TEST 2

solar nebula

a rotating cloud of gas and dust from which the sun and planets formed

gravitational collapse

- the rapid implosion of a star under its own gravitational forces

- The temperature of the solar nebula increases as it collapses

- As the cloud shrinks, its gravitational potential energy is converted to the kinetic energy of individual gas particles falling inward

Angular Momentum & Solar System

- The planets and moons rotations and orbits all rotate in the same direction, which is the direction of rotation of the original disk that formed them

- According to the solar nebula theory, our solar system was formed out of a huge cloud of gas and dust. Each of those gas and dust particles had some sort of random motion

Orderly Motions in Solar System

- Large bodies in the solar system have orderly motions and are isolated from each other

- All planets and most moons have nearly circular orbits going in the same direction in nearly the same plane

- The Sun and most of the planets rotate in this same direction as well

Cause of orderly motions

a collapsing gas cloud naturally tends to heat up, spin faster, and flatten out as it shrinks in size. thus our solar system began as a spinning disk of gas and dust. the orderly motions we observe today all come from the orderly motion of this spinning disk

Exceptions to orderly motion

- pluto

- most of the exceptions probably arose from collisions or close encounters with leftover planetesimals especially during the heavy bombardment that occured early in the solar systems history

Why are there two major types of planets?

Rock, metals, and ices condensed outside the frost line but only rock and metals condensed inside the frost line.

Small solid particles collected into planetesimals that then accreted into planets.

Planets inside the frost line were made of rock and metals.

Additional ice particles outside the frost line made planets there more massive, and the gravity of these massive planets drew in H and He gases.

asteriod

a solid, rocky and/or metallic body that independently orbits the sun.

Comets

a celestial object consisting of a nucleus of ice and dust and, when near the sun, a "tail" of gas and dust particles pointing away from the sun.

Origin of asteroids and comets

leftovers from the formation of our solar system 4.6 billion years ago. While the planets and moons have changed over the millennia, many of these small chunks of ice, rock and metal have not

age of solar system

4.6 billion years, radioactive dating

Chondrules

Small rocky bodies within the meteorites that may represent matter condensing from the original solar nebula. Meteorites are ALL 4.6 billion years old, or around there, the same age as earth.

Frost Line

the boundary in the solar nebula beyond which ices could condense; only metals and rocks could condense within the frost line

Extra solar planets + detection

a planet orbiting a star other than the sun

- transit method (Kepler): When a planet passes in front of its star, it's called a transit. As the planet transits in front of the star, it blocks out a little bit of the star's light. That means a star will look a little less bright when the planet passes in front of it

- radial-velocity method: relies on the fact that a star does not remain completely stationary when it is orbited by a planet. The star moves, ever so slightly, in a small circle or ellipse, responding to the gravitational tug of its smaller companion

Kepler Mission

determine how many earth-sized planets there are in or near the habitable zone using transit method

How to determine if extrasolar planet has life

- extremely large imagine telescope

interior of terrestrial planets

- the crust, a relatively thin region of low-density silicates

- mantle, a thick region of higher-density iron-rich silicates

- core, a central region of iron mixed with various impurities

How do the interiors of terrestrial planets get hot?

- Pressure

- Friction

- Radiation

What happens during planetary differentiation?

- process of separating out different constituents of a planetary body as a consequence of their physical or chemical behavior

- the denser materials of a planet sink to the center, while less dense materials rise to the surface, generally in a magma ocean

- Such a process tends to create a core and mantle

Why is planetary size so important to internal heat and geology?

- The greater the size, the longer a planet can retain enough internal heat to drive various geological processes (e.g., volcanic outgassing) which build up and maintain a dynamic hydrosphere.

- A large size also helps a planet retain atmospheric gases, which are gradually lost to space

What drives plate tectonics on Earth?

- mantle convection currents— warm mantle currents drive and carry plates of lithosphere along a like a conveyor belt

- ridge push, newly-formed plates at oceanic ridges are warm, and so have a higher elevation at the oceanic ridge than the colder, more dense plate material further away; gravity causes the higher plate at the ridge to push away the lithosphere that lies further from the ridge

- slab pull — older, colder plates sink at subduction zones, because as they cool, they become more dense than the underlying mantle. The cooler sinking plate pulls the rest of the warmer plate along behind it

Lunar Maria

the regions of the Moon that look smooth from Earth and actually are impact basins

- formed beginning about 3.9 billion years ago during a period of intense bombardment by asteroid-sized bodies

- most of the far-side basins were never flooded with lava to form Maria

What was the composition of the original atmospheres of Earth, Venus, and Mars?

