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9.1The Sun

Characteristics of the Sun

The Sun is a 1,390,000 km in diameter.

The temperature of the surface is 5000° C and the center core at 15,600,000° C.

The energy released from the fusion reactions near the Sun's core is in the form of very high frequency electromagnetic waves called gamma rays.

Structure of the Sun

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The core is the center of the thermonuclear fusion reactions which power the sun. The matter in the core consists of plasma at temperatures of about 15,000,000 K. The density of the core is about 160,000 kg/m^3. If we could see the core, it would be 10^13 times brighter than the surface we now see.The radiative zone surrounds the core. It helps to maintain the high temperatures needed to sustain the nuclear fusion. The nuclei in it absorbed the gamma protons produced in core’s fusion.The convective zone surrounds the radiative zone and is the outermost layer of the interior. It is cooler and less dense than the radiative zone. It derives its name from the convection processes which bring the heat to the surface of the sun.

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The photosphere produces the visible light we see and generally considered to be the surface of the sun. It is one of the coolest layers of the sun at a meager 6000 K, and it has a density of about 10^-6 kg/m^3. Large magnetic disturbances sometimes break through the photosphere and cause sunspots, which are cooler, darker regions.The chromosphere is considered to be part of the solar atmosphere, along with the photosphere. It takes its name from the red light it shines, though this light is much dimmer than that of the photosphere. At 4300 K, it is cooler than the photosphere at its base, but it can get up to 50,000 K in its outer reaches. It causes various events, such as filaments, plage, spicules, and flares The corona is the outermost layer of the sun. It is divided into the inner corona and the outer corona. The inner corona is a wispy halo surrounding the sun. It cannot be seen except during a total solar eclipse. The outer corona is the outermost atmosphere of the sun, and it includes much of the solar system.

Phenomena on the Sun Surface

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Sunspot

Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature. They usually appear as pairs, with each sunspot having the opposite magnetic pole to the other.

Prominences

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A prominence is a large, bright, gaseous feature extending outward from the Sun's surface, often in a loop shape. Prominences are anchored to the Sun's surface in the photosphere, and extend outwards into the Sun's corona. While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromosphere. The prominence plasma is typically a hundred times cooler and denser than the coronal plasma. Prominence may persist in the corona for several weeks or months. Some prominences break apart and may then give rise to coronal mass ejections. Scientists are currently researching how and why prominences are formed.

Solar Wind

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The solar wind is a stream of fun (a plasma) released from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. These particles can escape the Sun's gravity because of their high kinetic energy and the high temperature of the corona.

The solar wind flows outward supersonically to great distances, filling a region known as the heliosphere, an enormous bubble-like volume surrounded by the interstellar medium. Other related phenomena include geomagnetic storms that can knock out power grids on Earth, the aurora (northern and southern lights), and the plasma tails of comets that always point away from the Sun.

Solar Flare

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A solar flare is a sudden brightening observed over the Sun's surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy (about a sixth of the total energy output of the Sun each second or 160,000,000,000 megatons of TNT equivalent, over 25,000 times more energy than released from the impact of Comet Shoemaker–Levy 9 with Jupiter).

They are often, but not always, followed by a colossal coronal mass ejection also known as a CME.[1] The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach Earth a day or two after the event.[2] The term is also used to refer to similar phenomena in other stars, where the term stellar flare applies.

Solar Flare

Size of earth

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Aurora

An aurora (plural: auroras or aurorae; from the Latin word aurora, "sunrise" is a natural light display in the sky particularly in the high latitude (Arctic and Antarctic) regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere (thermosphere).

The charged particles originate in the magnetosphere and solar wind and, on Earth, are directed by the Earth's magnetic field into the atmosphere. Most auroras occur in a band known as the auroral zone, which is typically 3° to 6° wide in latitude and observed at 10° to 20° from the geomagnetic poles at all local times (or longitudes). During a geomagnetic storm, the auroral zone expands to lower latitudes.

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Generation of solar energy

Solar Energy Generating Systems (SEGS) in California, with the combined capacity from three separate locations at 354 megawatts (MW, 474,700 hp), is the largest solar thermal energy generating facility in the world. It consists of nine solar power plants in California's Mojave Desert, where insolation is among the best available in the United States. SEGS I–II (44 MW) are located at Daggett (34°51 45″N 116°49 45″W), SEGS III–VII (150 MW) are ′ ′installed at Kramer Junction, and SEGS VIII–IX (160 MW) are placed at Harper Lake (35°02 N 117°21 W). Next Era Energy Resources ′ ′operates and partially owns the plants located at Kramer Junction and Harper Lake.

