ERTH 101 Study Guide for Exam 2 PDF

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ERTH 101 Study Guide for Exam 2

Chapter 5 The Architecture and Birth of Planetary Systems Know the definition of these terms: 

Kuiper Belt Object (KBO): a small body made of ice and rock that orbits beyond Neptune’s orbit in the Kuiper.

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Exoplanet: a planet orbiting any star other than the Sun

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Dwarf Planet: a body that orbits a star and has enough mass to become spherical by self-gravity but that has not cleared its neighboring region of small objects (Pluto)

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Asteroid Belt: the disk-shaped region, between Mars and Jupiter, where many asteroids orbit (from 2.1 – 3.5 AU)

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Kuiper Belt: the disk-shaped Solar System zone outside Neptune’s orbit, from 30 – 50 AU, containing small bodies made of ice and rock

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Scattered Disk: disk-shaped region beyond the Kuiper Belt that contains many small bodies made of ice and rock. Their highly elliptical orbits may reach perihelion as low as 30 AU and aphelion as high as 100 AU

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Oort Cloud: a spherical region at the outer limits of the solar system with a radius of approx.. 50,000 AU, believed to contain potentially trillions of comets

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Terrestrial planet: a planet consisting primarily of solid material, made mostly of iron, nickel, and silicate rock. (Mercury, Venus, Earth, Mars)

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Gas giant: a planet consisting of mostly hydrogen and helium that has a mass many times that of Earth (Jupiter and Saturn)

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Ice giant: a planet consisting of mostly ices - water, methane, CO2, CH4, and other compounds (Uranus and Neptune)

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Uncompressed density: the density an object would have if the effect of gravity were excluded

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Planetesimals: an irregular rocky object, typical of those from which planets are believed to have formed by accretion. (EX: asteroid or KBO)

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Trojan asteroids: co-orbiting asteroids around Jupiter with one group preceding the planet at a specific distance and the other group following Jupiter at the same distance (found at L4 and L5 Lagrange points)

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Lagrange points: when the gravitational force from two bodies are considered together, the Lagrange points are places where an object may orbit with a stable orbit. (planet and sun)

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Earth crossing asteroids (ECAs): an asteroid whose highly elliptical orbit crosses Earth’s orbit and is therefore a potential risk for collision with Earth

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Differentiation: the processes in planet formation whereby, during a planet’s molten stage, the denser materials link to the center where less dense materials rise to the surface, forming distinct layers.

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C-type asteroids: an asteroid that is rich in carbon and typically dark – raw material that never combined with other material to create a larger body (carbonaceous)

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S-type asteroids: an asteroid that contains mostly silicate rock and is typically more reflective than C-type asteroids are (silicone and oxygen) – most common, 75% of all asteroids

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M-type asteroids: came from the core – they are metal type asteroids

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Snow line: the distance from the sun or other star beyond which it is cold enough for water to exist as ice (about 4.5 AU)

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Albedo: the reflecting power of an object, measured as the ratio of light reflected to light received (high = bright, low = dark)

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Comet Nucleus: the main body of a comet, the core, composed of rock and ice

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Comet Coma: the nebulous envelope around the nucleus of a comet, formed when the comet passes close to the sun (comets do not always have a coma, only once the come close to the sun) – the solid turns directly into a gas (sublimation) – no coma at aphelion!

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Comet Ion Tail: the tail of a comet that is composed of gas and reacts to the solar wind, thus always points directly away from the sun. (the straight portion of the tail – points directly away from the sun)

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Comet Dust Tail: composed of small grains of solid matter blown off the nucleus, driven off by solar radiation and always points away from the sun. (tends to curve)

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Short-period comet: a comet that originated in the Kuiper Belt or scattered disk and has an orbital period of 200 years or less

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Long-period comet: a comet that originated in the Oort cloud and has a highly eccentric orbit and an orbital period from 200 years to millions

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Rosetta Mission: a mission from the ESA to Churyumov Gerasimenko (67P)– had a lander called Filee, stayed with comet from aphelion to perihelion, then it crashed into the surface of the comet.

