chapter 4 Flashcards

great informant by apparatus to father/refine light (71 cards)

1
Q

electromagnetic radiation (EM)

A

wavelength, photon, infrared (IR), light, ultraviolet (UV), S-ray, gamma ray, atmospheric window

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2
Q

spectrum

A

spectrograph, ROY-G-BIV

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3
Q

telescope

A

optical, radio, intererometer, refracting, reflecting (Cassegrain), primary lens, primary mirror, prime focus, eye piece

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4
Q

power

A

light-gathering, resolving, magnifying, focal length, diffraction fringe, seeing, adaptive optics, sidereal tracking, photometer, change-coupled device (CCD)

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5
Q

geocentric universe model

A

Aristotle/Ptolemy (Greeks) “perfect” 55 spheres turing at different rates
Plato, philosopher, perfect motion (constant speed, perfect circles) uniform circular motion

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6
Q

Aristotle

A

student of Plato, philosopher

believed the heavens are perfect (circle/sphere) as first principle

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7
Q

first principle

A

natural phenomena appear obvious, explained with no further examination needed

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8
Q

Ptolemy

A

follower of Aristotle, mathematician
published 140 CE geometry model planets move in epicycle around a larger called the deferent solves planet big problem of retrograde motion

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9
Q

heliocentric universe model

A

Copernicus hypothesis
Sun-centered scientific revolution
adoption of new paradigm

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10
Q

Tycho Brahe

A

Tycho’s supernova seen in ‘unchanging starry sphere’ still of Aristotle’s view naked eye not see parallax

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11
Q

parallax

A

apparent motion of an object because of the motion of the observer

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12
Q

Johannes Kepler

A

Tycho’s assistant, 1606 figured Mars orbit is elliptical

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13
Q

elliptical

A

closed curve about two foci

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14
Q

Kepler laws

A

planet motion, empirical

  1. planet orbits are ellipses with the Sun at one foci
  2. line from planet to the Sun sweeps over equal areas in equal periods of time
  3. planet’s orbital period squared in proportional to its average distance from Sun cubed
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15
Q

empirical

A

described on observation only, without account for why occur

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16
Q

semi-major axis (a)

A

is half the longest diameter of ellipse

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17
Q

eccentricity (e)

A

is half the distance between the foci divided by the semi-major axis (1=long, 0=circular)

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18
Q

Galileo Galilei

A

used telescope lenses recreated in his workshop
moon not perfect (mountains that he calculated height of by shadows and imperfect ‘planet’)
later observed Venus go through complete set of Moon-like phases (confirmed by Copernican vs. Ptolemaic)

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19
Q

hypothesis

A

claim of guess that can be tested against reality wit observation and experimentation

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20
Q

theory

A

system of rules and principles applicable to many situations

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21
Q

law

A

many tests, refinements and confirmations such that great confidence as fundamental principle

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22
Q

speed

A

rate of movement (position change) is total distance moved divided by total time taken

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23
Q

velocity

A

is the speed and direction of an object (can change with change of speed and/or direction)

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24
Q

acceleration

A

rate of change of velocity with time, or turning (slowing is negative of deceleration)

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25
Isaac Newton
studied math, physics, physical phenomena (light, gravity, etc.) developed math solutions
26
Newton's three Laws of Motion
general laws that govern all bodies under action of external force 1. body continues at rest, or in a uniform motion in straight like, unless acted upon by some force 2. body's change of motion is proportional to the force acting on it, and in the direction of the force 3. body exerting force on a second body receives back an equal and opposite force from body contact
27
universal theory of gravitation
universal mutual gravitation | Moon in orbit
28
mass
matter making up an object
29
weight
force gravity exerts on an object, thus far from Earth have little or no force (~micro-gravity)
30
inverse square relation
strength of effect decreases in proportion as the distance squared increases first noticed on light then gravity
31
centre of mass
objects orbiting each other actually revolve around a mutual point
32
circular velocity
velocity to keep circular orbit | above atmosphere
33
geosynchronous
eastward rotation with Earth
34
closed orbit
returns to starting point (ellipse or circle) making a circular orbit with escape velocity (velocity to escape planet) an open orbit will not return (parabola or hyperbola)
35
Earth's tides
whole ocean bulge seen at coasts, by gravitational force from Moon and Sun (less so) spring tide neap tide
36
spring tide
new and full Moon align with Sun to create larger/extreme range (highest/lowest) tide
37
neap tide
smaller/milder tidal range at first and third quarter Moon
38
electromagnetic (EM) radiation
combination of electric and magnetic waves, spreads from source
39
wavelength
period between waves | light about 0.0005 mm
40
light is a particle
called photon, a quantum (smallest) bundle of electromagnetic waves
41
infrared (IR)
between 700 nm to about 1 mm | beyond range of human eyes, but felt as heat
42
light is a wave phenomenon
the visible portion of the EM spectrum (makes colours of rainbow)
43
ultraviolet (UV)
shorter than violet wavelength
44
x-ray
difficult to focus because they pass through most mirrors
45
gamma ray
higher frequency and shorter wavelength carries more energy
46
atmospheric window
wavelengths at which our atmosphere is transparent to 'em' radiation ozone layer at 30 km absorbs almost all UV, water vapour absorbs IR
47
speed of light
about 300000 km/s in space | true of all electromagnetic radiation
48
electromagnetic spectrum
the same phenomenon as light
49
spectrograph
spread light out according to wavelength into a spectrum for analysis multiple prisms for maximum spread, photographic plate for record
50
nanometer (nm)
one-billionth of a meter (10^-9) visible light wavelength between 400nm and 700nm visual (indigo, violet, blue, green, yellow, orange, red)
51
optical telescope
lenses and/or mirrors are needed to gather light
52
radio telescope
gather intensity of radio radiation (energy) from a spot in the sky
53
interferometer
two or more telescopes combine to make diameter equal to distance between them
54
refracting
lens gathers and bends light to concentrate it to make an image
55
primary lens (objective lens)
is the main collecting lens (at front)
56
reflecting
mirrors gather and bounce light to concentrate it to make an image
57
primary mirror (objective mirror)
is the main collecting mirror (at bottom) | light continues up to focus within the prime focus cage or redirect
58
secondary mirror
redirect light down into hole on primary to instruments is Cassegrain focus smaller telescopes can direct with mirror to eyepiece on the side is Newtonian focus
59
eyepiece
a lens to magnify an image, a short focal length lens
60
telescope power
main function is to make faint things brighter (diameter most important, go larger)
61
light gathering power
diameter (light bucket), proportional to the area of t primary objective
62
resolving power
diameter of telescope objective to reveal fine detail, eliminate diffraction fringe blur fringe caused by wave property of light, 2m objective has fringes 1/2 as large as 1m
63
magnifying power
least important, ability to make image large | focal length of the primary divided by the focal length of eyepiece
64
focal length
distance from a lens or mirror to the formed image
65
seeing
condition of atmospheric turbulence that causes star twinkle, motion makes poor observing mountain location about atmosphere, avoid light pollution
66
light pollution
light from big cities and outdoor waste illumination
67
adaptive optics
are rapid computer controlled calculation and adjustment correcting for poor seeing expensive, difficult compensation for distortion, partial correction
68
sidereal tracking
nonstop movement pointing telescope at stars as Earth rotates (from a clock drive)
69
photometer
measure brightness of individual objects, precise
70
charge-coupled device (CCD)
image recording device and photometer, chip, million+light detectors
71
array detector
size of postage stamp, digitized (numerical data), highly sensitive to bright and faint can manipulate CCD camera data and create false-color images for different levels of intensity