Exam #1
About this set
Created by:
ebincs on September 28, 2009
Subjects:
Astronomy:History, Gravity and Motion, Light and Atoms, Telescopes
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65 terms
Terms | Definitions |
|---|---|
 Scientific notation | a way of representing really large numbers in a seemingly small format |
| Speed of light | speed at which light travels |
| Light year (ly) | distance light travels at constant speed in a year |
| Astronomical unit (AU) | average distance of Earth from the Sun |
| Scientific Method | "Oh, ex con communication": observation, hypothesis, experimentation, conclucsions, communication |
| ecliptic plane | plane which contains the path of Earth around sun; sun, planets, moon and zodiac are ONLY NEAR |
| What distinguished Copernicus' model of the solar system from previous models? How was it wrong? | Heliocentric vs. geocentric solar system; was wrong by stating that motion was uniform and circular |
| Heliocentric | sun centered |
| Geocentric | earth-centered |
| Summer solstice | point on the ecliptic where the Sun is at its northernmost point above the celestial equator, occurring on or near June 21 |
| Winter solstice | point on the ecliptic where the Sun is at its southernmost point below the celestial equator occurring on or near Dec. 21 |
| Vernal equinox | date on which the Sun crosses the celestial equator moving northward occurring on or near March 21 |
| Autumnal equinox | date on which the Sun crosses the celestial equator moving southward occurring on or near September 21 |
| zodiac | 12 constellations that are near the ecliptic and change with the seasonsUpon what conditions does the location of the sunrise on the horizon depend? - Latitude and time of year (ie seasons) |
| What contributions did Tycho Brahe make to astronomy? | Collected extensive data and changed how we observe the heavens; also saw that space was not immutable |
| What contributions did Kepler make? | Made model of what Brahe discovered and his own set of laws Kepler's Laws: I. Planets orbit sun in elipses with the sun in one focus. II. Planets moved faster when near the sun and slower when farther away III. Periods of planet squared is proportional to average distance to sun cubed (p2=a3) |
| Parallax | the apparent shift due to objects position change |
| Arc-second | 1 arc-second = 1/3600° = 1parsec = 3.26ly |
| What astronomical property did Aristarchus of Samos measure? | Calculated the size of the sun and the moon using triangulation |
| What did Eratosthanes measure? | Calculated the radius of the Earth and relative size of it |
| Newton's Laws of Motion | I. Inertia Law, an object at rest stays at rest unless acted upon II. ∑ F = ma, An object accelerates (change in speed or direction) proportional to force and in direction of force and inversely proportional to mass III. F = F, If two objects interact they exert equal and opposite forces on each other |
| Newton's Law of Gravity | G x m1 x m2 / (distance btw centers) squared |
| What are some of the basic properties of matter? | Takes up space, exhibits gravity, inertia, weight, mass, volume and density |
| Which depends on location: mass or weight? | weight |
| The Law of Gravity depends on what two quantities? How do changes in the values affect the force of gravity? | Depends on mass and distance, greater mass with same distance would equal greater gravitational force; greater distance with same mass would equal less gravitational force |
| Semi major axis | represents the average distance from Sun (or one focus) of an orbit |
| Eccentricity | represents the elongation of the orbit or in other words how round the orbit is |
| inclination | the tilt of the orbit with respect to the sun |
| Retrograde motion | backward westward loop traced out by a planet with respect to the fixed stars (mars exhibits retrograde motion) |
| Where do planets move fastest: nearer the sun or farther from the Sun? | According to Kepler's 3rd law, nearer the Sun |
| What are the properties of light and all electro-magnetic radiation? | same speed (3 x105 km/s), waves, electro-magnetic in nature, pass through space |
| What is meant by wave/particle duality in dealing with light? | light exhibits both the properties of waves and particles |
| What are the four fundamental forces of nature? | Ranged from weakest to strongest: I.Gravity II. Electromagnetic: most common III. Strong nuclear: subatomic IV. Weak nuclear: subatomic |
| Spectroscopy | the study of the way in which atoms absorb and emit electromagnetic radiation/ allows determination of chemical composition of stars |
| EM spectrum: Frequency (low to high) | radio, microwave, infrared, visible (red-violet), UV, x-ray, gamma ray |
| EM spectrum: Wavelength (long to short) | radio, microwave, infrared, visible (red-violet), UV, x-ray, gamma ray |
| How are emission and absorption spectra different? How are they the same? How are they used to detect the composition and amount of elements in stars, and the star's motion? | Absorbtion: rainbow background with black lines / Emission: black background with colored lines |
| What two properties of stars and other radiating black bodies does Wien's Law link together? | Temperature and wavelength, ie wavelength at which object's radiation peaks inversely proportional to temperature |
| What happens when electrons change levels? | they absorb or emit light |
| Emitted light in terms of color | white = all colors & black = no color |
| Absorbed light in terms of color | white = no color & black = all colors |
| Understand the meaning and effect of the Doppler shift (blue and red shift) in the spectrum of a star and how it relates to the star's motion toward/away from us | Blue = towards & Red = away |
| What areas of the electro-magnetic spectrum are absorbed by our atmosphere? | Radio, visible and infared not absorbed |
| What telescopes are useful from the ground? | Radio, visible and infared |
| What telescopes are useful from space? | microwave, x-ray, gamma ray, and UV telescopes |
| Telescope Collecting power | how much light telescope collects |
| Telescope Resolving power | how well data collection can be |
| What are refracting telescopes and what are their deficiencies? | Refract light through a lense, and focusing of refracted light creates telescope / Deficiencies: colors absorbed (spectral dispersion), big and expensive, sag and bend max diameter ~1m |
| What are reflecting telescopes and what are their strengths and deficiencies? | reflect all electromagnetic radiation / Strengths: fix the issues of color absorbtion, expensiveness, size and quality of refractor / Deficiencies: flexible (turned into positive by using this to adjust), precise mirror, viewer blocks some light Max size ~6m |
| Are radio telescopes reflectors or refractors? | reflectors |
| How does the process of interferometry help astronomers in viewing the universe? | resolves light interference, ie combines telescopes to give them a higher resolution power |
| How are the basic ways to collect light from telescopes different? | Eye: faint, resolution, limited spectrum / Film: stores info, can allow long exposure, allows sharing and comparing, beyond spectrum of visible light / CCD (charged-coupled device): everything film does, larger spectrum |
| What are problems of using telescopes? | vibration, star tracking and light pollution |
| Atmospheric Scintillation | effect on our viewing of objects in space, caused by the movement and density of the atmosphere, also known as twinkling |
| How big can telescopes get? | Current largest reflector ~10 to 11m & Current largest refractor ~1m |
| Syzygy | alignment of 3 or more bodies |
| Celestial Equator | the equator for the celestial sphere which aligns with the Earth's equator |
| Azimuth | along horizon (relative directions of N, S, E, W) |
| Elevation | how many degrees above horizon in degrees (relative) |
| Declination | latitude-like lines for celestial sphere (absolute) |
| Right Ascension | longitude-like lines for celestial sphere (absolute) |
| Zenith | straight above (relative) |
| Conjunction | when planet is between Earth and sun or behind sun |
| Synodic Period | time between conjunction or opposition |
| light from stars can be used to measure | motion, temp, material, energy output |
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