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Electromagnetic radiation
- Radiation consisting of electromagnetic waves that travel at the speed of light
- e.g. such as visible light, radio waves, and X rays, gamma rays, Ultra Violet rays etc.
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Refracting telescope
A telescope that uses a lens to collect the light from an object
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Reflecting telescopes
A telescope that uses a mirror to collect the light from an object
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Satellite
- An aritificial (human-made) object or vehicle that orbits Earth, the Moon, or other celestial bodies; also, a celestial bosy that orbits another or larger size
- e.g. the Moon is Earth's natural satellite
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oribter
Observatories that orbit other planets.
- They take high-resolution images that are not obtainable from Earth
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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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Star
A celestial body made of hot gases, mainly hydrogen and some helium
e.g. The Sun
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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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Protostar
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
--Nuclear fusion begins when the temperature reaches 10 000 000 degrees Celsius
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photosphere
The surface layer of the Sun
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Sunspot
an area of strong magnetic fields on the photosphere
-- Sun spots occur in 22-yar cycles, peaking in number at intervals of about every 11 years
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Solar wind
A stream of fast- moving charged particles ejected by the Sun into the solar system
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Solar flare
- -Solar flares can occur where there are complex groups of sunspots .
- -Solar flares are an event in which magnetic fields explosively eject intense steams of charged particles(called solar wind) into space
- -When the charged particles from the Sun collide with Earths upper atmosphere auroras can result
- Solar flares
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luminosity
A star's total energy output per second; its power in joules per second (J/s)
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Absolute magnitude
The madnitude of a star that we wouold observe if the star were placed 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 a 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 stars on the H-R diagram that runs siagonally from the upper left ( bright, hot stars ) to the lower right ( dim, cool stars); about 90 percent of stars, including the Sun, are in the 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 the core
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How low-mass stars evolve
They consume their hydrogen slowly, over a period of time. During that time time, they lose significant mass, essentially evaportating. In the end all that remains of them is a very faint white dwarf.
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How intermediate-mass stars evolve
They consume hydrogen faster than low-mass stars, over a period of about 10 billion years. When their hydrogen is used up, the core collapses. As the core contracts, the temperature increases and the outer layer begin to expand.
- the Sun is an intermediate- mass star
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How high-mass stars evolve
they consume their fuel even faster than intermediate stars. As a result, high-mass stars die more quickly and more violently. As heavier elements form by fusion, the star expands into a supergiant
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Black hole
- A tiny patch of space that has no volume, but does have mass.
- The gravity of a black hole is so trong noting can escape it , not even light
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