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Churyumov Gerasimenko (67P) :The water on the comet was different from the water on Earth.

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Meteoroid: a rock ranging in size from a grain of sand to a boulder and orbiting the sun – could potentially fall through the atmosphere of earth

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Meteor: a meteoroid that has entered Earth’s atmosphere. Heat from friction causes radiation that may be seen as a very brief streak of light or as a fireball (shooting star)

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Meteorite: a rock that was a meteoroid, then a meteor, and has reached Earth’s atmosphere

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Bolide: something that blows up as it is flying through the atmosphere

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Meteor shower: the appearance of frequent meteors, over a period of a few hours or several days. Occurs at fixed times each year. The source of the showers is debris material blown off comets. As the Earth passes through a trail of debris from a comet.

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Interstellar gas: ionic, atomic, or molecular gas found in diffuse clouds in the regions between the stars – this is what stars form from.

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Center of mass: the point around which two orbiting bodies move. It lies closer to the more massive of the two objects. If the masses are the same it lies between the two bodies.

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Radial velocity method: an exoplanet detection method that measures changes in a star’s velocity as it orbits a common center of mass with one or more planets (the redshift/blueshift method) – good for finding hot Jupiter’s

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Transit method: an exoplanet detection method that measures changes in the brightness of a star as a planet passes in front of it

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Kepler space telescope: launched in 2011, uses the transit method to locate planets – it is watching the light curve of a star

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Super-Earth: a planet with a mass greater than Earth’s but substantially less than 15 Earth masses

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Habitable zone (Goldilocks Zone): the region around a star where liquid water can exist on the surface of a planet – not too close, not too far

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Hot Jupiter: a Jupiter-sized planet orbiting very close to its star, usually at a fraction of an AU

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Conservation of angular momentum: if you take a large star mass, closer to the mass gets faster orbit

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Condensation theory: a theory of planetary formation in which planets are created from a disk of gas and dust around a newly formed star

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Protoplanetary disk: the disk that surrounds a young star, from which planets may form – the proto-star is in the middle, it is not a star yet as it has not ignited, it is hot because of the conversion of gravitational potential energy forming to thermal energy

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Interstellar dust grain: tiny bits of solid matter found in diffuse clouds in the regions between star

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Geostationary Satellite: orbits the Earth, has the same period of Earth’s rotation

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Core accretion model: a model of giant gas planet formation in which an icy terrestrial planet grows by binary accretion up to a critical point and then rapidly pulls gas in from the surrounding disk – in order for planets like Jupiter and Saturn to form, you had to first make a core, then gather together hydrogen and helium.

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Hydrodynamic Instability Model: a model of giant gas planet formation in which small regions collapse to form planets within a gravitationally unstable disk.

Be able to:  Determine from the period of the comet where the comet probably originated.

o > 200 years = Kuiper Belt o < 200 years = scattered disk or Oort Cloud 

Identify the ion and dust tail of a comet from an image o Ion tail = straight line pointing directly away from the sun, brighter color o Dust tail = curved

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What o o o

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Explain using the condensation theory how the different planets in our solar system came to have differing compositions. o Heavier materials “sink” and formed into the center, lighter materials expand outward, creating gas and ice planets o Condensation Sequence: Protostar is formed -> space of nothing -> Metal oxide -> Silicate -> Water Ice -> Other kinds of ices (CO2, Nitrogen Oxide, Methane)

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Describe how the principle of conservation of angular momentum is applied to solar system formation as well as the movement of the planets in the solar system. o Condenses and collapses, rotating faster and flattening into a disk o Believe that some of the planets formed and then migrated due to some form of interaction or exchange of energy and momentum o Objects closer to the sun will move faster o Original spherical gas cloud that formed our solar system was approx. 1 ly wide

