Term
|
Definition
| average Earth-to-Sun distance |
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Term
|
Definition
α = angular diameter D = linear diameter (real diameter of the object you are observing) d= distance (between observer and object) |
|
|
Term
How many arcminutes are in 1 degree? How many arcseconds are in an arcminute? |
|
Definition
60 arcminutes (60') in 1 degree 60 arcseconds (60") in 1 arcminute |
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|
Term
| How do you calculate angular separation? |
|
Definition
| Use the small angle approximation. a will be the angular separation and d will be the distance between the observer and the object as before (assuming the 2 objects are equal distances away) and D will be the angular separation (it is like you are observing an object of that size, the object being the distance between the 2 objects). This looks like a triangle when drawn out. |
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Term
|
Definition
| 88 named constellations represent REGIONS OF THE SKY |
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Term
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Definition
| From our perspective, the sky appears to be a 2-d surface of a spherical dome. The celestial sphere is an earth centered model for locating objects in the sky. |
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Term
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Definition
| point directly overhead (look straight up) on the celestial sphere (relative to observer) |
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Term
|
Definition
| circle oriented N-S passing through the zenith |
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|
Term
| North Celestial Pole (NCP) |
|
Definition
point on the celestial sphere directly above the north
if your zenith is NCP, it is 90 degrees above the horizon |
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Term
|
Definition
| "North Star" located approximately at NCP |
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Term
|
Definition
a star that neither rises or sets, but rotates around one of the celestial poles
ex: if your zenith is NCP, Polaris remains stationary while stars appear to rotate around it |
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Term
|
Definition
a portion of a recognized constellation Ursa Major
the "pointer stars" in the Big Dipper point towards Polaris |
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Term
|
Definition
|
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Term
|
Definition
"terrestrial planets"
Mercury, Venus, Earth, Mars |
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Term
|
Definition
"Jovian planets"
Gas giants |
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Term
|
Definition
| elevation (angle) above the horizon |
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Term
|
Definition
compass direction towards the object
north = 0 degrees
east = 90 degrees
south = 180 degrees
west = 270 degrees
"never eat soggy wieners" |
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Term
|
Definition
the apparent annual path of the sun across the sky
position of the moon and planets in the sky is always close to the ecliptic because all the planets are BASICALLY on the same plane |
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Term
|
Definition
| the plane of Earth's orbit |
|
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Term
| what creates the seasons? |
|
Definition
Earth's axial tilt of 23.5 degrees
the Earth is colder in winter because the amount of sunlight per square meter is less
if Earth's axis were perpendicular to it's orbital plane, the sun would always appear on the Celestial Equator |
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Term
| In which direction does the Earth rotate? |
|
Definition
from a location in space above the North Pole (conventional view), COUNTERCLOCKWISE
ALL planets' ORBITS are COUNTERCLOCKWISE
MOST planets' ROTATIONS are COUNTERCLOCKWISE |
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Term
|
Definition
| time between successive "solar noons" (=24 hours) |
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Term
|
Definition
| time required for one APPARENT revolution of the stars AND the time for Earth to rotate 360 degrees (=23h 56min) |
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|
Term
| A star rises __ minutes earlier each day. Why? |
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Definition
| 4, because a siderial day is only 23h 56min |
|
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Term
| Precession of Earth's axis |
|
Definition
| the Earth is "spinning like a top"- it's axis is slowly drawing a circle. the period of precession is 25,000 years, and causes the "North Star" to change over time |
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Term
|
Definition
| all stars are in motion with high relative velocities, so stars shift over time |
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|
Term
Phases of the moon picture (be able to reproduce and flip) |
|
Definition
|
|
Term
|
Definition
time for moon to orbit 360 degrees
(27.3 degrees) |
|
|
Term
|
Definition
time for one cycle of phases of the moon
(29.5 days) |
|
|
Term
| Synchronous rotation of the moon |
|
Definition
the moon's rotational period is synchronous with the siderial period (time it takes moon to orbit 360 degrees) of it's orbit
Result: moon shows (approx) the same face towards Earth at all times
Note: this is not a coincidence and there is a physical reason |
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Term
|
Definition
the Moon casts a shadow on Earth
occurs only at New Moon (but not at every New Moon) |
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Term
|
Definition
Earth casts a shadow on the Moon
occurs only at Full Moon (but not at every Full Moon) |
|
|
Term
|
Definition
| darkest shadow; light completely blocked |
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Term
|
Definition
| only part of light source is blocked |
|
|
Term
| Why don't eclipses occur every month? |
|
Definition
| Moon's orbit is tilted 5 degrees relative to the ecliptic plane (plane of Earth's orbit around the sun) |
|
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Term
|
Definition
| eclipses can occur only when Full Moon or New Moon coincides with passage of the Moon through the ecliptic plane (along a "line of nodes") |
|
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Term
|
Definition
| line of intersection of ecliptic plane and Moon's orbital plane |
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Term
|
Definition
| sun's outer atmosphere which is visible during a total solar eclipse |
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Term
|
Definition
| seen from inside penumbra (when moon casts shadow on earth) |
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Term
|
Definition
| sun's corona is visible; seen from umbra (when moon casts a shadow on earth) |
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Term
|
Definition
| moon near apogee (smallest angular diameter) so the lunar disc is too small to cover the solar disc, causing a thin ring of sun to remain visible (when moon casts a shadow on earth) |
