periodically changing alignment.
The extent of Earth's magnetic field defines the magnetosphere, which deflects ions and electrons of the solar wind.
Earth's gravity field varies due to differences in topography, geology, and tectonic structure, resulting in gravity anomalies.
Earth's composition is primarily iron, oxygen, silicon, magnesium, and sulfur, with the core being composed primarily of iron.
Earth's mass is approximately 5.97×10^24 kg, and its density is the highest among the Solar System's planetary-sized objects.Overview of Earth's Physical Characteristics
Earth's rotation period relative to the Sun is 86,400 seconds, while its rotation period relative to the fixed stars is 86,164.0989 seconds.
Earth orbits the Sun every 365.2564 mean solar days, with an average orbital speed of 29.78 km/s.
The Moon is Earth's largest natural satellite, with a diameter about one-quarter of Earth's, and its gravitational attraction causes tides on Earth.
Earth's hydrosphere consists of water in the atmosphere, on land, and in its global ocean, which covers an area of 361.8 million km2 with a mean depth of 3,682 m.
Most of Earth's water is saline, with the remaining 2.5% being fresh water, of which about 68.7% is present as ice in ice caps and glaciers.
Earth's atmosphere is composed of 78.084% nitrogen, 20.946% oxygen, and trace amounts of other gaseous molecules, with a water vapor content that averages about 1%.
The atmospheric pressure at Earth's sea level averages 101.325 kPa, and the height of the troposphere varies with latitude.
Earth's axial tilt of approximately 23.44 degrees causes seasonal changes in climate, with summer occurring when the Tropic of Cancer is facing the Sun in the Northern Hemisphere, and winter occurring when the Tropic of Capricorn faces the Sun in the Southern Hemisphere.
Earth's axial tilt undergoes nutation and precession, with the poles migrating a few meters across Earth's surface, and Earth's rotational velocity varies in length-of-day variation.
Earth is situated in the Milky Way and orbits about 28,000 light-years from its center, about 20 light-years above the galactic plane in the Orion Arm.
Earth's Hill sphere, or sphere of gravitational influence, is about 1.5 million km in radius, and objects must orbit Earth within this radius to avoid becoming unbound by the gravitational perturbation of the Sun.
Earth's changing distance from the Sun causes cyclical patterns known as Milankovitch cycles, and the abundance of water on Earth's surface distinguishes it from other planets in the Solar System.Overview of Earth: Atmosphere, Weather, Life, Human Impact, and Cultural Views
Earth has a primarily nitrogen-oxygen atmosphere that enabled the proliferation of aerobic organisms and the formation of the ozone layer, which blocks ultraviolet solar radiation and permits life on land.
The atmosphere also transports water vapor, provides useful gases, moderates temperature through the greenhouse effect, and causes small meteors to burn up before they strike the surface.
Earth's surface can be divided into specific latitudinal belts of approximately homogeneous climate, ranging from the equator to the polar regions, with precipitation patterns varying widely.
The upper atmosphere is divided into the stratosphere, mesosphere, and thermosphere, each with a different lapse rate, and the exosphere thins out into the magnetosphere.
Earth is the only known place that was and has been habitable for life, developing in Earth's early bodies of water and shaping many particular ecosystems on Earth, eventually forming an overarching biosphere.
Earth's life has over time greatly diversified, allowing the biosphere to have different biomes, which are inhabited by comparatively similar plants and animals.
Human population has grown exponentially since the 19th century to seven billion in the early 2010s, and is projected to peak at around ten billion in the second half of the 21st century, with most of the growth expected to take place in sub-Saharan Africa.
Human activities have impacted Earth's environments, increasing the amount of greenhouse gases in the atmosphere, altering Earth's energy budget and climate, and crossing five of the nine identified planetary boundaries.
Earth has resources that have been exploited by humans, including non-renewable resources and biological products for humans, such as food, wood, pharmaceuticals, and oxygen.
Human cultures have developed many views of the planet, including the standard astronomical symbols of Earth, personification as a deity, creation myths, and the Gaia hypothesis.
Images of Earth taken from space have altered the way people view the planet, emphasizing its beauty, uniqueness, and apparent fragility, causing a realization of the scope of effects from human activity on Earth's environment.
Enabled by science, particularly Earth observation, humans have started to take action on environmental issues globally, acknowledging the impact of humans and the interconnectedness of Earth's environments, resulting in several culturally transformative shifts in people's view of the planet.