- chemical reactions caused CO2 on Earth to dissolve in oceans and go into carbonate rocks (like limestone)

- H2O could exist in a liquid state

- N2 was left as the dominant gas

- O2 was exhaled by plant life- as the dominant gas on Venus, CO2 caused strong greenhouse effect

- mars lost much of its atmosphere through impacts

Loss of atmosphere on Mars

- Solar wind and radiation are responsible for stripping the Martian atmosphere, transforming Mars from a planet that could have supported life billions of years ago into a frigid desert world

Water on Mars

Used to have large oceans, now water found in subsurface ice.

What causes deserts?

rainshadow effect; 30 degrees effect

how many Hadley cells are there? (Equator to Pole)

1

Hurricanes in southern Atlantic

- sea surface temperatures that tend to run a shade cooler than ideal for tropical cyclone formation even in the southern summer,

- climatologically high values of vertical wind shear across that basin throughout the year

- lack of pre-existing centers of rotation (vorticity) in that area

How do you use craters to determine the age of planetary surfaces?

- counting # of impact craters

- the rate at which impacts have occurred in the solar system has been roughly constant for several billion years

Why isn't there much erosion on Venus?

- no wind, rain, or ice

- lack of weather is because the surface is very hot for liquid or ice to exist

- lack of wind is because Venus rotates very slowly

What happened to Venus about 500-800 million years ago?

- huge amount of gas was released into the atmosphere and couldn't be re-absorbed by the rocks

- made it uninhabitable

- period of intense volcanic activity, with magma solidifying on the planet's surface, suspending the cycle, and preventing the gas from being reabsorbed

What are the surfaces of Venus and Mercury composed of?

- terrestrial planets made of rock and metal

- Mercury is more dense than Venus and thought to consist of 60-70% metal, with the rest rock

Is Venus still geologically active?

- many volcanoes and domes of lava (corona)

- very active with tectonics and volcanism

- searing heat, heavy pressure, clouds of sulfuric acid, frequent volcanic eruptions

Why is Venus so hot?

- surrounded by a very thick atmosphere which is about 100 times more massive than our atmosphere here on Earth

- As sunlight passes through the atmosphere, it heats up the surface of Venus

What is the greenhouse effect?

the trapping of the sun's warmth in a planet's lower atmosphere due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.

Greenhouse effect on Venus, Earth and Mars

- Mars' atmosphere is composed mainly of carbon dioxide, but so little overall that the greenhouse effect is essentially negligible

- Earth, Mars, and Venus have similar atmospheres, interiors, surfaces, and similar greenhouse gases in the atmosphere

How do gyres effect hurricanes?

In perfectly blue ocean water, sunlight would penetrate deeper into the ocean. In the gyres, this heat would be taken away by subsurface currents, and so the surface would become cooler. Cooler surface waters would tend to produce less intense hurricanes.

What are the 4 unique features of Earth that are important to human life?

- liquid water, plate tectonics, and an atmosphere that shelters it from the worst of the sun's rays

How was the Moon created?

giant-impact theory

- Moon formed during a collision between the Earth and another small planet, about the size of Mars. The debris from this impact collected in an orbit around Earth to form the Moon.

What creates global wind patterns?

Earth's orbit around the sun and its rotation on a tilted axis causes some parts of Earth to receive more solar radiation than others. This uneven heating produces global circulation patterns. ... The air eventually stops rising and spreads north and south towards the Earth's poles

How does rotation effect the creation of Hadley cells?

Hadley cell brings the less dense, warmer air from the tropics and moves it toward the polar region

How is the Earth's atmosphere different now than it was 4 billion years ago?

When Earth formed 4.6 billion years ago from a hot mix of gases and solids, it had almost no atmosphere. The surface was molten. As Earth cooled, an atmosphere formed mainly from gases spewed from volcanoes. It included hydrogen sulfide, methane, and ten to 200 times as much carbon dioxide as today's atmosphere

How does the CO2 cycle promote climate stability on Earth?

