CHCS 8th CH3 Word Scramble
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Question | Answer |
gnomon | an instrument used to cast shadows in sunlight |
quadrant | an instrument used to measure a star's position, esp for navigation |
sundial | a gnomon with a numbered dial used to tell time |
refract | to bend or break |
refracting telescopes | uses only lenses to gather light and magnify an image |
Roger Bacon | 1st to use telescopes for navigation and war |
Galileo | 1st to use telescopes for viewing the heavens; used a refracting telescope |
ocular lens | AKA eyepiece lens |
objective lens | the lens that is pointed toward the object being viewed; the diameter of this lens indicates the size of the refracting telescope |
the 3 functions of a telescope | 1) gather light 2) magnify the image 3) bring out the details of the image (resolution) |
resolution | the ability of telescope to bring out the details of an image |
chromatic aberration | color distortion caused by refracting telescopes; makes 'ghosts' around image -- makes image fuzzy; tried to reduce this by making the telescope very long |
reflecting telescopes | invented by Sir Issac Newton; uses a mirror to gather light; eliminates chromatic aberration |
Newtonian Reflector | the image is viewed through the side of the tube |
Cassegrainian Reflector | more compact and easier to use than a Newtonian reflector; the image is viewed through the end like a refracting telescope |
honeycomb mirror | advancement in mirror construction where the mirror is spin cast over a honeycomb shaped base |
segmented mirror | hexagonal (6 sided) mirrors that fit together to make one large mirror |
meniscus mirror | a single piece of glass that is so thin, it requires computer actuators to keep the mirror in the proper shape |
composite telescope | a modern telescope that uses both lenses and a mirror to gather light |
radio telescope | a large "satellite dish" used to collect rays and waves other than visible light; also used as radar to investigate nearby space objects like planets |
2 types of telescope mounts | equatorial and altazimuth |
2 ways to locate stars | constellations or coordinates |
Bayer | assigned Greek letters to the most prominent stars; usually alpha for the brightest, beta for the 2nd brightest, etc... |
celestial equator | the plane of the earth's equator projected into the sky, dividing the heavens into northern and southern halves |
declination (DEC) | a star's angular distance north or south of the celestial equator; + indicates north, - indicates south |
right ascension (RA) | given in hours; gives a stars longitudinal distance east of the Prime Hour Circle |
Prime Hour Circle | the starting line for right ascension |
magnitude | a measure of a star's brightness |
two things that affect a star's brightness | 1) distance from earth 2) absolute magnitude (how much light it is actually giving off) |
the earth's nearest star neighbor | Proxima Centauri; 4.22 light years away from earth |
light year | the distance light travels in a year; 186,000 miles per second; 5.9 trillion miles |
proper motion | a star's motion across the sky as we see it |
radial motion | a star's movement toward or away from earth; + for moving toward us, - for moving away from us |
supergiant | the largest and brightest stars |
white dwarfs | very hot, blue-white stars; extremely dense; near the size of the earth |
eclipsing binaries | two stars that revolve around each other, one dim and one bright, appearing as one star that varies in brightness from night to night; example -- Algol...'the eye of the demon' in the constellation Perseus |
Cepheid variables | a type of star that changes in brightness because it expands and contracts regularly |
nova | "new star"; a star that no one has recorded before, that is visible for a time, and then fades...caused by the star exploding, but the star is not destroyed and may explode again |
supernova | a star that increases in brightness by 20 or more magnitudes, in an explosion that nearly destroys the star |
neutron star | an extremely dense, small, dark star that remains after a supernova explosion |
pulsar | a neutron star that appears to be spinning rapidly and emitting radio waves at regular intervals |
magnetars | neutron stars that have extremely strong rotation magnetic fields |
star cluster | several stars that have the same motions |
open cluster | several stars with the same motions that are relatively far apart |
globular clusters | several stars with the same motions that appear to be a single star; a spherical region of space filled with thousands of closely spaced stars |
galaxy | consists of millions of stars; may be spiral, elliptical, barred spiral, or irregular |
nebula | clouds of gas and dust |
bright nebula | clouds of mostly dust particles that are visible because they reflect light from nearby stars |
planetary nebula | ring shaped nebula |
dark nebula | clouds of gas and dust that do not have nearby source of light; they can be seen because they block light from objects that are behind them |
quasars | areas of space with no nearby objects that emit radio waves; QSO; quasi-stellar objects |
black holes | thought to be unimaginably dense objects with crushing gravity that is so great, not even light can escape; first mentioned by Einstein |
Created by:
mrslisawatson
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