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Estimate the location of the Center of Mass for two masses, if they are the same or different. o If object masses are the same, the center of mass is directly between the two objects o If object masses diff, the center of mass is closer to the larger mass object, which creates one small, slow orbit for the larger mass, and a larger, faster orbit for the smaller mass o This impacts redshift and blueshift. Redshift the object is orbiting away, blueshift the object is orbiting closer

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Explain the activity of a comet on its elliptical orbit around the sun. o A comet always has a tail closer to the sun (perihelion) o The further away from the sun the comet goes, the less tail it has

is Trappist 1? System with 7 habitable-zone planets Has a red dwarf star * All 7 planets orbit the star within the same distance as Mercury orbits our Sun

o The ion portion of the tail points directly away from the sun, while the dust portion makes a curve (but also points away from the direction of the sun) 

Explain the heating and light that are seen when a meteor streaks through the atmosphere. o As the meteor enters or comes close to the atmosphere, it creates a tail of debris o We see light of the tail because of the grains of sands that leaves a streak due to the energy – we see light because of the atmosphere which is heating up o It heats up as it enters the atmosphere because compressional heating – when you compress a gas, it gets hot, as a meteor comes into the atmosphere, it compresses a lot of gas = heat energy = light from the air molecules

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Explain how M-type and S-type asteroids probably form. o A protoplanet smashed together o The inner layers became M-Type (metal) o The outer layers became S-type (silicate)

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Describe how the different methods of exoplanet detection work: direct imaging, radial velocity and transit method. Which one is the best? o Direct imagining: pictures taken of planets/stars o Radial Velocity: the doppler effect (redshifts and blueshifts) o Transit: measures changes in the brightness of a star as a planet passes in front of it o Transit is the best method

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Explain why the recent discovery of 7 habitable planets around Trappist-1 is so exciting. o 3 of those planets are in the habitable zone o We can find planets now that may be “Earth-like” – could have liquid water

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Describe the Hyabusa2. Where did it land? What did it achieve? o It landed on the asteroid “Ryugu” – goal was to collect specimens from the asteroid. The robots “hopped” around like bunnies due to lack of gravity o A sample return mission

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What is the Starcatcher? o A satellite whose mission was to catch comet dust – the 1st mission was successful, crash landed but the dust that was collected survived the crash

Memorize:  The locations of the planets and the asteroid belt, Kuiper belt, scattered disk and Oort cloud in order of their distance from the sun o Mercury, Venus, Earth, Mars, Asteroid Belt, Jupiter, Saturn, Uranus, Neptune, Kuiper Belt, Scattered-Disk, Oort Cloud  The Lagrange positions for two gravitational bodies.

Chapter 6 Earth and the Moon Know the definition of these terms: 

Radioactive Decay: process by which an unstable atom in a higher energy state, which will find a lower energy state, transforms into a new element by releasing some form of radiation

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Half-life: time it takes for half of whatever radioactive material to decay, the other half will remain radioactive, the decayed half will transform to

stable material. Continue to halve the radioactive material. (16-8-4-2-1) (0-8-12-14-15) 

Core: Earth’s innermost layer, composed primarily of iron (under pressure so it becomes solid). The inner core is solid; the outer core is in a fluid molten state

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Mantle: the layer of molten rock between Earth’s core and crust, composed of silicate rocks. High pressure in the mantle cause material to deform and flow

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Lithosphere: Earth’s solid outer layers, consisting of the crust and uppermost regions of the mantle.

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Crust: Earth’s solid outer layer (crust = 30 – 50 km/ 20 miles thick )

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Basalts: a type of dark, high-density volcanic rock that forms by the quick cooling of magma at the ocean floor making the oceanic crust (70% of Earth is water)

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Granite: a lower density silicate, together with basalt makes the crust. The continental crust is comprised of granite.

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Seismic waves: a propagating wave in Earth’s interior, caused by an earthquake or volcano.

