The observable universe is a ball-shaped region of the universe comprising all matter that can be observedfrom Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. There may be 2 trillion galaxies in the observable universe,[7][8]although that number has recently been estimated at only several hundred billion based on new data from New Horizons.[9][10] Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe has a spherical volume (a ball) centered on the observer. Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth.
 Visualization of the whole observable universe. The scale is such that the fine grains represent collections of large numbers of superclusters. The Virgo Supercluster—home of Milky Way—is marked at the center, but is too small to be seen. | |
| Diameter | 8.8×1026 m or 880 Ym(28.5 Gpc or 93 Gly)[1] |
|---|---|
| Volume | 3.566×1080 m3[2] |
| Mass (ordinary matter) | 1.5×1053 kg[note 1] |
| Density (of total energy) | 9.9×10−27 kg/m3 (equivalent to 6 protons per cubic meter of space)[3] |
| Age | 13.799±0.021 billion years[4] |
| Average temperature | 2.72548 K[5] |
| Contents |
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https://en.wikipedia.org/wiki/Observable_universe
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe.[1] Its presence is implied in a variety of astrophysical observations, including gravitational effects that cannot be explained by accepted theories of gravity unless more matter is present than can be seen. For this reason, most experts think that dark matter is abundant in the universe and that it has had a strong influence on its structure and evolution. Dark matter is called dark because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect or emit electromagnetic radiation, and is therefore difficult to detect.[2]
https://en.wikipedia.org/wiki/Dark_matter
The atmosphere of Earth, commonly known as air, is the layer of gases retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).
By mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.[8] Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air composition, temperature, and atmospheric pressurevary with altitude. Within the atmosphere, air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in Earth's troposphere.[citation needed]
Earth's early atmosphere consisted of gases in the solar nebula, primarily hydrogen. The atmosphere changed significantly over time, affected by many factors such as volcanism, life, and weathering. Recently, human activity has also contributed to atmospheric changes, such as global warming, ozone depletion and acid deposition.
The atmosphere has a mass of about 5.15×1018 kg,[9] three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km (62 mi) or 1.57% of Earth's radius, is often used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric reentry of spacecraft at an altitude of around 120 km (75 mi). Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition.
The study of Earth's atmosphere and its processes is called atmospheric science (aerology), and includes multiple subfields, such as climatology and atmospheric physics. Early pioneers in the field include Léon Teisserenc de Bort and Richard Assmann.[10] The study of historic atmosphere is called paleoclimatology.
https://en.wikipedia.org/wiki/Atmosphere_of_Earth
Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. About 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% is covered with water, mostly by oceans, seas, gulfs, and other salt-water bodies, but also by lakes, rivers, and other freshwater, which together constitute the hydrosphere. Much of Earth's polar regions are covered in ice. Earth's outer layer is divided into several rigid tectonic plates that migrate across the surface over many millions of years, while its interior remains active with a solid iron inner core, a liquid outer core that generates Earth's magnetic field, and a convective mantle that drives plate tectonics.
Earth's atmosphere consists mostly of nitrogen and oxygen. More solar energy is received by tropical regions than polar regions and is redistributed by atmospheric and ocean circulation. Greenhouse gasesalso play an important role in regulating the surface temperature. A region's climate is not only determined by latitude, but also by elevation and proximity to moderating oceans, among other factors. Severe weather, such as tropical cyclones, thunderstorms, and heatwaves, occurs in most areas and greatly impacts life.
Earth's gravity interacts with other objects in space, especially the Moon, which is Earth's only natural satellite. Earth orbits around the Sun in about 365.25 days. Earth's axis of rotation is tilted with respect to its orbital plane, producing seasons on Earth. The gravitational interaction between Earth and the Moon causes tides, stabilizes Earth's orientation on its axis, and gradually slows its rotation. Earth is the densest planet in the Solar System and the largest and most massive of the four rocky planets.
According to radiometric dating estimation and other evidence, Earth formed over 4.5 billion years ago. Within the first billion years of Earth's history, life appeared in the oceans and began to affect Earth's atmosphere and surface, leading to the proliferation of anaerobic and, later, aerobic organisms. Some geological evidence indicates that life may have arisen as early as 4.1 billion years ago. Since then, the combination of Earth's distance from the Sun, physical properties, and geological history have allowed life to evolve and thrive. In the history of life on Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinctions. More than 99% of all species that ever lived on Earth are extinct. Almost 8 billion humans live on Earth and depend on its biosphere and natural resources for their survival. Humans increasingly impact Earth's surface, hydrology, atmospheric processes, and other life.
