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Unit 2 Vocab
Unit 2 Vocabulary for Astronomy (Part 2)
| Term | Definition |
|---|---|
| Photosphere | the region of the sun that radiates energy to space; visible surface of the sun |
| Chromosphere | the first layer of the solar atmosphere found directly about the photosphere |
| Corona | the outer weak layer of the solar atmosphere |
| Solar Wind | streams of protons and electrons ejected at high speed from the solar corona |
| Sunspot | a dark spot on the sun, which is cool by contrast to the surrounding photosphere |
| Prominence | a concentration of gases above the solar surface that appears as bright archlike structures |
| Solar Flare | a sudden and tremendous eruption in the solar chromosphere |
| Aurora | a bright display of ever-changing light caused by solar radiation interacting with the upper atmosphere in the region of the poles |
| Nuclear Fusion | the way in which the sun produces energy |
| Constellation | an apparent group of stars orginally named for mythical characters; the sky is presently divided into 88 constellations |
| Binary Star | one of two stars revolving around a common center of mass under their mutual gravitaional attraction |
| Light-year | the distance light travels in a year, about 95. trillion kilometers |
| Apparent magnitude | the brightness of a star when viewed from earth |
| Absolute magnitude | apparent brightness of a star if it were viewed from a distance of 32.6 light-years; used to compare true brightness of stars |
| Main-sequence star | a star that falls into the main sequence category on the H-R diagram |
| Red Giant | a large, cool star of high luminosity |
| Supergiant | a very large, very bright red giant star |
| Cepheid variable | a star whose brightness varies periodically because it expands and contracts; a type of pulsating star |
| Nova | a star that explosively increases in brightness |
| Nebula | a cloud of gas and/or dust in space |
| Hertzsprung-Russell Diagram | a plot of stars according to their absolute magnitudes and temperatures |
| Protostar | a collasping cloud of gas and dust destined to become a star; a developing star not yet hot enough to engage in nuclear fusion |
| Supernova | an exploding star that increases in brightness many thousands of times |
| White Dwarf | a star that has exhausted most or all of its nuclear fuel and has collapsed to a very small size |
| Neutron Star | a star of extremely high density composed entirely of neutrons |
| Pulsar | a variable radio source of small size that emits radio pulses in very regular periods |
| Black Hole | a massive star that has collapsed to such a small volume that its gravity prevents the escape of everything, including light |
| Galaxy | a group of stars, dust, and gases held together by gravity |
| Hubble's Law | a law that states that the galaxies are retreating from the Milkey Way at a speed that is proportional to their distance |
| Big Bang Theory | the theory that proposes that the universe originated as a single mass, which subsequently exploded |
Created by:
DylanMcCarty22
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