Information About Earth
EARTH
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the"The Blue Marble" photograph of Earth,
taken from Apollo 17 world or the Blue Planet.[22]
Earth formed approximately 4.54 billion years ago, and life appeared on its surface within its first billion years.[23] Earth's biosphere then significantly altered the atmospheric and other basic physical conditions, which enabled the proliferation of organisms as well as the formation of the ozone layer, which together with Earth's magnetic field blocked harmful solar radiation, and permitted formerly ocean-confined life to move safely to land.[24] The physical properties of the Earth, as well as its geological
history and orbit, have allowed life to persist. Estimates on how much
longer the planet will be able to continue to support life range from 500 million years (myr), to as long as 2.3 billion years (byr).[25][26][27]
Earth's lithosphere is divided into several rigid segments, or tectonic plates, that migrate across the surface over periods of many millions of years.
About 71% of the surface is covered by salt water oceans, with the
remainder consisting of continents and islands which together have many
lakes and other sources of water that contribute to the hydrosphere. Earth's poles are mostly covered with ice that is the solid ice of the Antarctic ice sheet and the sea ice that is the polar ice packs. The planet's interior remains active, with a solid iron inner core, a liquid outer core that generates the magnetic field, and a thick layer of relatively solid mantle.
Earth gravitationally interacts with other objects in space, especially the Sun and the Moon. During one orbit around the Sun, the Earth rotates about its own axis 366.26 times, creating 365.26 solar days, or one sidereal year.[note 7] The Earth's axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planet's surface with a period of one tropical year (365.24 solar days).[28] The Moon is Earth's only natural satellite. It began orbiting the Earth about 4.53 billion years ago (bya). The Moon's gravitational interaction with Earth stimulates ocean tides, stabilizes the axial tilt, and gradually slows the planet's rotation.
The planet is home to millions of species of life, including humans.[29] Both the mineral resources of the planet and the products of the biosphere contribute resources that are used to support a global human population.[30] These inhabitants are grouped into about 200 independent sovereign states, which interact through diplomacy, travel, trade, and military action. Human cultures have developed many views of the planet, including its personification as a planetary deity, its shape as flat, its position as the center of the universe, and in the modern Gaia Principle, as a single, self-regulating organism in its own right.
Earth, our home planet, is the only planet in our solar system known to harbor life. All of the things we need to survive are provided under a thin layer of atmosphere that separates us from the uninhabitable void of space. Earth is made up of complex, interactive systems that are often unpredictable. Air, water, land, and life—including humans—combine forces to create a constantly changing world that we are striving to understand.
Viewing Earth from the unique perspective of space provides the opportunity to see Earth as a whole. Scientists around the world have discovered many things about our planet by working together and sharing their findings.
Some facts are well known. For instance, Earth is the third planet from the sun and the fifth largest in the solar system. Earth's diameter is just a few hundred kilometers larger than that of Venus. The four seasons are a result of Earth's axis of rotation being tilted more than 23 degrees.
Oceans at least 2.5 miles (4 kilometers) deep cover nearly 70 percent of Earth's surface. Fresh water exists in the liquid phase only within a narrow temperature span (32 to 212 degrees Fahrenheit/ 0 to 100 degrees Celsius). This temperature span is especially narrow when contrasted with the full range of temperatures found within the solar system. The presence and distribution of water vapor in the atmosphere is responsible for much of Earth's weather.
Our planet's rapid spin and molten nickel-iron core give rise to a magnetic field, which the solar wind distorts into a teardrop shape. The solar wind is a stream of charged particles continuously ejected from the sun. The magnetic field does not fade off into space, but has definite boundaries. When charged particles from the solar wind become trapped in Earth's magnetic field, they collide with air molecules above our planet's magnetic poles. These air molecules then begin to glow and are known as the aurorae, or the Northern and Southern Lights.
Compared with the billions of other stars in the
universe, the sun is unremarkable. But for Earth and the other planets
that revolve around it, the sun is a powerful center of attention. It
holds the solar system together; pours life-giving light, heat, and
energy on Earth; and generates space weather.
The sun is a big star. At about 864,000 miles (1.4 million kilometers) wide, it could hold 109 planet Earths across its surface. If the sun were a hollow ball, more than a million Earths could stuff inside it. But the sun isn't hollow. It's filled with scorching hot gases that account for more than 99.8 percent of the total mass in the solar system. How hot? The temperature is about 10,000 degrees Fahrenheit (5,500 degrees Celsius) on the surface and more than 28 million degrees Fahrenheit (15.5 million Celsius) at the core.
Deep in the sun's
core, nuclear fusion reactions convert hydrogen to helium, which
generates energy. Particles of light called photons carry this energy
through the sun's spherical shell, called the radiative zone, to the top
layer of the solar interior, the convection zone. There, boiling
motions of gases (like in a lava lamp) transfer the energy to the
surface. This journey takes more than a million years.
The sun's surface, or atmosphere, is divided into three regions: the photosphere, the chromosphere, and the solar corona. The photosphere is the visible surface of the sun and the lowest layer of the atmosphere. Just above the photosphere are the chromosphere and the corona, which also emit visible light but are only seen during a solar eclipse, when the moon passes between the Earth and sun.
Solar Wind and Flares
In addition to light, the sun radiates heat and a steady stream of charged particles known as the solar wind. The wind blows about 280 miles (450 kilometers) a second throughout the solar system. Every so often, a patch of particles will burst from the sun in a solar flare, which can disrupt satellite communications and knock out power on Earth. Flares usually stem from the activity of sunspots, cool regions of the photosphere related to a shifting magnetic field inside the sun.
