ISP 205 Exam 2

Describe the major patterns we find among objects orbiting the Sun.

-Terrestrial planets: rocky planets
-Jovian Planets: gaseous planets
-Asteroid belt between Mars and Jupiter
-Kuiper belt past Neptune full of ice balls and comets
-Dwarf planets orbit past Neptune
-All rotate counterclockwise

Predict how the temperature of an opaque gas cloud will change as the cloud shrinks

As it shrinks its temperature will increase (conservation of energy)

Explain how the nebular theory accounts for the dependence of planetary composition on distance from the Sun

-As the cloud forms disks when it spins, inner disks (within the frostline) are hotter than the outer
-Rocks are solidified at higher temperatures than ice
-Inside the frost line it's too hot for hydrogen to form ice
-Outside frost line it's cold enough for ice to form

Distinguish between terrestrial planets, jovian planets, and dwarf planets.

-Terrestrial planets: rocky planets (C, O, Si, Fe), few moons
-Jovian Planets: gaseous planets (H, He, hydrogen compounds), many moons
-Dwarf Planets: large dirty balls of ice

Identify the major bodies of the solar system from their characteristics.

-Sun: 99.8% of mass in SS
-Mercury: hot rock
-Venus: cloudy, thick atmosphere, very hot
-Earth: watery "double planet"
-Mars: frozen rocky planet with possible ice
-Jupiter: gaseous planet
-Saturn: gaseous with rings
-Uranus: tilted sideways, gaseous
-Neptune: same size a Neptune, rings, gaseous
-Pluto: dirty ball of ice, moon is same size
-Comets: far end of solar system, elongated orbits

Describe the nebular theory for solar system formation.

-Gravity pulls cloud of gas in, making it heat up and spin faster (conservation of energy and angular momentum)
-Cloud flattens into a rotating disk as it speeds up
-Objects form in disk (planets and asteroids and comets)
-Tiny particles stick together forming planetesimals
-Accretion draws planetesimals together forming planets
-All objects rotate in the same direction and form based on location (terrestrial and Jovian)

Explain how the nebular theory accounts for the motions of planets and their moons.

They all rotate in the same direction (counterclockwise) because of the spinning disk of particles that formed them

Predict how the locations of terrestrial and jovian planets would change if the temperature of the solar nebula had been different.

-If it was warmer, there would be more terrestrial planets because rock could form
-Colder temps mean more Jovian planets because ice can form

Explain how the nebular theory accounts for the existence of asteroids and comets

Solar wind blows all excess gas into space and they form from leftover planetesimals that remain

Explain how the nebular theory accounts for exceptions to the usual patterns.

-Moon: Large impact of a planetesimal blew a chunk out of Earth
-Rotations: Impacts could cause the planets to flip over (Venus and Uranus)

Explain how radiometric dating has been used to establish the age of the solar system.

We measure elements in meteorites and how they are decaying and turning into different elements over half-lives

Arrange planetary surfaces in order of increasing age based on the level of impact cratering

The more cratering and erosion on craters, the older it is

Explain why Earth's sky is blue and its sunsets are red.

-Sky is blue when particles of sunlight are scattering blue through the atmosphere
-Sunset is when sunlight travels a longer path through the atmosphere, when only red/yellow light remains to scatter (longer wavelengths)

Describe the evidence that water once flowed on the surface of Mars.

-Surface has dried up riverbeds
-Craters show erosion on surface
-Altitude maps show low-lying regions at the poles and throughout (blue regions show water ice potential)

Explain why Venus is so much hotter than Earth.

-It has a much thicker atmosphere, causing a more intense greenhouse effect
-It is much more reflective than Earth, so it shouldn't absorb more sunlight, but the atmosphere makes it absorb a lot

Discuss the primary features that make a terrestrial planet habitable.

-Cycles of elements
-Greenhouse effects

Explain how Earth's carbon cycle keeps its climate stable.

-It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate.
-CO2 dissolves in the ocean and trapped in rocks
-Rainfall erodes those rocks
-CO2 releases into atmosphere through plants, volcanism, and plants

Describe the scientific evidence indicating that human activity is causing global warming.

-Carbon dioxide concentration in the atmosphere is increasing but not from plant cycles
-Average surface temperature, growing seasons, and movement north is increasing

Identify the most likely locations for life among the jovian moons.

