Earth Quiz

Earth: The Third Planet from the Sun and the Only Known Habitable Place in the Universe

• Earth is the third planet from the Sun and the only known place in the universe where life has originated and found habitability.

• Earth is an ocean world, with over 70.8% of its surface covered by liquid surface water, and its polar regions retaining most of the other water in the form of large sheets of ice covering oceans and land.

• Earth's land consists of continents and islands, extending over 29.2% of the Earth and is widely covered by vegetation.

• Earth's crust consists of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes.

• Earth has an atmosphere composed mainly of nitrogen and oxygen, with water vapor acting as a greenhouse gas, creating the conditions for liquid surface water and water vapor to persist via the capturing of energy from the Sun's light.

• Earth is the densest planet in the Solar System, and the largest and most massive of the four rocky planets.

• Earth is about eight light-minutes away from the Sun and orbits it, taking a year (about 365.25 days) to complete one revolution.

• Earth's axis of rotation is tilted with respect to the perpendicular to its orbital plane around the Sun, producing seasons.

• Earth is orbited by one permanent natural satellite, the Moon, which orbits Earth at 384,400 km and is roughly a quarter as wide as Earth.

• Earth formed 4.5 billion years ago from gas in the early Solar System and the ocean formed during the first billion years of Earth's history, followed by the development of life within it.

• Humans emerged 300,000 years ago and have reached a population of 8 billion today, depending on Earth's biosphere and natural resources for their survival.

• Earth's future is tied to that of the Sun, which will evolve to become a red giant in about 5 billion years, and Earth's fate is less clear, either moving to an orbit 1.7 AU from the Sun or being vaporized by entering the Sun's atmosphere.Earth's Surface, Internal Structure, Tectonic Plates, and Magnetic Field

• Earth's shape is an oblate spheroid, with the equatorial diameter larger than the polar diameter.

• Earth's surface is divided into two hemispheres, polar Northern and Southern hemispheres, or continental Eastern and Western hemispheres.

• The world ocean is commonly divided into five oceans, the Pacific, Atlantic, Indian, Southern, and Arctic oceans, from largest to smallest.

• Earth's land is 29.2% of Earth's surface area, consisting of four continental landmasses, Africa-Eurasia, America, Antarctica, and Australia.

• Earth's lithosphere is divided into tectonic plates, which move relative to each other at convergent, divergent, and transform boundaries.

• Earth's interior is divided into layers by their chemical or physical properties, including the crust, mantle, outer core, and inner core.

• Potassium-40, uranium-238, and thorium-232 are the major heat-producing isotopes within Earth.

• The mean heat loss from Earth is 87 mW m−2, for a global heat loss of 4.42×1013 W.

• The gravity of Earth is approximately 9.8 m/s2 near Earth's surface, with local and broad regional differences known as gravity anomalies.

• Earth's magnetic field is generated in the core and extends outwards through the mantle and up to Earth's surface.

• The poles of the magnetic field drift and periodically change alignment, causing secular variation and field reversals at irregular intervals.

• The extent of Earth's magnetic field in space defines the magnetosphere, which deflects ions and electrons of the solar wind.Key Points about Earth

• Earth's magnetosphere contains charged particles, with the plasmasphere, ring current, and Van Allen radiation belts being defined by different energy levels of particles.

• Earth's rotation period relative to the Sun is 86,400 seconds, but it's slightly longer due to tidal deceleration, and 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 about 29.78 km/s.

• The Moon is Earth's largest natural satellite, with a diameter about one-quarter of Earth's. Its gravitational attraction causes tides on Earth, and it recedes from Earth at the rate of approximately 38 mm/a (1.5 in/year).

• Earth's hydrosphere consists of Earth's global ocean, water in the atmosphere and on land, including clouds, inland seas, lakes, rivers, and underground waters. The oceans cover an area of 361.8 million km2 with a mean depth of 3,682 m.

• Most of the water on Earth is saline, with only 2.5% being freshwater, and most of that is present as ice in ice caps and glaciers.

• Earth's axial tilt of approximately 23.439281° 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 is facing the Sun in the Southern Hemisphere.

• Earth's co-orbital asteroids population consists of quasi-satellites, objects with a horseshoe orbit and trojans, and there are currently over 4,550 operational, human-made satellites orbiting Earth.

• The abundance of water, particularly liquid water, on Earth's surface is a unique feature that distinguishes it from other planets in the Solar System.Earth: A Summary of Its Atmosphere, Weather, Climate, Life, Human Geography, and Environmental Impact

Atmosphere:

• Earth's atmosphere is composed of nitrogen, oxygen, argon, and trace amounts of other gases.
• The atmosphere is vital for life on Earth, as it moderates temperature and protects from harmful solar radiation.
• The atmosphere is divided into different layers, each with its own characteristics.

Weather and Climate:

• Earth's weather and climate are driven by atmospheric circulation, ocean currents, and energy from the Sun.
• Earth's climate can be divided into different latitudinal belts, each with its own distinct climate.
• The Köppen climate classification system rates regions based on observed temperature and precipitation.

Life on Earth:

• Earth is the only known place that is and has been habitable for life.
• Earth's life has greatly impacted Earth's atmosphere and surface over long periods of time.
• Earth's species diversity and biomass reaches a peak in shallow waters and forests.

Human Geography:

• Human population has grown exponentially since the 19th century and is projected to peak at around ten billion in the second half of the 21st century.
• Human population density varies greatly around the world, with the majority living in south to eastern Asia and the Northern Hemisphere.
• Earth's land has been territorially claimed since the 19th century by sovereign states separated by political borders.

Environmental Impact:

• Human activities have impacted Earth's environments, causing global warming and the crossing of planetary boundaries.
• It is possible to provide all basic physical needs globally within sustainable levels of resource use.
• Cultural and historical viewpoints have shaped people's views of the planet, with images of Earth taken from space altering people's perception of the planet.