Any change in the cycle that shifts carbon out of one reservoir puts more carbon in the other reservoirs. Changes that put carbon gases into the atmosphere result in warmer temperatures on Earth. ... This balance helps keep Earth's temperature relatively stable, like a thermostat

What happened to most of the CO2 in the Earth's atmosphere?

as life developed, CO2 was consumed so that by around 20 million years ago its concentration was down to below 300 molecules in every one million molecules of air

gases in Earth's atmosphere

- 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, and 0.1 percent other gases

- carbon dioxide, methane, water vapor, and neon are some of the other gases that make up the remaining 0.1 percent

Why isn't Florida a desert?

- bc it is a peninsula

- Surrounded by ocean moisture, Florida is an oasis sitting right in the middle of the desert belt, which traverses the subtropical latitudes north and south of the equator

What are monsoons?

seasonal wind patterns that cause wet and dry seasons

What are the major features of the Jovian planets?

- do not have solid surfaces

- composed primarily of hydrogen and helium, with traces of methane, ammonia, water, and other gases in their atmospheres

Why are Jovian planets so different from terrestrial planets?

- larger size and mass

- farther from sun, cooler

- less dense, made of gas

Do Jovian planets have Hadley cells?

no

What is the Great Red Spot?

- a storm in Jupiter's southern hemisphere with crimson-colored clouds that spin counterclockwise at wind speeds that exceed those in any storm on Earth

- slowly changed over the years, and is currently about 1.3 times as wide as our planet

How do other Jovian atmospheres compare to Jupiter's?

Jupiter's magnetosphere deflects solar wind and traps far more charged particles than Earth's. Saturn's magnetosphere is weaker than Jupiter's

How does the Earth's magnetic field protect the atmosphere?

- deflect most of the solar wind, whose charged particles would otherwise strip away the ozone layer that protects the Earth from harmful ultraviolet radiation

- One stripping mechanism is for gas to be caught in bubbles of magnetic field, which are ripped off by solar winds

What are three ways that a planet can lose atmosphere?

- thermal escape: molecular velocity due to thermal energy is sufficiently high

- non-thermal (or suprathermal) escape: photochemistry or charged particle (ion) interactions

- impact erosion: impact of a large meteoroid can lead to the loss of atmosphere. If a collision is sufficiently energetic, it is possible for ejecta, including atmospheric molecules, to reach escape velocity.

Why has Mars lost more atmosphere than the Earth?

- space due to solar wind and ultraviolet rays

active geology

An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years

Why do we suspect a subsurface ocean on Europa?

- Recent magnetic-field data from the Galileo orbiter showed that Europa has an induced magnetic field through interaction with Jupiter's, which suggests the presence of a subsurface conductive layer

- This layer is likely a salty liquid-water ocean

- Europa probably contains a metallic iron core

What makes Io so volcanically active?

Io is heated up by the strong gravitational pulls of Jupiter on one side and the large moons Europa, Ganymede, and Callisto on the other. This gravitational tugging stretches and bends Io causing it to heat up, much as a ball of clay warms up as you squeeze it repeatedly

Saturn's rings

- pieces of comets, asteroids or shattered moons that broke up before they reached the planet, torn apart by Saturn's powerful gravity. They are made of billions of small chunks of ice and rock coated with another material such as dust

How can planets migrate?

Planetesimal-driven migration

- orbit of a planet can change due to gravitational encounters with a large number of planetesimals

- If it is higher, for example a disk outside the planet's orbit, the planet migrates outward, if it is lower the planet migrates inward

How does conservation of momentum factor into planetary migration? Planetary migration theory

1. gas driven process in which the planetary disk effectively pushes or pulls the planet to a new position

2. the second arises as a result of gravitational interactions between neighboring bodies, where a large object can scatter a smaller one and thereby create an equal and opposite resulting force back onto itself

3. tidal forces, which mainly occur between the star and the planet and tend to result in more circular orbits

Which Jovian planets have ring systems?

All four jovian planets have rings, although only Saturn's rings are easily visible from Earth

What is the difference between a meteorite and a meteor?

- meteors: burning though Earth's atmosphere

- meteorite: landed on Earth

How do other ring systems compare to Saturn's?

rings of Saturn are made of much more reflective material (water ice) than those of Jupiter, Uranus or Neptune. They simply have much more matter in them

How do you identify a meteorite?

contain a significant amount of extraterrestrial iron and nickel, so the first step in identifying a possible meteorite is the magnet test. Iron and stony-iron meteorites are rich in iron, and will stick to a powerful magnet so strongly that it can be difficult to separate them

Why are so few meteorites found in Florida?

