Astronomy Ch 6,7,8

tidal force

(differential force) variation in one body gravitational force from place to place across another body-- variation of moons gravity across the earth 7

planet building

1. condensation of solids 2.rocky planets formed from accretion 3.when large enough, called planetesimals 4.planetesimals grow through condensation and accretion--> protoplanets which are large enough to gravitationally influence other bodies 5. protoplanets grow through low speed collisions 6. Jovian planets built through gravitational collapse of gas onto large cores (if Protoplanet > 7 - 10 Earth masses): Core-accretion theory6

9 solar system properties

1. each planet is isolated in space 2.orbits of planets are nearly circular 3.orbits of planets lie in almost same plane 4.direction that planets orbit the sun is the same as direction in which sun rotates its axis 5.there is a chemical&density gradient from the inner&outer planets 6. Asteroids are very old and most of material we expect is missing 7.Kuiper Belt collection of rocky body 8.oort cloud comets are primitive, rocky-icy bodies that do not orbit in plane of solar system 9. there is a apparent period of late heavy bombardment shortly after formation of planets 6

Mercury is never seen farther than (?) degrees away from the sun

28

what is mercurys spin orbit resonance

3:2- spins 3 times around its axis for every one rotation around sun it is caused by tidal interactions with the Sun and the fact that it has an highly eccentric orbit making it "tidally lock" to it's rotation at perihelion

greenhouse gases

gases that absorb infrared radiation efficiently 7

comets

generally icy rather than rocky in composition (although they do contain some rocky material) and diameters in 1-10 km range 6

what radioactive elements melt planets from inside out?

iron 60 and aluminum 26 7

moons rotational period is equal to

its orbital period (27.3 days)- synchronous orbit moon is tidally locked to earth

atmosphere

layer of gas confined close to a planets surfaces by a force of gravity 7

lunar highlands

light part on moon more craters 8

regolith

lunar dust that covers moon, what astronauts leave footprints in 8

capture theory

maintains that moon formed far from earth and was later captured by it 8

parts of earths interior

mantle, crust, inner core, outer core 7

density

measure of the "compactness" of matter. Average density is computed by dividing an objects mass by its volume 6

smallest and largest planet?

mercury and jupiter 6

order of planets

mercury venus earth mars jupiter saturn uranus neptune 6

condensation nuclei

microscopic platforms to which other atoms can attach, forming larger and larger balls of atoms 6

seismic waves

move outward from the site of the quake. like all waves they carry info 7

fragmentation

the breaking up of a large object into many smaller pieces 6

protosun

the central accumulation of material in the early stages of the solar system 6

convection

the constant upwelling of warm air and the concurrent downward flow of cooler air to take its place, a process that physically transfers hear from a lower (hotter) to a higher (cooler) level -transfer of heat from one place to another through movement of gas or liquid 7

accretion

the gradual growth of small objects by collision and sticking 6

gravitational instability theory

the jovian planets formed directly from the nebular gas, skipping the initial condensation-and-accretion stage and perhaps taking no more than a thousand years to acquire much of their mass 6

condensation theory

the model favored by most astronomers-- rests squarely on the old nebular theory, combining its basic physical reasoning with new information about interstellar chemistry to avoid most of the original theory's problems 6

midocean ridges

the plates are moving apart, as they recede, new material from the mantle wells up between them 7

radioactivity

the release of energy by certain rare heavy elements, such as uranium, thorium, and plutonium 7

synchronous orbit

the spin of one body is precisely equal to its revolution around another body 8

solar system

the sun and all the bodies that orbit it-- mercury venus earth mars jupiter saturn uranus neptune, their moons, the asteroids, and the comets 6

solar nebula

the swirling gas surrounding the early sun during the epoch of solar system formation, also referred to as primitive solar system 6

lithosphere

the tectonic plates. contains both the crust and upper part of mantle. portion of earth that undergoes tectonic activity 7

angular momentum

the tendency of a body to keep spinning or moving (like figure skater) 6

dynamo theory

theory that explains planetary magnetic fields in terms of rotating, conducting material flowing in the planets interior 7

core-accretion theory

theory that the jovian planets formed when icy protoplanetary cores became massive enough to capture gas directly from the solar nebula 6

what portion of the atmosphere do we live in?