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Term
|
Definition
| the path along the earth on which total solar eclipse is observed |
|
|
Term
| how often do lunar eclipses occur? |
|
Definition
1-2 per year
total and partial eclipses are visible from all over the Earth's night side, but penumbral eclipses are not readily apparent |
|
|
Term
| how often do solar eclipses occur? |
|
Definition
1-2 per year
visible from a portion of earth's sunlit side |
|
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Term
|
Definition
earth-centered view widely held in ancient Greece and mid-east
ex: Aristotle, Ptolemy; influenced by Plato who said "reason is superior to observation" |
|
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Term
|
Definition
| the apparent "backward" movement of planets relative to stars |
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Term
|
Definition
|
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Term
|
Definition
earth and moon are spherical, sun farther away from earth than moon
however, also believed earth is stationary center of the universe |
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Term
|
Definition
moon is smaller than earth, sun larger, all planets orbit the sun, earth rotates on axis
however, ideas not widely accepted |
|
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Term
|
Definition
early 1500s
"founder of modern astronomy"
rediscovered the heliocentric model (already discovered by Aristarchus in Egypt) |
|
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Term
|
Definition
late 1500s
first modern observatory
compiled meticulous observations of planet positions |
|
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Term
|
Definition
early 1600s
first telescopic study of celestial objects
observed:
Jupiter's four largest moons
phases of Venus
sunspots (sun rotates on axis)
features on surface of moon
concluded: sun center of solar system |
|
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Term
|
Definition
early 1600s
Tycho Brahe's successor
Kepler's laws: elegant mathematical descriptions of planetary orbits |
|
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Term
|
Definition
| Newton's laws of motion and gravity were fundamental laws from which Kepler's laws could be derived |
|
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Term
|
Definition
1) the orbits of planets are ellipses with the sun at one focus
2) a line joining a planet to the sun sweeps out equal areas of space in equal intervals of time
3) the square of the orbital period of a planet is proportional to the cube of it's average orbital radius
P^2~a^3 |
|
|
Term
|
Definition
longest axis of an ellipse
AVERAGE ORBITAL RADIUS |
|
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Term
|
Definition
defines the shape of an ellipse between 0 and 1
e=0 is a perfect circle
e=1 is a parabola
e>1 is a hyperbola
for most planets, e<0.1 |
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|
Term
| an ellipse has... (geometrically) |
|
Definition
2 focuses (foci) which are the halfway points between the ends of the semimajor axises from the center
AND
r1+r2=2a(length of the major axis (both semimajor axises))=constant
r2= distance up from f2 to the top of the ellipse
r1= distance between f1 and where r2 touches the edge of the ellipse
if r1+r2 is constant, that means that as the triangle is changing, the distance remains constant |
|
|
Term
|
Definition
point of closest approach to sun
distance=a(1-e)
for moon, perigee
for any orbit, periapsis |
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Term
|
Definition
maximum distance from the sun, aphelion=a=away
distance=a(1+e)
for moon, apogee
for any orbit, apoapsis |
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Term
|
Definition
P^2~a^3
for planets and smaller bodies ORBITING THE SUN, P^2=a^3, P in siderial (apparent ie not 365 days) years, a in AU
for ANY two bodies orbiting eachother, P^2=4pi^2a^3/G(m1+m2)
m in kg
P in s
a in m
G = gravitational constant |
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|
Term
|
Definition
1) a body remains at rest or in motion in a straight line, unless acted on by a net external force
2) F = ma
3) to every action there is an equal and opposite reaction |
|
|
Term
| Newton's universal law of gravity |
|
Definition
F=Gm1m2/r^2
G= constant
r= center to center distance b/w 2 objects |
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|
Term
| Objects in earth orbit are freely falling toward Earth, but... |
|
Definition
| their high speed prevents them from reaching the surface. If velocity is high enough, a projectile enters an elliptical orbit with the center of Earth at one focus |
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Term
| Circular orbits (velocity) |
|
Definition
speed required to maintain a circular orbit of radius r about a body with mass M Vorb=√(GM/r) so r is measured from the center of mass M and is the RADIUS OF THE ORBIT, NOT AN OBJECT another way to find orbital speed for circular orbits: V=d/t =circumference of orbit/ period of orbit =2∏r/P |
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Term
|
Definition
Ve=√(2GM/R) for escape from the surface: M=mass of planet (or asteroid or moon etc) R=radius of planet for escape from a circular orbit around a planet R=radius of orbit (measured from center of planet) |
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|
Term
| How can we change the orbit of man-made satellites? |
|
Definition
Hohmann semi-elliptical transfer orbit
fire motors at apogee to enter higher and higher orbits (higher PEgrav)
fire "retro thrusters" to slow down spacecraft to move into lower and lower orbits (lower PEgrav)
(PEgrav = gravitational potential energy) |
|
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Term
|
Definition
how we send space craft to other planets
when far from planets, space craft is "fallin" in orbit around the sun. if it approaches a planet, planet's gravity can be used to "boost" the spacecraft into a different orbit (w/o burning fuel). space probes to outer planets always use gravitational assists. |
|
|
Term
| Tidal force (differential gravitational force) |
|
Definition
for two bodies m1 and m2 separated by distance r, tidal force exerted on m2 by m1 is
Ft=Gm1m2R2/r^3 where R2=radius of m2 and r = distance b/w m1 and m2 |
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|
Term
| effects of tidal force exerted BY moon ON earth |
|
Definition
1) ocean tides- "stretching effect on planet earth causes ocean water to bulge out on BOTH SIDES of earth. ocean bulge is small in deep water ~1m. in coastal regions, high and low tides occur twice a day as earth rotates under the ocean bulges. sun also exerts tidal force on earth. maximum ("spring") tides occur when the sun and moon are aligned (new moon/full moon)
2) "body tides"- stretching effects on SOLID earth. surface of earth bulges out 10-20cm on each side. earth is relatively RIGID and ROTATING, causing solid tidal bulges that are not aligned to the direction of the moon because it takes several hours for the earth to stretch, and by the time it is done being stretched, it is out ahead of the moon and the moon pulls on it, causing...