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9.2The Stars and Galaxies In the

UniverseDefinition of a star

Star is a fixed luminous point in the night sky which is a large, remote incandescent body like the sun.True stars were formerly known as the fixed stars, to distinguish them from the planets or wandering stars. They are gaseous spheres consisting primarily of hydrogen and helium, there being an equilibrium between the compressional force of gravity and the outward pressure of radiation resulting from internal thermonuclear fusion reactions. Some six thousand stars are visible to the naked eye, but there are actually more than a hundred thousand million in our own Galaxy, while billions of other galaxies are known.

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Various types of star

Protostar

T Tauri Star

Main Sequence Star

Red Giant Star

White Dwarf Star

Red Dwarf Stars

Neutron Stars

Supergiant Stars

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Formation of star

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Death of Stars

Stars expand as they grow old. As their core runs out of hydrogen and then helium, the core contacts and the outer layers expand, cool, and become less bright. This is a red giant or a red super giant (depending on the initial mass of the star). It will eventually collapse and explode. A star's life span and eventual fate are determined by the original mass of the star.

Life span:The most massive stars have the shortest lives. Stars that are 25 to 50 times that of the Sun live for only a few million years. They die so quickly because they burn massive amounts of nuclear fuel.

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GalaxiesOther galaxies have elliptical shapes, and a few have unusual shapes like toothpicks or rings. The Hubble Ultra Deep Field(HUDF) shows this diversity. Hubble observed a tiny patch of sky (one-tenth the diameter of the moon) for one million seconds (11.6 days) and found approximately 10,000 galaxies, of all sizes, shapes, and colors. From the ground, we see very little in this spot, which is in the constellation

The Milky WayOur galaxy, the Milky Way, is typical: it has hundreds of billions of stars, enough gas and dust to make billions more stars, and at least ten times as much dark matter as all the stars and gas put together. And it’s all held together by gravity.Like more than two-thirds of the known galaxies, the Milky Way has a spiral shape. At the center of the spiral, a lot of energy and, occasionally, vivid flares. are being generated.

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9.2The Universe As A Gift From God

As we know, the universe is a gift from our Merciful God, Allah S.W.T. He created creatures such as Sun, stars, planets including the Earth, galaxies and all things in the universe for us to use them in the right way besides taking the benefits in our everyday life. Without all of the creatures, how can human survive? We can’t even live in the world. That’s why, Allah S.W.T had all of this since . he is The Most . Allah has tell us about the universe in The Holy Al-Quran, surah Al-Mulk verse 6, ‘And indeed, we have beautified the nearest heaven (the earth) with the stars and we make it (the stars) as stoning the devil tools and we provide for them the torment of the blazing Fire’. So, as human, we should appreciate and take care about the nature of the universe as He want us to do.

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10.1Development In The Field Of Astronomy And Space Exploration-Development in astronomy

Early astronomers

Sir Isaac Newton(1643-1727)Woolsthorpe-by-Colsterworth, Lincolnshire,England

Nicolaus Copernicus (1473-1543Thorn, Poland

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Modern astronomers

Contributions of astronomers

Nancy Grace Roman

Dr. Elezabeth Roemer

Dr. Heidi Hammel

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Charles Messier -create one of the most famous catalogues of deep sky objects including nebulae and galaxies. - successful in discovering thirteen comets.

Ptolemy -He Preserved the Greek astronomer Hipparchus’ star catalogue, which he included in his astronomical magnum opus, Amalgest. He also included in his work a set of tables (known almost comically as the Handy Tables), which made it much easier to calculate the positions of the planets, the sun and the moon, the rising and setting of the stars, and the dates of lunar and solar eclipses.

Copernicus- He is credited as the first astronomer to put forward a comprehensive heliocentric version of the solar system. -The idea that the Earth revolved around the sun went directly against the teachings of the church. For his courageous introduction of the true nature of the solar system to European scholars he is remembered as a monument to the truth in a society largely unwilling to accept it.

-Development in space exploration Space Exploration

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Space exploration is the ongoing discovery and exploration of celestial structures in outer space by means of continuously evolving and growing space technology. While the study of space is carried out mainly by astronomers with telescopes, the physical exploration of space is conducted both by unmanned robotic probes and human spaceflight.

Rockets

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Spacecraft

Artificial satellites

A rocket is a missile, spacecraft, aircraft or other vehicle that obtains thrust from a rocket engine. Rocket

engine. Rocket engines push rockets forward simply by throwing their exhaust backwards extrexhaust is formed

entirely frompropellants carried within the rocket before use.[1] Rocket engines work by action and reactionemely fast.

A spacecraft (or spaceship) is a vehicle, vessel or machine designed to fly in outer space. Spacecraft are

used for a variety of purposes, including communications, earth observation, meteorology,

navigation, planetary exploration and transportation of humans and cargo.

