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Flashcards in Final Deck (34)
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most associated with the ancient Greek world view (geocentric universe)



rejected the geocentric world view



accurately determined the size of the earth



wrote Almgest



it explained astronomical movements better and was simpler than the geocentric model

Heliocentric model


held the heliocentric worldview



last astronomer without a telescope; provided Kepler with the data needed in order to develop his three laws of motion

Tycho Brahe


Three Laws of Motion; his laws don't qualify as modern astronomical discoveries because they are descriptive only and don't take gravity into account

J. Kepler


the shape of the orbit of the planets is an ellipse and the Sun isn’t in the center, but at a foci of the ellipse orbit; the orbit of the earth and other planets (some are more dramatically elliptical than others) is just slightly off form being a circle, so his measurements had to be very precise - this is very impressive

Law of Ellipses


he closer the planet is to the sun in its orbit, the faster it is moving; states that an imaginary line between a planet and the sun sweeps out an area as the planet orbits such that if 3 time intervals are shown are of equal length, then the areas A, B, and C will be equal

the Law of Equal Areas


he farther out the orbit is, the longer it takes for the planet to orbit; to find the orbit time use p^2 = a^3 where p is years and a is astronomical units

The Third Law


used a telescope and challenged the conventional wisdom of the motion of objects and the nature of the heavens; his telescope observations are: the Phases of Venus, the moons of Jupiter, sunspots, and mountains on the moon



three laws of motion and the law of universal gravity



a body at rest or moving in a straight line at a constant velocity will continue in that manner unless acted by a net outside force

Newton's First Law


F = mass x acceleration; acceleration is change in velocity; change in velocity = either speed up or slow down in the same direction or change direction

Newton's Second Law


Law of Reciprocal Actions; for every action, there is an equal and opposite reaction; if you push on something, it will push on you

Newton's Third Law


F = G x M1 x M2/ r^2 the force that holds us on the earth holds the earth in its orbit; if you combine this with newton’s second law, you can derive Kepler’s laws of motion for planets

Newton's Universal Law of Gravity


light has wave-like properties (wavelength, frequency); when light is traveling, think of a wave, but when it is absorbed, think about it as particles
- visible light is a section of the electromagnetic wave spectrum
- frequency x wavelength = velocity of light
- wavelength - crest to crest or trough to trough
- frequency - wavelength/second
- Wavelengths (from long to short) - radio, infrared, visible, ultraviolet, x-ray, gamma-ray

Wave Nature of Light


a perfect emitter and absorber of electromagnetic radiation
- it produces/emits light because of its temperature
- a cave is a good absorber of light



apply ideally to a blackbody; the color changes as a blackbody gets hotter; cooler the temperature the longer the wavelength (red is cooler, blue is hotter)
- ex of a question: Star A - the wavelength of peak intensity is shorter than Star B, so Star A is hotter
- ex: Star A is blue, star B is red, star A is hotter (blue is hotter than red)
- shorter wavelength is hotter, shorter wavelength is blue

Wien's Law


light gets brighter as it gets hotter; the hotter it is, the brighter it is; the hotter the object, the shorter the wavelength of peak intensity is

Stefan-Boltzman Law


rainbow; all colors are shown

Continuous Spectrum


certain wavelengths are bright, but in between them there is virtually no light

emission spectrum


rainbow, but has some wavelengths blacked out because there is no light

absorption spectrum


another feature of waves (has to do with the relative motion of the objects); the amount of increase in the pitch as it comes toward you is a measure of how fast its coming toward you
- when light is coming toward you, it is blue shifted, and it’s red shifted as it goes away from you
- you learn the radial velocity of an object because of this

Doppler Effect


hydrogen fusing to helium

main sequence


no fusion is happening (once all hydrogen is helium); the core is collapsing and heating, but the outer layer is expanding and glowing bright

Red Giant


when the helium core starts fusing to carbon

helium flash


helium is fusing to carbon

horizontal branch


no fusion in the core

asymptotic giant branch