3) earth's rotation rate is decreasing because the moon's gravity tugs backward on earth's near bulge as the earth rotates, so the earth COULD eventually rotate syncronously with the moon |
|
|
Term
| tidal forces exerted BY earth ON moon |
|
Definition
1) moon's synchronous rotation- earth's "tugging" has slowed moon's rotation so its tidal bulges are always aligned toward earth
2) moon's orbital radius is increasing because earth's near bulge tugs the moon forward in it's orbit so the moon speeds up and moves farther away |
|
|
Term
|
Definition
| a form of electromagnetic radiation- energy that travels in the worm of oscillating electric and magnetic fields |
|
|
Term
| characteristics of electromagnetic radiation (EM) |
|
Definition
no mass, no charge
velocity is constant in a vacuum
wave particle duality: light exhibits both wave like properties and particle like properties |
|
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Term
|
Definition
| distance between successive maxima |
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Term
|
Definition
| number of full wave cycles passing by every second |
|
|
Term
| particle-like properties of light |
|
Definition
EM radiation is quantized- it travels as discrete bundles of energy called photons. with sensitive detectors, one can measure photons and count them.
Ephoton = hf = hc/lambda
h=Planck's constant |
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Term
|
Definition
all "warm" objects (T>0K) emit EM tells us the surface temperature of a star |
|
|
Term
Planck curve
aka Blackbody spectrum, Continuous thermal emission spectrum |
|
Definition
plot of radiation intensity vs. wavelength for an object at some temperature T
hotter objects are brighter and "bluer" than cooler objects |
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Term
|
Definition
labmda max=.0029/T
lambda = peak wavelength in m
T=temp (K) = T Celsius +273 |
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Term
|
Definition
F=σT4 F=energy radiated per second per square meter of emitting surface (watts/m2) |
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Term
|
Definition
luminosity = total emitted power L = F x surface area units: watts (joule/sec) for star/planet radius R: L=4∏R2σT4 |
|
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Term
|
Definition
| give us chemical info about stars, gas clouds, etc. |
|
|
Term
| Kirchoff's laws of spectroscopy |
|
Definition
1) a hot material (solid, liquid, dense gas) radiates a continuous spectrum whose characteristics are described by the blackbody curve (Planck's curve)
2) a hot gas produces a discontinuous spectrum of bright emission lines
3) if the continuous spectrum from a hot source passes through a gas, specific wavelengths are absorbed, producing an absorption spectrum |
|
|
Term
| all stars contain the same elements, but... |
|
Definition
| many stars have different chemical abundances different from sun |
|
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Term
|
Definition
1) electrons orbit the positive nucleus
2) electrons may exist only in specific energy levels or "orbitals," but may jump to a higher energy level by absorption of photons with just the right energy. such electrons are in an "excited state" which is less stable, which is followed by emission of a photon as the electron drops back to lower energy level
energy of absorbed photon = difference between energy levels |
|
|
Term
| a gas absorbs and emits _______ wavelengths |
|
Definition
|
|
Term
| emission/absorption spectrum uniquely identifies... |
|
Definition
|
|
Term
|
Definition
perceived wavelength and f depend on the component of motion of source relative to observer along a line-of-sight b/w them
=radial velocity |
|
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Term
|
Definition
star coming toward earth: blue-shifted star receding away from earth: red-shifted Doppler equation: Δλ/λ0=v/c Δλ=(λ-λ0) λ0= intrinsic value (emitted from source) λ= observed value v=velocity of source relative to observer v>0 = recession v<0 = approach |
|
|
Term
|
Definition
collect and focus (mainly) visible light
2 types: refractors use lenses, reflectors use mirrors |
|
|
Term
| "cassegrain focus" reflector |
|
Definition
| light passes through a hole in the primary |
|
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Term
|
Definition
| a system of mirrors used to divert the image into ex: spectrometer |
|
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Term
|
Definition
determines how far you can see (how faint)
is proportional to light collecting area ~ D^2
D= aperture (diameter of lens or mirror) |
|
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Term
|
Definition
determines the level of detail
How far apart must 2 objects be in order for you to "resolve" them as 2 distinct objects?