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A satellite is an object that orbits another object. In space, satellites may be made by man, or they may be natural.

The moon is a natural satellite that orbits the Earth. Most man-made satellites also orbit the Earth, but some orbit other

planets, such as Saturn, Venus or Mars, or the moon.

Satellites

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Space probes

Space station

In the context of spaceflight, a satellite is an artificial object which has been

intentionally placed into orbit. Such objects are sometimes called artificial satellites to

distinguish them from natural satellites such as the Moon.

A space probe is a unmanned spacecraft that leaves Earth orbit and explores space.

It may approach the Moon; enter interplanetary space; flyby, orbit or land on

other planetary bodies; or approach interstellar space. Space probes are a form

of robotic spacecraft.

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Space shuttle

Space telescope

A space station (or orbital station) is a spacecraft capable of supporting a crew, which is designed to remain in space (most commonly in low Earth orbit) for an extended period of time and for other spacecraft to dock.

The Space Shuttle was a crewed, partially reusable low Earth orbital spacecraft operated by the U.S. National Aeronautics and Space Administration (NASA). Its official program name was Space Transportation System, taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development.

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The Hubble Space Telescope (HST) is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation.[7] A 2.4-meter (7.9 ft) aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared spectra. The telescope is named after the astronomer Edwin Hubble.Hubble's orbit outside the distortion of Earth's atmosphere allows it to take extremely high-resolution images with almost no backgroundlight. Hubble's Deep Field has recorded some of the most detailed visible-light images ever, allowing a deep view into space and time. Many Hubble observations have led to breakthroughs in astrophysics, such as accurately determining the rate of expansion of the universe.

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-Application of technology related to space exploration and astronomy

Communication satellites

A communications satellite or comsat is an artificial satellite sent to space for the purpose of telecommunications. Modern communications satellites use a variety of orbits including geostationary orbits, Molniya orbits, elliptical orbits and low (polar and non-polar) Earth orbits.For fixed (point-to-point) services, communications satellites provide a microwave radio relay technology complementary to that of communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and hand-held terminals, and for TV and radiobroadcasting.

Navigation satellites

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Indian Regional Navigation Satellite System (IRNSS) IRNSS is an independent regional navigation satellite system being developed by India. It is designed to provide accurate position information service to users in India as well as the

region extending up to 1500 km from its boundary, which is its primary service area. IRNSS will provide two types of services,

namely, Standard Positioning Service (SPS) and Restricted Service (RS) and is expected to provide a position accuracy of

better than 20 m in the primary service area.

Military satellites

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A military satellite is an artificial satellite used for a military purpose. The most common missions

are intelligence gathering, navigation and military communications. The first military satellites were photographic reconnaissance missions. Some attempts were made to develop

satellite based weapons but this work was halted in 1967 following the ratification of international treaties banning the

deployment of weapons of mass destruction in orbit. As of 2013, there are 950 satellites of all types in Earth orbit. It is not possible to identify the exact number of these that are military satellites partly due to secrecy and partly due to dual purpose

missions such as GPS satellites that serve both civilian and military purposes.

Weather satellites

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The weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be polar orbiting, covering the entire Earth asynchronously, or geostationary, hovering over the same spot on the equator. Meteorological satellites see more than clouds and cloud systems. City lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents, energy flows, etc., and other types of environmental information are collected using weather satellites. Weather satellite images helped in monitoring the volcanic ash cloud from Mount St. Helens and activity from other volcanoes such as Mount Etna. Smoke from fires in the western United States such as Colorado and Utah have also been monitored.

Environmental satellites

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The Geostationary Satellite system (GOES), operated by the United States National Environmental Satellite, Data, and Information Service (NESDIS), supports weather forecasting, severe storm tracking, and meteorology research. Spacecraft and ground-based elements of the system work together to provide a continuous stream of environmental data. The National Weather Service (NWS) uses the GOES system for its United States weather monitoring and forecasting operations, and scientific researchers use the data to better understand land, atmosphere, ocean, and climate interactions.The GOES system uses geosynchronous satellites which—since the launch of SMS-1 in 1974—have been a basic element of U.S. weather monitoring and forecasting.

Remote sensing

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Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object and thus in contrast to in observation. Reflected sunlight is the most common source of radiation measured by passive sensors. Examples of passive remote sensors include film photography, infra-red, charge-coupled devices, and radiometers. Active collection, on the other hand, emits energy in order to scan objects and areas whereupon a

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sensor then detects and measures the radiation that is reflected or backscattered from the target. RADAR and LiDAR are examples of active remote sensing where the time delay between emission and return is measured, establishing the location, speed and direction of an object (sunlight) when information is merely recorded.

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