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Electromagnetic Radiation
radiation consisting of electromagnetic waves that travel faster than the speed of light
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Refracting Telescope
a telescope that uses a lens to collect the light from an object
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Reflecting Telescope
a telescope that uses a mirror to collect the light from an object
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Satellite
An artificial (human made) object or vehicle that orbits Earth, the Moon, or other celestial bodies; also, a celestial body that orbits another body of larger size
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Orbiters
observatories that orbit other celestial objects
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Star
A celestial body made of hot gases, mainly hydrogen and some helium
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Protostar
A hot, condensed object at the centre of a nebula
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Nuclear Fusion
The process of energy production in which hydrogen nuclei combine to form helium nuclei
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Photosphere
The surface layer of the Sun
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Sunspot
A celestial body made of hot gases, mainly hydrogen and some helium
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Solar Wind
A stream a fast-moving charged particles ejected by the Sun into the solar system
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Luminosity
A star's total energy output per seconds;its power in joules per second
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Absolute magnitude
The magnitude of a star that we would observe if the star was 32.6 light years from Earth
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Spectroscope
An optical instrument that produces a spectrum from a narrow beam of light, and usually projects the spectrum onto a photographic plate or digital detector
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Spectral Lines
certain specific wavelengths within a spectrum characterized by lines; spectral lines identify specific chemical elements
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Hertzsprung-Russell (H-R) diagram
a graph that compares the properties of stars
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Main Sequence
a narrow band of star on the H-R diagram that runs diagonally from the upper left (bright, hot stars) the the lower right (dim, cool stars); about 90 Percent of stars, including the Sun are main sequence
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White Dwarf
A small, dim, hot star
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Supernova
A massive explosion in which the entire outer portion of a star is blown off
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Neutron Star
A star so dense that only neutrons can exist in its core
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Black Hole
The remnant of a supernova explosion with a gravitational field so strong that nothing can escape its pull
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Solar Nebula Theory
The theory that describes how stars and planets form from contracting, spinning disks of gas and dust
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Nebula
A vast cloud of gas and dust, which may be the birthplace of stars and planets
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How low-mass stars evolve
They consume their hydrogen slowly over a period that may be as long as 10 billion years. During that time they loose their significant mass, essentially evaporating. In the end all that remains is a very faint white dwarf. It could take tens of billions of years for a white dwarf to cool down and when they do they will become nothing more than dark embers called black dwarfs
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How intermediate-mass stars evolve
They consume there hydrogen faster than low-mass stars, over a period of about 10 billion years. When their hydrogen is used up their core collapses. As the core contracts the temperature increases and the outer layers begin to expand. The expanded layers are cooler and appear red. At this phase the star is called a red giant. It will be come so large its diameter will out to the orbit of Mars. Eventually the layers will disappear and the Sun will become a white dwarf
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How high-mass stars evolve
Stars that are 12 or more solar masses are high-mass stars. These stars consume their fuel even faster than intermediate stars. As a result, high-mass stars die more quickly and more violently. The core will heat up and the heavier elements form by fusion and the star expands into a supergiant. Eventually Iron forms in its core. Since iron cannot release energy through fusion. the core collapses violent, and a shock wave travels through the star. The outer portion of the star explodes, producing a supernova. A supernova can be millions of times brighter than the original star.
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