O=resolving power of a telescope=smallest angular separation that can be distinguished
O~lambda/D |
|
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Term
|
Definition
how clear is the sky?
interference of earth's atmosphere |
|
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Term
|
Definition
| diameter of lens or mirror |
|
|
Term
| theoretical angular resolution |
|
Definition
for any wavelength:
O(arc seconds)=(2.5x10^5)lambda/D
for visible light:
O(arc seconds)=(.14)/D |
|
|
Term
| if the angular size of an object is larger than the angular resolution of your telescope, then... |
|
Definition
| you can see (resolve) that object |
|
|
Term
|
Definition
| blue light is refracted more strongly than red because different wavelengths have different focal points. this is unavoidable in refractors even if the lens is perfect. |
|
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Term
|
Definition
1) chromatic aberration
2) lens warping- lens mount supports lens by its thin edges; glass is not completely rigid
SOLUTION TO ALL PROBLEMS: reflecting telescope, b/c only one optical surface and mirrors can be supported from the back to minimize warping |
|
|
Term
|
Definition
| scattered light (bright sky background); atmospheric turbulence smears out image and reduces resolution; moisture and other gases absorb certain wavelengths |
|
|
Term
| atmospheric "windows" for EM radiation |
|
Definition
atmosphere is relatively permeable to visible wavelengths; absorbs many infrared wavelengths; completely absorbs gamma, X, and most of the UV spectrum
this creates a need for space based telescopes |
|
|
Term
| solutions to problems for large telescopes |
|
Definition
active optics: computer controlled actuators support the mirror and curvature is constantly monitored and adjusted in real time to control mirror warping.
adaptive optics: limit atmospheric distortion |
|
|
Term
| problems with infrared telescopes |
|
Definition
atmospheric absorptions: need high altitude and dry air
object at room T radiate IR so refrigeration is required |
|
|
Term
|
Definition
| radio waves have long wavelengths and low energy, so large collectors are needed but shape need not be as perfect as optical reflector |
|
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Term
|
Definition
| radio telescopes: twenty seven 25m dishes |
|
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Term
|
Definition
My very easy method: just stop using nine
Mercury
Venus
Earth
Mars
: (asteroid belt including Ceres)
Jupiter
Saturn
Uranus
Neptune
(Pluto)
(Eris) |
|
|
Term
| characteristics of terrestrial planets |
|
Definition
1) inner planets, close to sun
2) small size, high density
3) solid rocky surface (mostly silicate rocks), impact craters, signs of volcanic activity (past or present)
4) "thin" or no atmosphere (CO2, nitrogen, O2)
5) few or no moons
6) slower rotation period |
|
|
Term
| characteristics of outer "jovian" planets |
|
Definition
1) outer planets: cold, far from sun
2) huge size, low density
3) thick, deep atmosphere (H, He)
4) no solid surface: apparent surface = cloud tops (probably tiny rocky core deep inside)
5) many satellites, ring systems are common
6) rapid rotation rate (10-17h) |
|
|
Term
| the nature of a planet's atmosphere is determined by what 3 characteristics? |
|
Definition
temperature: gas molecules move at high speed- if speed>Vesc, gas escapes. terrestrial planets are too small/hot to retain much H2 and He in atmosphere
gravity: small planets have lower gravity
history |
|
|
Term
| A significant ________ ________ is one indication of a dynamic interior |
|
Definition
|
|
Term
| What determines if a planetary interior is dynamic or not? |
|
Definition
| balance between internal heat production and rate of heat loss to space |
|
|
Term
| what led to the formation of the sun and planets? |
|
Definition
| the collapse of the solar nebula |
|
|
Term
|
Definition
| spinning cloud of interstellar gas and dust composed of 98-99% H and He |
|
|
Term
| stages of solar system formation |
|
Definition
1) collapse of solar nebula
2) nebula spins faster due to conservation of angular momentum and flattens into a disc. most of the mass falls into the center of the nebula, creating the sun and the centrifugal force (cons. of angular momentum) prevents the remaining material from falling into it.
