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Astro Quiz 1
parallax, celestial sphere, orbits, precession, ppl, circular v
40
Astronomy
Undergraduate 1
09/13/2009

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Term
AU
Definition
d f E to Sun
Term
Ltyr
Definition
d traveled by lt in one yr
Term
parsec
Definition
d at wh an obj of size 1AU would have an angular sz of 1" (one arcsecond)
Term
arcsecond
Definition
3.26 ltyrs
Term
parallax (p)
Definition
triangulation in astronomy
Term
d=
Definition
1/p
Term
cant m. p for stars...
Definition
greater th 100 parsecs (p is too small)
Term
det poles and =tor of cel sphere by...
Definition
extending axis of rot and =torial plane of E
Term
hyp
Definition
suggested expln for a phen
Term
theory
Definition
testable expln for th ebehavior of nat phen
Term
(2)model
Definition
theoretical construct t reps algo. has vars, w a set of ships bw them
Term
law
Definition
rule for how nature will behave under certain conds
Term
Ecliptic
Definition
plane in wh E orbits sun
Term
autumnal, vernal =noxes
Definition
pts at wh ecliptic cross cel equator
Term
sun moves...
Definition
east in sky 1deg/day
Term
(2)E’s axis of rot is tilted...
Definition
at angle of 23.5˚ f perpendicular to plane of E’s orbit. this causes seasons
Term
summer, winter solstice
Definition
Nernmost/Sernmost pts on suns path on cel sphere
Term
(3)precession
Definition
slow change in orientation of E's axis of rot. caused by gravitational pull of sun. causes pole and equinoz pos.s to shift rel to stars
Term
time f sunrise to sunset...
Definition
ch.es thruout yr due to seasonal ch
Term
solar day
Definition
time it takes sun to move f highest pt on sky on one day to highest pt on second day
Term
sidereal day
Definition
time it takes E to complete one rot ab axis (m.ed w respect to stars)
Term
E moves...
Definition
1deg/day in its orbit runt the sun
Term
(4)Galileo Galilei
Definition
first sci to speak directly to ppl. invented astro telescope (saw moons, craters). studied moon exenively.
Term
(2)Johannes Kepler
Definition
studied movement of planets math.ly. Had idea of elliptical orbits.
Term
(2)Law of Planetary Motion #1
Definition
orbits of planets are ellipses w sun at one focus. Eccentricity e=c/a. (c=d f focus to center, a=semi-ajor axis)
Term
(2)Perihelion
Definition
pt at wh E is closest to sun. E moves fastest at this time
Term
Law of Planetary Motion #2
Definition
line f planet to sun sweeps over equal areas in equal time intervals
Term
(2)Law of Planetary Motion #3
Definition
sq.s of orbital periods of planets ab sun are proportional to cubes of orbital semi-major axes. P^2=a^3 (P=orbital pd in yrs).
Term
P^2=
Definition

=k a^3 in any units.

 

=4Π²

GMo

Term
Law of Motion #1
Definition
every body continues in a state of rest or uniform motion in a straight line unless compelled to ch that state by a force acting on it
Term
Law of Motion #2
Definition
F=ma (a=acceleration)
Term
Law of Motion #3
Definition
For every action hay an opp and equal reaction
Term
(3)E is putting...
Definition
as much force on sun as sun is putting on E. But sun is much more massive, so its force is felt much greater. Hence the E revolves runt the sun
Term
Elliptical path of motion of E =
Definition
suns gravitational pull + E's v in straight line
Term
(2)Laws of U.al Gravitation
Definition
two bodies attract eo w force directly p.al to the mass of ea body and inversely p.al to the sq of the d bw them
Term
The moon falls runt E bc...
Definition
the moons spd is fast enuf that its curvature of falling path is slightly flatter th t of E
Term
(2)circular v
Definition
v an obj must have para to stay in circular orbit. Vc=sqrt(Gm/r)
Term
If planets v is less th circular v...
Definition
the planet will crash dn
Term
(2)If planets v is more th circular v...
Definition
planet will stay in elliptical orbit or escape f orbit
Term
F=
Definition
GMm/r^2, or mv^2/r
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