Astronomy Test One
Terms
undefined, object
copy deck
- Polaris
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A: The North Star
A: The end of the handle of the little dipper - Circumpolar
- A: All the stars that never set at a given latitude; all the stars between Polaris and the northern horizon.
- Circumpolar stars at the Nort Pole move how? Are there circumpolar stars at the equator?
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A: move horitzontally
A: no - Explain the daily motions due to the motions of the earth.
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A: earth's rotation causes day and night because it makes the sun appear to follow a diurnal path across the sky
A: Causes constillations and stars to appear to rise in the east and set in the west - Explain annual motions due to the motion of the earth.
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A: the earths revolution around sun--orbit (revolution)
A: takes approx 364 1/4 days
A: different constellations are visible at night during different times of the year.
A: every star rises approx 4 minutes earlier each night than it did the night before - What is the difference between rotation and revolution?
- A: rotation spins around its own axis while revolution spins around another object
- Constellations
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A: a configuration of stars often named after an object, a person, or animal
A: know figures 1-2, 1-3 and 1-4 - Zodiac
- A: A band of 13 constellations around the sky through which the Sun appears to move throughout the year.
- Ecliptic
- A: The annual path of the sun on the celestial sphere; the plane of the earths orbit around the sun.
- Name and define the four (4) phases of the moon.
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A: Quarter Moon--see only half of the moon; high in the sky at sunset; sets at midnight and rises at noon
A: Full Moon--see whole moon (opposite the sun); rises when the sun sets and high in the sky at midnight
A: New Moon--see no moon at all
A: Eclipse--when moon is in shadow of sun - Total Eclipse
- A: moon in its entirity is blocked from sun
- Partial Eclipse
- A: only part of the moon is blocked by the earth
- Annular Eclipse
- A: a ring of the sun around the moon-happens because sun is to far away in orbit for moon to block it out in entirity.
- Solar Eclipse
- block sunlight from getting to the earth; the moon gets in the way; if you are outside the shadow, you don't see the total eclipse
- Lunar Eclipse
- A: the sun, moon, and earth are all lined up with one another
- Why don't eclipses happen every month?
- A: because of the 5 degree tilt of the moon
- What did the Babylonians contribue to the history of astronomy?
- A: provided observations for the Greeks
- What did the Greeks contribute to the History of Astronomy?
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A: Ptolemy wrote book Almagest
A: provided a geocentric (earth centerd) model of the universe - Heliocentric
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A: discovered by Copernicus
A: a sun-centered solar system - What is significant about Tycho Brahe?
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A: he was the last astronomer without a telescope.
A: he provided Kepler with the data needed in order to develop his three laws. - What are Keplers Three (3) Laws of planitary motion?
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A: 1) The orbit of a planet is in the shape of an elipse with the sun at a focus.
A: 2) A line joining a planet and the sun sweeps out equal areas in equal times.
A: 3) The square of a planet's sidercal period around the sun is directly proportional to the cube of the length of its orbits "semimajor axis". - Galileo and his telescope observations.
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A: used a telescope and challenged the conventional wisdom of the motion of objects and the nature of the heavens.
A: Phases of Venus (shows Venus orbits around the sun) and moons of Jupiter (shows Jupiters moons orbit around it not earth) - What are Newtons Three Laws of Motion?
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A: 1) a body remains at rest or moves in a straight line at constant speed unless acted upon by an unbalanced outside force.
A: 2) force=mass x acceleration
A: 3) whenver one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body.
**first two laws apply only to single objects** - Define Newton's universal law of Gravity.
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A: Two bodies attract each other with a force that is inversely proportional to the square of the distance between them.
A: F=G m1m2/r2 - Describe the wave nature of light.
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A: White light-the composite made up of different colors of light
A: Red light- longest wavelength
A: Blue light- shortest wavelenth - Electromagnetic Waves
- A: Einstein showed that light sometimes behaves as particles and sometimes as waves.
- Name different wavelengths, longest to shortest.
- A:longest--Radio, infared, visible, ultraviolet, x-ray, gamma-ray
- Continous Spectrum
- Rainbow
- Emission line Spectrum
- A: A spectrum that contains only bright emission lines.
- Absorption Line Spectrum
- A: dark lines superimposed on a continuous spectrum
- Describe Kirchhoff's three (3) Laws.
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A: 1) You can tell temperature of object by color it emits.
A: 2) Emission lines from low density gass tell chemical composition.
A: 3) Absorption lines show chemical composition of cool lights absorbing the light. - The Doppler Effect
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A: the amount the pitch changes is dependant on how fast the object is moving.
A: Objects moving toward you emit a blue light and those moving away, red.
A: Doesn't work sideways motion, only "radial velocity" (towards/away) - How does temperature effect light?
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A: As an object heats up, it gets brighter because it emits more electromagnetic radiation.
A: The dominant color or wavelength of the emitted radiation changes with temperature. (Cool object emits long wavelengths, hot emits shorter wlengths) - How is chemical composition used in light?
- A: each chemical element has its own unique pattern of spectra lines so chemical composition is determined by the lines in the spectrum.
- Radial Velocity
- A: The speed determinded from the Doppler shift because the motion is along our line of sight or along hte "radius" drawn from Earth to the star.
- What are the reasons for optical telescopes?
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A: 1) light gathering (see fainter objects)
A: 2) Resolution (making a telescope bigger improves resolving power-angular resolution)--limited by atmosphere
A: 3) Magnification - Refractor Telescopes
- A: lens based; chromatic abberation; used by Galileo
- Reflector Telescope
- A: mirror based; spherical aberration-true shape should be parabolic; developed by Newton
- What are some atmosperic effects of telescopes?
- A: seeing only transparent to visible and radio waves; limits angular resolution in practice
- Radio Telescopes
- A:Use a techinique like reflectors to focus radiowaves (like a mirror based optical telescope)
- What are two examples of Radio Telescopes?
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A: Arecibo-largest radio telescope
A: (VLA) Very Large Array- uses interferometry to improve angular resolution - Angular Resolution
- A: let's you see in more detail; limited by the atmostphere
- What is Retrograde Motion and why does it take place?
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A: against the normal motion because the earth moves around the sun more rapidly
A: as it moves along, it appears to stop, go backwards, then forwards again