Chapter #8; Glossary Terms
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Electromagnetic radiation is radiation consisting of electromagnetic waves that Tavel at the speed of light.
, visible light, radio waves and X-rays.
A refracting telescope is a telescope that uses a lens to collect the light from an object.
A reflecting telescope is a telescope that uses a mirror to collect light from a an object.
A satellite is an artificial (human-made) object or vehicle that orbits Earth, the Moon,or other celestial bodies.
It is also a celestial body that orbits another body of larger size. For example,
the Moon is Earth's natural satellite.
of an artificial satellite is the Corot Satellite.
Orbiters or observatories that orbit other celestial bodies.
Solar nebula theory
The solar nebula theory is the theory that describes how stars and planets form from contracting, spinning disks of dust and gas.
A star is a celestial body made of hot gases, mainly hydrogen and some helium.
- Star evolution:
A nebula is a vast cloud of gas and dust, which may be the birthplace of stars and planets.
A protostar is a hot, condensed object at the centre of a Nebula.
Nuclear fusion is the process of energy production in which hydrogen nuclei combine to form helium nuclei.
The photosphere is the surface layered the Sun.
A sunspots an area of strong magnetic fields on the photosphere.
Solar wind is a stream of fast-moving charged particles ejected by the Sun unto the solar system.
Solar flares occur where there are complex sunspots in which magnetic fields explosively eject intense streams of charged particles into space (solar winds).
When they hit earth as solar storms they disrupt telecommunications and damage electronic equipment.
Solar flares can result in shimmering curtains of green and/or red light in the Earth's polar regions called auroras
Importance of the Sun
The solar energy from the Sun drives most processes on Earth that support our daily activities.
Solar energy powers the wind and ocean currents as well as weather.
The Sun emits radiation from across the entire electromagnetic spectrum.
Earth's surface absorbs most of the visible light and emits infrared radiation to the atmosphere.
The process of reflecting and absorbing energy warms Earth's surface.
Luminosity is a star's total energy output per second. it's power is in joules per second.
Absolute magnitude is the magnitude of a star that we would observe if the Starr were 32.6 light-years from Earth.
A spectroscope is 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.
Spectral lines are certain specific wavelengths within a spectrum characterized by lines.
Spectral lines identify specific chemical elements.
Hertzsprung-Russell (H-R) diagram
The Hertzsprung-Russell (H-R) diagram is a graph that compares the properties of stars.
Star colours are graphed on the x-axis and absolute magnitude is graphed on the y-axis.
The main sequence is a narrow band of stars on the H-R diagram that runs diagonally from the upper left (bright, hot stars) to the lower right (dim, cool stars).
About 90 percent os stars, including our Sun, are in the main sequence.
A white dwarf is a small, dim, hot star.
A supernova is a massive explosion in which the entire outer portion of a star is blown off.
A neutron star is a star so dense that only neutrons can exist in its core.
How low-mass stars evolve
Low-mass stars (red dwarfs) have a mass less than the Sun and consume hydrogen for as long as 100 billion years. As they age they slowly become a very faint white dwarf.
While white dwarfs no longer produce energy they are incredibly hot, taking tens of billions of years to cool.
- Scientists theorize that if they do cool down they will become dark embers called black dwarfs.
How intermediate-mass stars evolve
Intermediate-mass stars, such as the Sun consume their hydrogen faster than low-mass stars. When their hydrogen is used up, the core contracts, the temperature increases and the outer layers begin to expand.
The expanded layers are cooler and appear red called a red giant.
How high-mass stars evolve
Stars that are 12 or more solar masses are high-mass stars which consume fuel even faster than intermediate-mass stars. These stars die more quickly and mor violently.
Heavier elements form fusion and the star expands into a supergiant.
Iron forms in the core and the core collapses violently and a shock wave travels though the star.
The outer portion of the star explodes producing a supernova.
A black hole is the remnant of a supernova explosion with a gravitational field so strong that nothing can escape its pull, not even light.
The Sun's Fate
In about 5 billion years the Sun will become a red giant and it will become so large that it's diameter will extend to the current orbit of Mars.
Eventually the layers will disappear into space, and the Sun will become a white dwarf.
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