Like many energy sources, the sun is not forever. It is already about 4.5 billion years old and has used up nearly half of the hydrogen in its core. The sun will continue to burn through the hydrogen for another five billion years or so, and then helium will become its primary fuel. The sun will expand to about a hundred times its current size, swallowing Earth and other planets. It will burn as a red giant for another billion years and then collapse into a white dwarf about the size of planet Earth.
Earth, our home planet, is the only planet in our solar system known to harbor life. All of the things we need to survive are provided under a thin layer of atmosphere that separates us from the uninhabitable void of space. Earth is made up of complex, interactive systems that are often unpredictable. Air, water, land, and life—including humans—combine forces to create a constantly changing world that we are striving to understand.
Viewing Earth from the unique perspective of space provides the opportunity to see Earth as a whole. Scientists around the world have discovered many things about our planet by working together and sharing their findings.
Some facts are well known. For instance, Earth is the third planet from the sun and the fifth largest in the solar system. Earth's diameter is just a few hundred kilometers larger than that of Venus. The four seasons are a result of Earth's axis of rotation being tilted more than 23 degrees.
Oceans at least 2.5 miles (4 kilometers) deep cover nearly 70 percent of Earth's surface. Fresh water exists in the liquid phase only within a narrow temperature span (32 to 212 degrees Fahrenheit/ 0 to 100 degrees Celsius). This temperature span is especially narrow when contrasted with the full range of temperatures found within the solar system. The presence and distribution of water vapor in the atmosphere is responsible for much of Earth's weather.
Protective Atmosphere
Near the surface, an ocean of air that consists of 78 percent nitrogen, 21 percent oxygen, and 1 percent other ingredients envelops us. This atmosphere affects Earth's long-term climate and short-term local weather; shields us from nearly all harmful radiation coming from the sun; and protects us from meteors as well. Satellites have revealed that the upper atmosphere actually swells by day and contracts by night due to solar activity.Our planet's rapid spin and molten nickel-iron core give rise to a magnetic field, which the solar wind distorts into a teardrop shape. The solar wind is a stream of charged particles continuously ejected from the sun. The magnetic field does not fade off into space, but has definite boundaries. When charged particles from the solar wind become trapped in Earth's magnetic field, they collide with air molecules above our planet's magnetic poles. These air molecules then begin to glow and are known as the aurorae, or the Northern and Southern Lights.
SUN Information
Compared with the billions of other stars in the
universe, the sun is unremarkable. But for Earth and the other planets
that revolve around it, the sun is a powerful center of attention. It
holds the solar system together; pours life-giving light, heat, and
energy on Earth; and generates space weather.The sun is a big star. At about 864,000 miles (1.4 million kilometers) wide, it could hold 109 planet Earths across its surface. If the sun were a hollow ball, more than a million Earths could stuff inside it. But the sun isn't hollow. It's filled with scorching hot gases that account for more than 99.8 percent of the total mass in the solar system. How hot? The temperature is about 10,000 degrees Fahrenheit (5,500 degrees Celsius) on the surface and more than 28 million degrees Fahrenheit (15.5 million Celsius) at the core.
Deep in the sun's
core, nuclear fusion reactions convert hydrogen to helium, which
generates energy. Particles of light called photons carry this energy
through the sun's spherical shell, called the radiative zone, to the top
layer of the solar interior, the convection zone. There, boiling
motions of gases (like in a lava lamp) transfer the energy to the
surface. This journey takes more than a million years.The sun's surface, or atmosphere, is divided into three regions: the photosphere, the chromosphere, and the solar corona. The photosphere is the visible surface of the sun and the lowest layer of the atmosphere. Just above the photosphere are the chromosphere and the corona, which also emit visible light but are only seen during a solar eclipse, when the moon passes between the Earth and sun.
Solar Wind and Flares
In addition to light, the sun radiates heat and a steady stream of charged particles known as the solar wind. The wind blows about 280 miles (450 kilometers) a second throughout the solar system. Every so often, a patch of particles will burst from the sun in a solar flare, which can disrupt satellite communications and knock out power on Earth. Flares usually stem from the activity of sunspots, cool regions of the photosphere related to a shifting magnetic field inside the sun.
Like many energy sources, the sun is not forever. It is already about 4.5 billion years old and has used up nearly half of the hydrogen in its core. The sun will continue to burn through the hydrogen for another five billion years or so, and then helium will become its primary fuel. The sun will expand to about a hundred times its current size, swallowing Earth and other planets. It will burn as a red giant for another billion years and then collapse into a white dwarf about the size of planet Earth.
The Moon has many, many different names. It is called Luna by the Romans, Selene and Artemis by the Greeks, and many other names in other mythologies.
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The Moon was first visited by the Soviet spacecraft Luna 2 in 1959. It is the only extraterrestrial body to have been visited by humans. The first landing was on July 20, 1969. The last time we visited the Moon was in December 1972. The Moon is also the only body from which samples have been returned to Earth. In the summer of 1994, the Moon was very extensively mapped by the little spacecraft Clementine. |
The moon is the easiest celestial object to find in the night sky — when it's there. Moon phases and the moon's orbit are a mystery to many. Because it takes 27.3 days both to rotate on its axis and to orbit Earth, the Moon always shows us the same face. We see the Moon because of reflected sunlight. How much of it we see depends on its position in relation to Earth and the Sun.
Though a satellite of Earth, the Moon is bigger than Pluto. Some scientists think of it as a planet (four other moons in our solar system are even bigger), though that viewpoint has never caught on officially. There are various theories about how the Moon was created, but recent evidence indicates it formed when a huge collision tore a chunk of the Earth away.
Physical Characteristics of Earth's Moon
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