3) outer portion cools -> gases condense, grains clump together
4) gravitational accretion of larger clumps to form planitesimals
5)collisions between large planetesimals result in fragmentation: only the largest protoplanets survive
6) "sweeping up" of remaining debris by large planets resulting in one large body in each region of the solar system |
|
|
Term
| all objects in the solar system are believed to have formed from ______ ______ at approx the ______ ______. |
|
Definition
| similar materials, same time |
|
|
Term
|
Definition
atmosphere and ocean: the life zone, a very thin skin
crust: few to 70km thick
2 types- continental crust (low density, granite) and oceanic crust (medium density, basalt)
mantle: 2900km thick
solid rock, denser than crust
P and T increase with depth
high T- mantle behaves like a very viscous fluid
mantle convects (very slowly)
evidence: folded crustal layers are evidence of plastic deformation in solid rock when subjected stress at high P, T
core: iron-nickel metal, very high density; outer core liquid, inner core solid |
|
|
Term
|
Definition
| hot material flows upward, cools downward; transports heat from interior to surface; drives plate tectonics at surface |
|
|
Term
|
Definition
| crust is divided into approx 12 major rigid plates that are in motion. earthquakes, volcanoes, mountain building are evidence of earth's dynamic interior |
|
|
Term
|
Definition
process by which initially homogeneous material is separated into chemically distinct portions
Differentiation in planetary bodies is the formation of a dense core surrounded by lighter material
Earth is a differentiated body- early Earth was probably mostly molten. silicate and metal liquids are immiscible. iron-rich liquid sank toward center. |
|
|
Term
| what causes earth's magnetic field? |
|
Definition
| rapid convection of conducting liquid plus earth's rotation creates a "dynamo," resulting in earth's magnetic field |
|
|
Term
|
Definition
| magnetic field with N and S pole |
|
|
Term
| characteristics of earth's magnetic field |
|
Definition
magnetic axis is tilted 15 degrees relative to rotation axis
pole migrates
strength is decreasing
periodically switches polarity (N becomes S) |
|
|
Term
|
Definition
| region of influence of Earth's magnetic field which is distorted by solar wind |
|
|
Term
|
Definition
| high energy charged particles ejected from sun |
|
|
Term
|
Definition
| magnetic field traps solar wind particles which protects the surface of earth |
|
|
Term
|
Definition
high energy particles spiral about magnetic field lines, and near the poles they collide with (and ionize or excite) atmospheric molecules which may be followed by the emission of visible light
Aurora Borealis (northern lights)
Aurora Australis (southern lights) |
|
|
Term
| characteristics of earth's atmosphere |
|
Definition
| 100km thick but 90% of mass is below 11km of altitude. |
|
|
Term
| structure (layers) of earth's atmosphere |
|
Definition
troposphere- 90% mass
stratosphere- 10% of mass
mesosphere, thermosphere (aka ionosphere) - <1% of mass |
|
|
Term
|
Definition
second layer of atmosphere, contains 10% of mass
includes ozone layer |
|
|
Term
|
Definition
first layer of atmosphere, 90% of mass
zone of convection and weather |
|
|
Term
|
Definition
| absorbs x-rays and gamma rays |
|
|
Term
|
Definition
|
|
Term
|
Definition
| gases absorb IR radiation, warming the surface, allowing liquid oceans and moderate surface temperature |
|
|
Term
| "solar nebula" theory solar system |
|
Definition
| earth and moon (and all other planets) formed from similar materials at approx the same time |
|
|
Term
|
Definition
means "sea"
huge craters filled with basalt; dark, med density rock; gentle rolling terrain with relatively few craters |
|
|
Term
|
Definition
| rough, mountainous terrain; craters everywhere, all sizes; light colored, less dense rock |
|
|
Term
|
Definition
| lunar "soil": rock pulverized by occasional large impacts and constant micrometorite bombardment |
|
|
Term
| youthful craters of the moon have _____ |
|
Definition
| rays, bright radial features |
|
|
Term
|
Definition
| probably formed by lava channels; evidence of past volcanic activity |
|
|
Term
|
Definition
| huge impact basins that were filled with lava |
|
|
Term
|
Definition
| small (or no) iron core; completely solid OR might have a "mushy zone"; no evidence of vigorous convection |
|
|
Term
| currently accepted theory of moon origin |
|
Definition
moon formed in the aftermath of a catastrophic collision between a Mars-sized planet and proto-Earth
evidence:
oxygen isotopes, volatile element depletion on moon, Earth has larger core, evidence of late catastrophic collisions elsewhere in solar system ex: Uranus |
|
|
Term
| Mercury's density is similar to Earth but Earth is larger and more "compressed." Conclusion: Mercury is made of materials that are ________ _______ than Earth and has a relatively ______ ______. |
|
Definition
| intrinsically denser, large core |
|
|
Term
| A larger planet will have _______ density due to ______ _______. |
|
Definition
| greater, gravitational compression |
|
|
Term
| Mercury has a ____ rotation and ____ atmosphere. |
|
Definition
| slow, no (thin "transient" atmosphere) |
|
|
Term
| Mercury has _____ temperature variation |
|
Definition
extreme
daytime high 450 degrees C
nighttime low -160 degrees C |
|
|
Term
| Mercury's spin orbit coupling |
|
Definition
3x rotation period = 2x sidereal period
=3:2 spin orbit coupling
Result: sun rises in east, sets in west; near perihelion, sun moves eastward for a few (earth) days |
|
|
Term
|
Definition
| shockwaves from impact converged on "backside" causing violent surface deformation |
|
|
Term
|
Definition
Molecules dislodged by solar wind OR diffusing out
from subsurface rock due to solar heating |
|
|
Term
| Why is Mercury's magnetic field so weak (.01x Earth's)? |
|
Definition
Rotation too slow to drive electromagnetic “dynamo”
OR Core may be mostly solid |
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Term
Mercury’s magnetic field is stronger
than a remnant magnetic field, meaning... |
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Definition
| Mercury may have have an active dynamo |
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Term
Why is Earth not heavily
cratered? |
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Definition
1. Surface erosion (wind, water, freeze/thaw)
2. Plate tectonics “recycles” crustal plates
Old crust destroyed by subduction
New crust created at spreading ridges |
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Term
| Mechanics of Crater Formation - Stages |
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Definition
1. Contact/compression
2. Excavation
3. Infall/modification |
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Term
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Definition
| uplift in the middle of a complex crater |
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Term
| Venus' retrograde rotation is evidence of... |
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Definition
| a major collision during late stages of formation |
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Term
| Venus' surface characteristics |
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Definition
dominated by volcanic plains (basalt)
impact craters- large, but relatively few
highlands: Ishtar Terra:
crustal compression mts (like Himilayas?), Maxwell Montes (shield volcano, basalt?), volcanic collapse calderas, a few impact craters |
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Term
| Venus is a near twin of Earth in _____ and _____. |
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Definition
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Term
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Definition
| mostly CO2; surface P is 90x Earth's atmospheric pressure; 100% cloud cover (sulfuric acid) |
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Term
| Venus' surface temperature |
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Definition
| 750K with little variation (Greenhouse effect) |
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Term
