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CHCS 8th CH3
CHCS Earth Science Chapter 3
| 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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