troposphere 7

list of the different parts of the atmosphere from low altitude to high altitude

troposphere(weather and convection), stratosphere(ozone layer and where planes fly), mesosphere, ionosphere 7

resonance

two characteristic times are related to each other in a simple way 8

which planet is tipped over

uranus6

differentiation

variation in the density and composition of a body, such as earth, with low density material on the surface and higher density in the middle 7

plate tectonics

well defined lines of activity where crustal rocks dislodge (earthquakes) and mantle material upwells (volcanoes). created mountains and other large scale features 7

lunar composition and structure

Overall: Very similar to Earth's mantle Very small iron core compared to the Moon's overall size Lunar far-side crust about 2x as thick as near-side

giant impact theory

a collision by a large Mars-sized object hit earth and dislodged from our planet creating the moon 8

rille

a ditch where molten lava once flowed 8

solar wind

a stream of energetic charged particles that continually flows outward from the sun and pervades the entire solar system 6

jovian planets

all orbit far from the sun, no solid surfaces and their outer layers are predominantly composed of the light gases hydrogen and helium- jupiter saturn uranus neptune 6

asteroid and meteoroid difference

anything larger than 100m in diameter is asteroid anything smaller is a meteoroid 6

why are scientists concerned about greenhouse gases?

because of the greenhouse effect and that since the Industrial Revolution, there has been a well-documented increase in atmospheric CO2 levels beyond what has ever been observed in any natural cycle7

craters

bowl shaped depressions that are caused most likely by giant impacts 8

scarp

cliff on mercury 8

climate vs weather

climate- desert, "we get hurricanes here" weather-short time scale phenomena

comparative planetology

comparing and contrasting the properties of the diverse worlds we encounter 6

convection cells are responsible for

contribute to atmospheric heating and responsible for surface winds 7

what drives plate tectonics?

convection in semi solid mantle aka asthenosphere the crust and upper part of the mantle that make up plates is the lithosphere 7

what two factors make up a magnetic field through a dynamo?

convection of a conducting liquid sufficiently fast rotation period (less than 10 days) 7

what process is responsible for the enormous forces that drag the plates apart in some locations and together in other

convection7

interplanetary matter

cosmic debris ranging in size from the relatively large asteroids and members of the Kuiper belt, through the smaller comets and even smaller meteoroids, down to the smallest grains of interplanetary dust that liter our cosmic environment 6

tides

daily fluctuation in ocean level generated by tidal force 7

lunar maria

dark part on moon 8

which of the terrestrial planets have moons?

earth and mars 6

tidal bulge

elongation of earth caused by the difference between the gravitational force on the nearest side of the moon and the force on the farthest side of the moon. the long axis of the tidal bulge points toward the moon. more generally, the deformation of any body produced by the tidal effect of a nearby gravitating object 7

how old is the moon?

Cratered Highlands (4.4i Gya) and Maria (3.9 - 3.2 Gya)

do jovian or terrestrial planets have stronger magnetic fields

JOVIAN terrestrial magnetic fields are very weak compared to them6

Mercury composition and interior

Largest iron core with respect to Mercury's overall size

van allen belt

one of at least two donut shaped regions of magnetically trapped, charged particles high above earths atmosphere 7

nebular theory

one of the earliest models of solar system formation, dating back to Descartes, in which a large cloud of gas began to collapse under its own gravity to form the sun and planets 6

ozone layers

one of the insulating spheres that serve to shield life on Earth from the harsh realities of outer space 7

subduction zones

one plate slides under the other, ultimately to be destroyed as it sinks into the mantle. they are responsible for the deep trenches in the ocean 7

karmen line

outer space boundary 7

greenhouse effect

partial trapping of solar radiation by a planetary atmosphere, similar to the trapping of heat in a greenhouse 7

aurora

particles from van allen belts escape from magnetosphere near earths north and south magnetic poles where the field lines intersect the atmosphere. their collision with air molecules create the lights. they result with atmospheric molecules, excited among collision with the charged particles, fall back to their ground states and emit visible light 7

terrestrial planets

planets that lie within 1.5 AU from the sun, all are small and of relatively low mass, generally rocky composition and solid surfaces(mercury venus earth mars) 6

p waves

pressure waves- first to arrive at monitoring site. expand and compress the medium (the core and mantle) can travel through liquid and solid 7

rock cycle

process by which surface rock on our planet is continuously redistributed and transformed from one time into another 7

magnetosphere

region around a planet that is influenced by a planets magnetic field 7

intercrater plains

regions on surface of mercury that do not show excessive cratering but are relatively smooth 8

why is sky blue?

scattering of light, such that shorter wavelengths (bluer light) are more efficiently scattered than longer wavelengths (redder light) 8

asthenosphere

semisolid part of mantle over which the lithosphere slides 7

s waves

shear waves- vibrate the material through which they pass back and forth along the direction of travel of the wave, cause side to side motion, more like waves on a guitar string. can't travel through liquid 7

daughter or fission theory

speculates the moon originated out of the earth itself 8

sister, or coformation theory

suggests that the moon was formed as a separate object near Earth in much the same way as our own planet was formed 8

planetesimals

term given to objects in the early solar system that had reached the size of small moons, at which point their gravitational fields were strong enough to being influencing their neighbor 6

which has higher density, terrestrial planets or jovian planets?

terrestrial 6

protoplanets

the accumulations of matter that would in time evolve into the planets we know today 6