| Venus' surface can be mapped using... |
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Definition
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Term
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Definition
10% highlans
90% rolling plains
no deep basins |
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Term
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Definition
45% highlands
55% deep ocean basins |
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Term
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Definition
| "pancake" domes: 750m high eruptions of thick, viscous laba |
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Term
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Definition
| volcanic collapse feature |
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Term
| Does Venus have tectonic activity? |
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Definition
| Yes (crustal stresses, faulting, mountains), but no evidence for global plate tectonics |
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Term
| Mantle convection is (more/less) organized on Venus |
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Definition
| less, there are signs of upwelling and downwelling, little horizontal flow in mantle, and no large-scale convection cells (as seen on Earth) |
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Term
| Earth's major internal heat sources |
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Definition
1. Radioactive Decay
2. Release of latent heat inside core |
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Term
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Definition
| due to localized, rising hot rock/magma (mantle plumes); relatively minor on earth, but Venus heat transfer may be dominated by this |
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Term
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Definition
| may be surface expression of rising mantle plumes |
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Term
| atmospheric evolution of Earth and Venus |
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Definition
1. primary atmosphere- H, He (lost to space)
2. secondary atmosphere- CO2, H2O,(few % N2) outgassed from molten interior
then both planets cool/solidify...
earth: surface T drops below 100 degrees C, water condenses and forms oceans
venus: surface T > 100 degrees C, no oceans, dissociation of water vapor causing H to be lost to space
venus has continued volcanism, causing CO2 buildup in atmosphere, "Runaway" greenhouse effect, and surface T to rise near 480 degrees C
earth, however, had the origin of life and biogeochemical cycles
1. photosynthesis: organisms take in CO2 and give off O2
2. CO2 is gradually removed from atmosphere and stored in limestone deposits
3. build up of O2 rich atmosphere |
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Term
| two models for tectonic differences b/w Earth and Venus |
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Definition
model 1:
earth: wet oceanic plates are subducted into mantle, where water reduces mantle viscosity (increases fluidity) and encourages convection -> mantle convection efficiently transports heat from interior to surface
venus: no ocean, little water in mantle; rigid mantle causes large convection cells to be inhibited -> heat transport less efficient causing "hot spots," regions of upwelling that bulge out asymmetrically and exhibit unusual crustal stress patterns
model 2:
venus: heat transport more efficient; mantle convection on Venus is vigorous; crust is hot, thin, pliable -> no Earth-style plate tectonics -> "flake tectonics" |
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Term
| Mars' large scale surface structures |
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Definition
| huge basaltic "shield" volcanoes; Valles Marineris, the largest valley in the solar system; North-South asymmetry |
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Term
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Definition
southern hemisphere: highlands, heavily cratered
northern hemisphere: lowlands, few craters, more evidence of surface professes (flow features, erosion)
conclusion: north hemi's surface is younger |
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Term
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Definition
| Olympus Mons, the largest volcano in the solar system |
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Term
| Surface processes on Mars |
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Definition
early: global volcanism, heavy cratering
later: continued volcanism (mainly in North), erosion by surface water, ice, and wind
now: no volcanic activity or surface water |
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Term
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Definition
| crack due to crustal stresses on the surface of Mars; has been modified by erosion |
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Term
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Definition
| ancient river channels; evidence for past glacial ice sheets; probably subsurface ice today, and possibly liquid water under the polar caps |
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Term
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Definition
small core or S-rich core
no magnetic field
no plate tectonics
no current volcanism |
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Term
| Why does Mars have such huge volcanoes? |
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Definition
1. No plate tectonics, allowing hotspot to grow a single, immense volcano rather than a chain of volcanoes
2. thick, cool "lithosphere" (crust+rigid part of mantle) combined with lower gravity, allowing support of larger edifices |
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Term
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Definition
| crust + rigid part of mantle |
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Term
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Definition
like Venus, mostly CO2
pressure <1% of Earth surface P
weather: high winds, dust storms |
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Term
| current surface processes on Mars |
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Definition
| wind erosion; impact cratering; landslides (gravitational slumping); subsurface water (ice) occasionally mobilized |
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Term
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Definition
could be water ice or frozen CO2
seasonal variation on Mars' North polar ice cap
permanent cap: water ice
seasonal cap: dry ice (frozen CO2) |
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Term
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Definition
| tiny, probably captured asteroids (Phobos and Deimos) |
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Term
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Definition
| one of Mars' moons: orbital period is longer than Mars' rotation period; Mars' tidal bulge tugs Deimos forward, causing it to gain KE and recede from Mars |
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Term
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Definition
| one of Mars' moons: orbital period is less than Mars'; Mars' tidal bulge tugs Phobos backward, decreasing KE and causing it to spiral inward toward Mars |
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Term
| Traits shared by gas giants |
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Definition
| large size, low density; rapid rotation rate (10-17hr); oblate spheroidal shape (flattened at poles due to rapid rotation rate and low rigidity); abundant orbiting debris (moons, rings) |
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Term
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Definition
| low density; gaseous (H, He) with a small rocky core; huge gravitational field affects all other bodies esp. asteriods/comets; centre of it's own mini solar system with many moons and a faint ring system; large magnetic field; major internal energy source |
