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Exploring the Universe

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.The sun gives off tremendous amounts of energy in forms of electromagnetic radiation.The sun's interior consists of the core,the radiation zone,and the convection zone.The suns atmosphere consists of three layers: the photosphere, the chromosphere and the coron.The sun's magnetic field produces striking features on and above it surface ex: sunspots,prominences,and solar flares.The suns mass is more than 300,000 x the mass of earth and its volume is about 1,000,000 x that of earth THE SUN Core- Central region where nuclear fusion occurs. Radiation zone- a region of highly compressed gas. Convection zone- The outer layer or the suns interior Photosphere- 500 kilometers thick and has an average temperature of about 5800 K. Chromosphere- Middle layer of the sun's atmosphere. Corona-The outermost layer of the sun. Solarwinds- a stream of electrically charged particles that flow outwards from the sun. Sunsports- area of gas in the photosphere that are cooler than the surrounding gases. prominences- huge loops of gas that erupt from sunspot region. Solar flare-Sudden release of energy from the sun usually occur near sunspots.

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The sun The Corona

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Stars. A large glowing ball of gas in space. A star generates its energy through nuclear fusion in its core,the coolest star to earth is the sun.Stars are so far apart that astronomers use larger units,including the light-year.various methods have been created just to determine the distance of stars.Due to the telescope,astronomers can now measure the distance of stars with greater accuracy.Stars are classified by color size,brightness other properties are mass and chemical compositions.Astronomers can estimate the diameter and volume of a star by the star's temperature by absolute brightness.Hertzsprung-Russell Diagram or (H-R) are used to estimate the size of stars and their distance to infer how stars change over time Star- Is a large,glowing ball of gas in space which generates through nuclear fusion in its core. Light-Year-Is the distance that light travels in a vacuum in a year, which is about 9.5 trillion kilometers. Parallax- The apparent change in position of an object with respect to a distant background. Apparent brightness- The brightness of a star as it appears from earth. Absolute brightness- is how bright a star really is. Absorption lines- Show where light has been absorbed. H-R diagram- Is a graph of the surface temperature,or,color, and absolute brightness. Main sequence- Astronomers call this diagonal band on the H-R diagram. Supergiants- The very bright stars at the upper right of the H-R diagrams. Giants-Bright stars that are smaller and fainter than supergiant. White Dwarfs-Small dense remains of low or medium mass stars..

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Life Cycles of Stars.A star is formed when a contracting cloud of gas and dust becomes so dense and hot that nuclear fusion begin.A star's mass determines the stars place on the main sequence and how long it will stay.The dwindling supply of fuel in a stars core ultimately leads to the stars death as a white dwarf, neutron star, or black hole Nebula- Is a large cloud of gas and dust spread out over a large volume of space. Protostar- A contracting cloud of gas and dust with enough mass to form a star. Planetary nebula- The dying star surrounded by a glowing cloud of gas. Supernova- An explosion so violent that the dying star becomes more brilliant than an entire galaxy. Neutron star- Is the dense remnant of a high-mass star that has exploded as a supernova. pulsar-A spinning neutron star that appears to gives off strong pulses of radio waves. Black Hole-Is an object whose surface gravity is so great that even electromagnetic waves traveling at the speed of light.

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Rosette Nebula

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Groups of Stars.Astronomers have determined that more than half of gas and dust becomes so dense and hot nuclear fusion begin.There are three basic kinds of star clusters: open,association and globular clusters.Astronomers classify galaxies into four main types, spiral, barred-spiral, elliptical and irregular Constellation- group of stars that appears to form a pattern. Star System- A group of two or more stars that are held together by gravity. Binary system-A star system with two stars. Globular Cluster- A large group of older stars. Galaxy- A huge group of individual stars, star systems, star cluster,dust, and gas bound together by gravity. Spiral Galaxies- Have a bulge of stars at the center, Milky Way. Barred spiral galaxies- Have a bar through the center with the arms extending outward from the bar on either side. Elliptical galaxies- are spherical or oval, with no trace of spiral arms.

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Open Clusters Spiral Galaxies

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The Expanding Universe.The observed red shift in the spectra of galaxies shows that the universe is expanding.Astronomers theorize that the universe came into being at a single moment in a event called the big bang.The existence of cosmic microwave background radiation and the red shift in the spectra of distant galaxies strongly support the big bang theory.Dark matter cannot be seen directly,but its presence can be detected by observing its gravitational effects on visible matter.Dark energy is theorized to be causing the rate of expansion to increase.If the expansion is accelerating, its likely that the universe will expand forever Red shift- the light of galaxies is shifted towards the red wavelengths Hubble's law-the speed at which a galaxy is moving is proportional to its distance from us Big bang Theory- states that the universe began in an instant, billions of years ago, in an enormous explosion Dark Matter- matter that does not give off radiation

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