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P-waves: (primary) a seismic wave in which atoms and molecules oscillate back and forth in the same direction as the wave’s propagation. This is a longitudinal pressure wave (faster)

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S-waves: (secondary) a seismic wave in which atoms and molecules oscillate perpendicular to the direction of the wave’s propagation. This is a transverse shear wave

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Heat transfers: see below

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Conduction: inner core to outer core, solid touching another material, transfers heat energy as they touch

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Convection: the transfer of heat from one place to another by fluid motion

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Radiation: when the Earth’s heat energy escapes into space – cools Earth

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Plume: molten rock from a planet’s mantle that breaks through the crust (the magma that flows)

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Shield volcano: a volcano formed from a mantle plume that tends to have shallow, sloping sides – formed layer by layer

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Plate tectonics: the movement of Earth’s crustal plates due to underlying mantle flow; continental collisions, subduction, hotspot, spreading center, transform fault (plates rub across each other creating earthquakes (San Andres Fault)

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Continental collision: builds mountains (the Himalayas), the Appalachian mountain range

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Subduction: a geologic process in which one edge of a crustal plate is forced below the edge of another. Continental crust remains on top as it is less dense than the oceanic crust

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Spreading Center: two crusts are moving away from each other; magma rises and fills the gap – Mid-Atlantic Ridge

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Hotspot: weaker spot in the curst where magma can form a volcano, but in hotspots you get a chain of volcanic activity - Hawaiian Islands, Yellowstone,

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Troposphere: the lowers layer of Earth’s atmosphere, reaching a maximum altitude of 17 km; the location of most of Earth’s weather and clouds, most of the water is located here

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Stratosphere: The Earth’s second level of atmosphere, extending from about 20-50km, ozone layer is located here

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Mesosphere: the third level of Earth’s atmosphere, extending up to 85km

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Ionosphere: the fourth level of Earth’s atmosphere, extending up to 1,000kmm where most of the atoms are ionized - it is electrical from charged particles, electrically active

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Ozone: a molecule composed of three oxygen atoms: O3 – blocks majority of ultraviolet rays from the Sun

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Greenhouse effect: the fraction of incoming solar energy that would have been radiated back into space is trapped by greenhouse gasses, leading to an increase in the average temperature of the planet. Sunlight in the form of visible light can come into the atmosphere, but once it is

absorbed by the earth, it is reradiated in the form of infrared, and is trapped by the water, Cos and methane in the atmosphere – too much means a hot Earth and an unstable environment 

Magnetosphere: a region of space around a planet where the planet’s magnetic field exerts a strong force –it protects us from the solar winds

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Magnetic Dynamo effect: the flow of electrically charges fluid inside a body, that can generate a large-scale magnetic field in a planet, star, or any other astronomical object. Circulation of charged matter, electric currents create a large magnetic field

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Solar wind: a stream of energetic, charged particles flowing off of the sun – mostly electrons

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Aurora: the solar wind hits the magnetic field of the earth, charged particles spiral around the magnetic field, giving off their energy to the atmosphere which begins to glow. The particles do not glow, the atmosphere glows as it becomes energized.

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Aurora Borealis: aurora in the north “northern lights”

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Aurora Australis: aurora in the south “southern lights”

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Tides: a twice-daily change in the local height of sea level; with regular modulations over periods of months to a year. The Moon is more important that the Sun in its effect on Earth’s tides.

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Tidal force: force acting on an object that is due to differential gravity from a second object – the difference in the force of gravity between the near side and the far side of a body

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Spring tides: a tide that is greater than average because it is reinforced by the linear alignment of the Sun, Earth, and Moon at the new and full moon phases – both the Sun and Moon are pulling on the Earth in the same direction, stretching the Earth creating higher than normal tides

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Neap tides: a tide that is less than average because of the Sun’s gravity partially cancelling out the Moon’s gravity at 1st and 3rd Quarter phases

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Tidal locking: the one-to-one relationship between the rotation and revolution periods of an orbiting body that is created by tidal effects, such that the orbiting object always shows the same...