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Term
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Definition
| very low density; at least 47 moons and a major ring system; magnetic field |
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Term
| Rotation rate of gas giant =... |
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Definition
| rotation rate of magnetic field |
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Term
| Magnetic fields arise due to... |
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Definition
| convection/rotation of electric currents in metallic H layer |
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Term
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Definition
Molecular H layer: gaseous above; liquid below
Metallic H layer: liquid, source of magnetic field |
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Term
| possible internal energy sources for gas giants |
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Definition
1. continued contraction/differentiation ex: "He rain" in Saturn- precip releases latent heat
2. dissociation of methane may occur at high P,T |
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Term
| _____ gas giants have rings |
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Definition
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Term
| saturn's rings are composed of... |
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Definition
| chunks of ice (mostly gravel to boulder sized) with some rocky particles |
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Term
| other gas giants' (besides saturn) rings are composed of... |
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Definition
| fine, dust sized particles |
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Term
| why don't particles around Saturn accrete to form a moon? |
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Definition
| tidal forces are too strong; these rings are within Saturn's Roche Limit |
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Term
| for small bodies orbiting outer planets, the Roche limit for a zero-strength object is... |
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Definition
R0=2.5R
R0 = distance from center of planet
R = radius of planet
within this distance, small objects cannot accrete to form a moon |
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Term
| for small bodies orbiting outer planets, the Roche limit for an icy moon (>30km diameter) |
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Definition
R0=1.4R
within this distance, an icy moon would be fragmented by tidal forces
b/w 1.4-2.5, an icy moon could exist, but not form |
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Term
| probably fates of small debris in the solar system |
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Definition
| collide with another body, fall into the sun, or escape from the solar system |
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Term
| likely source of planetary ring systems is... |
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Definition
| collisions of small moons |
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Term
| characteristics of satellites of the outer solar system |
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Definition
large: round, differentiated
small: irregular shape, undifferentiated
composition: rock and ice
heat source: tidal interaction with planet and other moons; stronger heat source means younger surface and lower ice/rock ratio |
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Term
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Definition
moon of Jupiter (Galilean); extremely active, young surface
the most volcanically active body in the solar system!!
S-rich volcanic deposits |
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Term
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Definition
4 largest moons of Jupiter
closest: very active, Io
Europa
Ganymede
farthest: old cratered surface, not active, Callisto |
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Term
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Definition
Galilean moon
smooth surface (no mountains, few craters)
icebergs floating on a water ocean- evidence for icy crust over liquid water: frozen puddles, icebergs, cracks/ridges associated with fresh ice "eruptions" |
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Term
| ___ and _____ are in orbital resonance with Ganymede. What is the result? |
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Definition
Io, Europa
tidal interaction with Jupiter and neighboring moon enhances internal heating |
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Term
| The probability of life on _____ may be greater than any other extraterrestrial body in the solar system. Why? |
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Definition
Europa
internal heat sources warm the underlying liquid water ocean; diverse organic compounds have been found in comets and probably exist on Europa; on earth, extremophiles have been found at 4km depth in Antarctic ice |
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Term
| Callisto shows evidence of what kind of collision? |
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Definition
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Term
| where did the Galilean satellites come from? |
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Definition
| probably formed along with Jupiter as a "mini-solar system" from an eddy in the solar nebula |
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Term
| where did Jupiter's smaller satellites come from? |
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Definition
| probably captured asteroids |
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Term
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Definition
| battered, chaotic surface: suggest past break up and reassembly |
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Term
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Definition
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Term
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Definition
| retrograde (clockwise) orbit, thin hazy atmosphere, geyser-like "ice volcanoes" |
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Term
| Uranus and Neptune are _____ in size |
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Definition
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Term
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Definition
| active, dynamic atmosphere, Methane clouds, persistent storms |
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Term
| Neptune has a (large/insignificant) internal energy source. |
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Definition
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Term
| Uranus has a (large/insignificant) internal energy source. |
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Definition
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Term
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Definition
| relatively cold, quiescent atmosphere, occasional storms |
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Term
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Definition
| on it's side, retrograde rotation |
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Term
| If there is no metallic H on Uranus and Neptune, what "conducting layer" produces the magnetic dynamo? |
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Definition
| an electrolyte solution: Ammonia ions dissolved in water |
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Term
| Why are magnetic fields not aligned with rotation axis? |
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Definition
| conducting layer may be very thin (relative to planetary radius) |
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Term
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Definition
a region roughly in the ecliptic plane where 1000s of small ice/rock bodies orbit (20-150AU?)