 The Blue Marble, the most widely used photograph of Earth,[1][2] taken by the Apollo 17 mission in 1972 | |||||||||||||
| Designations | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gaia, Terra, Tellus, the world, the globe | |||||||||||||
| Adjectives | Earthly, terrestrial, terran, tellurian | ||||||||||||
| Orbital characteristics | |||||||||||||
| Epoch J2000[n 1] | |||||||||||||
| Aphelion | 152100000 km (94500000 mi)[n 2] | ||||||||||||
| Perihelion | 147095000 km (91401000 mi)[n 2] | ||||||||||||
| 149598023 km (92955902 mi)[3] | |||||||||||||
| Eccentricity | 0.0167086[3] | ||||||||||||
| 365.256363004 d[4] (31558.1497635 ks) | |||||||||||||
Average orbital speed | 29.78 km/s[5] (107200 km/h; 66600 mph) | ||||||||||||
| 358.617° | |||||||||||||
| Inclination |
| ||||||||||||
| −11.26064°[5] to J2000 ecliptic | |||||||||||||
| 2022-Jan-04[7] | |||||||||||||
| 114.20783°[5] | |||||||||||||
| Satellites |
| ||||||||||||
| Physical characteristics | |||||||||||||
Mean radius | 6371.0 km (3958.8 mi)[9] | ||||||||||||
Equatorialradius | 6378.137 km (3963.191 mi)[10][11] | ||||||||||||
Polar radius | 6356.752 km (3949.903 mi)[12] | ||||||||||||
| Flattening | 1/298.257222101 (ETRS89)[13] | ||||||||||||
| Circumference |
| ||||||||||||
| Volume | 1.08321×1012 km3 (2.59876×1011 cu mi)[5] | ||||||||||||
| Mass | 5.97237×1024 kg (1.31668×1025 lb)[16] (3.0×10−6 M☉) | ||||||||||||
Mean density | 5.514 g/cm3 (0.1992 lb/cu in)[5] | ||||||||||||
| 9.80665 m/s2 (1 g; 32.1740 ft/s2)[17] | |||||||||||||
| 0.3307[18] | |||||||||||||
| 11.186 km/s[5] (40270 km/h; 25020 mph) | |||||||||||||
Sidereal rotation period | |||||||||||||
Equatorial rotation velocity | 0.4651 km/s[20] (1674.4 km/h; 1040.4 mph) | ||||||||||||
| 23.4392811°[4] | |||||||||||||
| Albedo | |||||||||||||
| |||||||||||||
| Atmosphere | |||||||||||||
Surface pressure | 101.325 kPa (at MSL) | ||||||||||||
| Composition by volume | |||||||||||||
https://en.wikipedia.org/wiki/Earth
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in the Earth's outer core: these convection currents are caused by heat escaping from the core, a natural process called a geodynamo. The magnitude of the Earth's magnetic field at its surface ranges from 25 to 65 μT (0.25 to 0.65 gauss).[3] As an approximation, it is represented by a field of a magnetic dipole currently tilted at an angle of about 11 degrees with respect to Earth's rotational axis, as if there were an enormous bar magnetplaced at that angle through the center of the Earth. The North geomagnetic pole actually represents the South pole of the Earth's magnetic field, and conversely the South geomagnetic pole corresponds to the north pole of Earth's magnetic field (because opposite magnetic poles attract and the north end of a magnet, like a compass needle, points toward the Earth's South magnetic field, i.e., the North geomagnetic pole near the Geographic North Pole). As of 2015, the North geomagnetic pole was located on Ellesmere Island, Nunavut, Canada.
While the North and South magnetic poles are usually located near the geographic poles, they slowly and continuously move over geological time scales, but sufficiently slowly for ordinary compasses to remain useful for navigation. However, at irregular intervals averaging several hundred thousand years, the Earth's field reverses and the North and South Magnetic Poles respectively, abruptly switch places. These reversals of the geomagnetic polesleave a record in rocks that are of value to paleomagnetists in calculating geomagnetic fields in the past. Such information in turn is helpful in studying the motions of continents and ocean floors in the process of plate tectonics.
The magnetosphere is the region above the ionosphere that is defined by the extent of the Earth's magnetic field in space. It extends several tens of thousands of kilometres into space, protecting the Earth from the charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer that protects the Earth from the harmful ultraviolet radiation.
https://en.wikipedia.org/wiki/Earth%27s_magnetic_field
The north magnetic pole is a point on the surface of Earth's Northern Hemisphere at which the planet's magnetic fieldpoints vertically downward (in other words, if a magnetic compass needle is allowed to rotate in three dimensions, it will point straight down). There is only one location where this occurs, near (but distinct from) the geographic north pole. The geomagnetic north pole, a related point, is the pole of an ideal dipole model of the Earth's magnetic field that most closely fits the Earth's actual magnetic field.
The north magnetic pole moves over time according to magnetic changes and flux lobe elongation[2] in the Earth's outer core.[3] In 2001, it was determined by the Geological Survey of Canada to lie west of Ellesmere Island in northern Canada at81°18′N 110°48′W.[4] It was situated at 83°06′N 117°48′W in 2005. In 2009, while still situated within the Canadian Arctic at 84°54′N 131°00′W,[5] it was moving toward Russia at between 55 and 60 km (34 and 37 mi) per year.[6] As of 2021, the pole is projected to have moved beyond the Canadian Arctic to 86.400°N 156.786°E.[7][5]
Its southern hemisphere counterpart is the south magnetic pole. Since Earth's magnetic field is not exactly symmetric, the north and south magnetic poles are not antipodal, meaning that a straight line drawn from one to the other does not pass through the geometric center of Earth.
Earth's north and south magnetic poles are also known as magnetic dip poles, with reference to the vertical "dip" of the magnetic field lines at those points.[8]
https://en.wikipedia.org/wiki/North_magnetic_pole
In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field.[1][2] It is created by a star or planet with an active interior dynamo.
In the space environment close to a planetary body, the magnetic field resembles a magnetic dipole. Farther out, field lines can be significantly distorted by the flow of electrically conducting plasma, as emitted from the Sun (i.e., the solar wind) or a nearby star.[3][4] Planets having active magnetospheres, like the Earth, are capable of mitigating or blocking the effects of solar radiation or cosmic radiation, that also protects all living organisms from potentially detrimental and dangerous consequences. This is studied under the specialized scientific subjects of plasma physics, space physics and aeronomy.
https://en.wikipedia.org/wiki/Magnetosphere
https://en.wikipedia.org/wiki/Smith
https://en.wikipedia.org/wiki/Joseph_smith
https://en.wikipedia.org/wiki/Metalsmith
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