Unit 9 Formation of the Solar System and Terrestrial Planets

jumbled terrain

-opposite of Caloris Basin on Mercury -other side of planet -jumbled land by seismic waves from the impact

Microlensing

estimates mass of planet

heavy bombardment

event of intense meteor impacts -leftover planetesimals hit other objects in the late stages of the solar system

Caloris Basin

largest impact crater on Mercury (largest basin); created jumbled terrain on opposite side; close-up pictures show stretch marks from surface rebounding

Nebular hypothesis

our solar system formed from the gravitational collapse of a giant interstellar gas cloud

Transit

planet must pass in front of the star (a tough requirement) - can reveal planet's size/radius

Magnetosphere

the region surrounding the earth or another astronomical body in which its magnetic field is the predominant effective magnetic field. -protects atmosphere from solar wind -field lines channel solar wind particles into poles -sun-facing end is flattened -other end has a tail

Protostar

the second stage of a new born star in a nebula. A new star is born because when the nebula contracts, it becomes are dense and hot and this is how a star is born and is on its first stage. The prostar is it second stage

Direct imaging

very tough to block out the glare from the star - only good for large planets orbiting at large distances from their star

Primary Atmosphere

- an atmosphere of a planet that forms by accretion of gaseous matter from the accretion disc of the planet's sun. Planets such as Jupiter and Saturn have primary atmospheres. Primary atmospheres are very thick compared to secondary atmospheres like the one found on Earth. -more primitive

Dynamo theory

-A strong magnetic field will be produced if a planet has a liquid core and relatively fast rotation

Accretion

-For planetesimals: Many smaller objects collected into just a few large ones. -In Jovians: collection of rocky/metallic materials could have formed an terrestrial core During Heavy Bombardment: collection of leftover planetesimals bombarded other objects in the late stages of solar system formation -Also happens when planets are young

Lobate Scarps

-On mercury -Curved cliffs, probably formed when Mercury shrank while cooling down

Lunar Maria

-On near side only -Basaltic Formation: -Early surface is covered with craters. -Large impact crater weakens crust. -Heat build-up allows lava to well up to surface. -Cooled lava is smoother and darker than surroundings.

Solar Wind

-Particles released from the sun -the continuous flow of charged particles from the sun that permeates the solar system.

Valles Marinaris

-System of valleys on mars -thought to originate from tectonics

Accretion Disc

-formed by diffused material in orbital motion around a massive central body. The central body is typically a star. Gravity causes material in the disk to spiral inward towards the central body. -conservation of angular momentum -flattening

Olympus Mons

-largest volcano in solar system -on Mars -whole Mon appears to have been lifted (sheer cliffs)

Lunar Highlands

-on the dark side of the moon -no maria -crust is thicker(from wrinkling?)

bow shock

-on the sun facing side of the magnetosphere -flattened -blocks/directs solar wind particles towards field lines to the poles??

Pancake Domes

-on venus -evidence of volcanism -Associated with volcanic activity forming coronae

thermal escape

Cause of loss of gas on surface of planets

Oort Cloud

Contains about 1 TRILLION comets. These comets were likely "flung" there by the Jovian planets during late Solar System formation. About 50,000 AU from the Sun (average distance). HIGHLY elliptical orbits

Frost line

Inside: too hot for hydrogen compounds to form ices Outside: cold enough for ices to form Between Mars-Jupiter

Angular Momentum

L = mvr Rotation speed of the cloud from which our solar system formed must have increased as the cloud contracted

Detecting an exoplanet

Methods of Detection: -Doppler Shifts - can reveal planet's mass/orbital distance -Transit - planet must pass in front of the star (a tough requirement) - can reveal planet's size/radius -Microlensing - estimates mass of planet -Direct Imaging - very tough to block out the glare from the star - only good for large planets orbiting at large distances from their star

crater dating

More craters = older surface; less craters = younger

Surface Ejection

Probably stuff that was ejected into space by impacts

Condensation

Temperature in the protostellar cloud decreased outward. Denser materials collect and condense closer in towards the protostar. Lighter, more volatile materials only condense further out from the protostar.

planetismal

a minute planet; a body that could or did come together with many others under gravitation to form a planet.

exoplanet

a planet that orbits a star outside of the solar system

Hadley circulation

a tropical atmospheric circulation that features air rising near the equator, flowing poleward at 10-15 kilometers above the surface, descending in the subtropics, and then flowing equatorward near the surface. -earth has six convection cells

Secondary atmosphere

an atmosphere of a planet that did not form by accretion during the formation of the planet's star. instead forms from internal volcanic activity, or by accumulation of material from comet impacts.

differentation

any process in which a mixture of materials separates out partially or completely into its constituent parts, as in the cooling and solidification of a magma into two or more different rock types or in the gradual separation of an originally homogeneous earth into crust, mantle, and core.

Doppler shifts

can reveal planet's mass/orbital distance

Scattering

change in photon's direction