postulated source of short-period comets |
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Term
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Definition
a spheroidal region where trillions of small icy bodies orbit (2000AU-??)
postulated source of long-period comets |
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Term
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Definition
| any object orbiting the sun beyond the orbit of Neptune (includes Kuiper Belt Objects and Oort cloud objects) |
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Term
| Pluto is one of many ice/rock bodies in the _____ _____. |
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Definition
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Term
| Five large, round objects including the largest asteroid Ceres have been classified as _____ ______. |
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Definition
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Term
| Trans-Neptunian dwarf planets similar to Pluto are called ______. |
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Definition
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Term
Comets: "Dirty Snowballs"
composition of comets |
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Definition
| The "nucleus" (solid part) of a comet is composed of frozen gases (ice) and dust. Comets have been in "cold storage" in the outer part of the solar system since the early stages of solar system formation. Gravitational perturbations occasionally cause one to fall towards the sun. |
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Term
| As a comet approaches the sun... |
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Definition
| gases vaporize, ionize and emit light; dust and ionized gases stream off the surface forming the coma; solar wind pressure blows material away from the sun forming the tails |
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Term
| Comets don't last forever. At 5 AU from the sun, comets... |
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Definition
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Term
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Definition
| Internal pressure increases with size (and gravity). If stress exceeds strength of rock (or ice), deformation to spheriodal shape. |
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Term
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Definition
1. in orbit around a star
2. is neither a star nor a satellite of a planet
3. has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (ie is round)
4. has "cleared its orbit" of debris |
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Term
| What do meteorites tell us? |
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Definition
| the age of the solar system, the approx. chemical composition of solar nebula, the nature of planetary cores, evidence of early solar system processes |
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Term
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Definition
natural interplanetary debris that could potentially collide with Earth
large: bolide
small: micrometeoroid |
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Term
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Definition
| brief streak of light observed in sky when a meteoroid is heated during entry to Earth's atmosphere |
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Term
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Definition
| former "meteoroid" that has survived passage through the atmosphere and landed on planet's surface |
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Term
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Definition
| comets, dust from asteroidal collisions, possibly some interstellar grains |
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Term
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Definition
from cores of differentiated asteroids
thin exterior fusion crust |
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Term
| stony meteorites (chondrites, achondrites) |
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Definition
| composed mostly of silicate material |
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Term
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Definition
| tiny droplets of solidified magma in a rock |
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Term
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Definition
("containing chondrules")
an assemblage of diverse small particles that may be preserved primordial material from the solar nebula |
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Term
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Definition
("without chondrules")
igneous rocks from the "mantles" of differentiated asteroids |
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Term
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Definition
| mixture of stony meteorite and iron meteorite |
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Term
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Definition
| achondrites, "young" ages, contain gases that match Mars' atmospheric compostion |
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Term
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Definition
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Term
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Definition
>330,000x Earth's
=1000x Jupiter's
=99.9% of all mass in solar system |
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Term
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Definition
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Term
| The sun is the energy source that powers most surface processes on Earth including... |
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Definition
| wind, weather, most erosion, most biological processes |
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Term
| Sun's internal energy source |
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Definition
fusion of H to form He
some mass is converted to energy:
E=mc^2
energy is released in the form of gamma rays |
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Term
| Internal structure of the sun (from inside out) |
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Definition
| thermonuclear energy core, radiative zone, convective zone, photosphere (apparent surface) |
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Term
| What is the surface of the sun (photosphere)? |
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Definition
| lowest of sun's three main atmospheric layers; the region from which most sunlight escapes |
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Term
| the sun's magnetic field _______ polarity every 11 years |
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Definition
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Term
| the sun's activity is ______ |
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Definition
cyclical
11 yr sunspot cycle |
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Term
| How are estrasolar planets discovered? |
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Definition
1. radial velocity- star may appear to "wobble" about the centre of mass of the system
2. transits- planets pass in front of the star
3. excess infrared emissions- may indicate planets or protoplanetary disk |
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