- The last time a meteorite was found in Florida was in 1983. While it is rare for meteorites to be found in the state, six of them were recently found near Lake City.

- The best hunting grounds are large, barren expanses where a dark rock — meteorites tend to be blackish — is easy to spot. Deserts, such as Southern California's Mojave Desert, and icy regions, such as Antarctica, are ideal

What are resonances in the asteroid belt?

Orbital resonances occurred where the orbital period of an object in the belt formed an integer fraction of the orbital period of Jupiter, perturbing the object into a different orbit; the region lying between the orbits of Mars and Jupiter contains many such orbital resonances

What is a Dwarf Planet?

- A dwarf planet is any object orbiting the Sun that is large enough to be round but not one of the 8 planets.

- has not cleared the neighborhood around its orbit and is not a moon

Why are there no large asteroid belts outside of Jupiter and inside of the Kuiper Belt

- most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. The Kuiper belt is home to three officially recognized dwarf planets: Pluto, Haumea and Makemake

What is the composition of comets?

- The solid nucleus or core of a comet consists mostly of ice and dust coated with dark organic material

- ice composed mainly of frozen water but perhaps other frozen substances as well, such as ammonia, carbon dioxide, carbon monoxide and methane.

- nucleus may have a small rocky core

What happens to a comet as it approaches the Sun?

- coma grows

- The solar winds push the dust and gas away from the coma causing them to stream off into space to form the comet's tail

- The solar winds cause the comet's tail to point away from the Sun

- Each time the comet passes close to the Sun, it loses some of its material

How do we know that vast numbers of comets reside in the Oort cloud and Kuiper belt?

By taking the size of the Oort cloud into account, and the number of long-period comets that have been seen, astronomers estimate that a staggering one 'trillion' (12 zeros) comets may be out there

What is the difference between the plasma tail and the dust tail?

The plasma tail is caused by an interaction between the solar wind and the cometary plasma, while the dust tail is by the solar radiation pressure to the cometary dust.

Why don't Pluto and Neptune collide?

Pluto's orbit takes it much higher above the Sun's orbital plane. When Pluto is at the same point as Neptune's orbit, it actually much higher up than Neptune. So the two planets will never be at the same place at the same time

Is Pluto a Kuiper belt object?

yes

Do asteroid/comets still collide with Earth?

asteroid or comet currently on a collision course with Earth, so the probability of a major collision is quite small. In fact, as best as we can tell, no large object is likely to strike the Earth any time in the next several hundred years

astrometric method

Gravity moves star / Consists of measuring a star's position in the sky and obersving the way its position changes over time / The detection of extrasolar planets through the side-to-side motion of a star caused by gravitational tugs from the planet

radial velocity method

Detects changes in frequencies of waves / a technique used to detect extrasolar planets by observing Doppler shifts in the spectrum of the planet's star

transit method

Planet passes in front / detecting exoplanets by observing the change in brightness as the planet eclipses the star.

Gravitational Microlensing

Gravitational lensing / Redshift or blueshift occurs from gravitational lensing / When a single nearby star passes between us and a distant object, it can cause gravitational lensing as well. But the effect is not large enough to produce separate images of the distant object. See exactly through center of parent star, gravity will bend starlight.

direct imaging

Directly images a planet / type of imaging system uses a solid-state sensor that contains an x-ray sensitive silicon chip with an electronic circuit embedded in the silicon, as the image receptor

astrometric method pros

many stars

astrometric method cons

only close stars, no terrestrial stars, slow

radial velocity pros

far stars

radial velocity cons

one star at a time, no terrestrial, slow

transit method pros

far stars, terrestrial planets, can determine the atmosphere

transit method cons

gravitational microlensing pros

terrestrial planets

gravitational microlensing cons

very rare, EXPENSIVE and sensitive instruments needed

direct imaging pros

can see planet

direct imaging cons

rare occassions, must be close to planet

doppler effect

observed change in the frequency of a wave when the source or observer is moving

blue shift is

approaching shift

red shift is

receding shift

Direct Detection

pictures or spectra of the planets themselves

Indirect Detection

Measurements of stellar properties revealing the effects of orbiting planets

We can detect planets by measuring the change in

a star's position on sky

Measuring a star's doppler shift can tell us its

motion toward and away from us

A transit is when

a planet crosses in front of a star

Eclipse

the planet passing behind the star