-Jupiter's Europa has a possible ocean under the ice covered surface
-Saturn's Enceladus has ice volcanoes

Describe how a terrestrial world's size affects its level of geological activity and the strength of its magnetic field.

-The higher the mass of the planet, the greater the amount of energy deposited on it during formation, the greater the heat and, therefore, the greater the amount of tectonic activity
-The greater the size, the longer a planet can retain enough internal heat to drive various geological processes
-The larger the planet, the stronger the magnetic field is

Distinguish between planetary surface features produced by impact cratering, volcanism, tectonics, and erosion.

-Volcanoes come up in the middle
-Tectonics are lines that look like the planet is splitting
-Craters are circular impacts in the surface
-Erosion is when it looks smooth

Describe how Earth's atmospheric layers are related to the absorption of radiation from space.

The atmosphere absorbs most radiation besides radio waves, some infrared, and visible light

Predict how a planet's reflectivity would affect its surface temperature.

The more reflective, the colder its temperature would likely be

Describe how greenhouse gasses trap heat and increase the surface temperatures of terrestrial planets

Molecules such as H2O, CO2, and CH4 trap infrared photons in the atmosphere from escaping, heating up the surface

Describe the evidence indicating the history of geological activity on Mars.

-Thin CO2 atmosphere shows weather occurring on Mars
-Has seasons where polar caps freeze more in winter months

Explain why the geological features of Mars indicate that a stronger greenhouse effect kept its surface substantially warmer several billion years ago.

Lots of volcanoes erupted 3 billion years ago releasing a lot of CO2 but they stopped erupting so the atmosphere has thinned out over time

Distinguish between evidence of a correlation and evidence of causation in the context of global warming.

-Observations of changes in quantities don't prove causations
-We need models to be able to test causation
-Measuring amount of radiation reflected, incoming, absorbed, and emitted

Describe the interior structure of a jovian planet.

-Jupiter & Saturn: Hydrogen and Helium
-Uranus & Neptune: Hydrogen compounds (H2O, CH4, NH3), Hydrogen, Helium, and some rock
-Core of rock, metal, hydrogen compounds (hot and dense)
-Metallic hydrogen above, then liquid, then gas hydrogen clouds

Identify the physical characteristics of the major jovian moons

-Icy balls like Pluto
-Large moons are rounder than smaller irregular shaped moons
-Jupiter moons:
*Io: active volcanoes and young surface
*Europa: young icy surface with possible ocean beneath surface
*Ganymede: cratered and younger regions
*Callisto: Oldest, heavily cratered surface
-Saturn's Titan has thick Nitrogen atmosphere, liquid ethane/methane oceans
-Other Saturn moons show signs of geological activity

Describe how tidal forces affect geological activity on jovian moons

-Tidal forces can cause volcanoes due to tidal heating when closer to its planet in orbit
-Prevents large moons from accreting close to the planet, forming rings from balls of ice blasted off of small moons attempting to form

Discuss why scientists no longer consider Pluto a major planet.

It does not dominate its orbit since Neptune crosses through it

Describe the evidence indicating that a major impact killed the dinosaurs.

-No dinosaur fossils above a certain level of rock
-Iridium layer from Meteorite below rock with no fossils
-Fossils all found below iridium layer

Assess the probability that a major impact will cause widespread devastation or mass extinction within the next century.

-1/1 million chance for a mass extinction
-1/1,000 chance for a widespread devastation

Describe how extrasolar planets have been indirectly detected through observations of the host stars.

-We look for periodic wobbles of the host stars to indirectly detect planets causing them based on their distance
-Use Doppler Shifts of the host star's spectrum to determine the velocity range of the wobbles and its orbital period
-Velocity range of wobble shows planet's mass
-Period shows radius of planet's orbit
-Can also detect if they eclipse the star and determine size from shadow of eclipse

Estimate the orbital distance of an extrasolar planet from its orbital period.

The shorter the period (wavelength), the closer the orbital distance is

Distinguish between comets, asteroids, and meteorites.

-Comets: Balls of ice from the Kuiper Belt/Oort Cloud that have tails as the ice melts
-Asteroids: Chunks of rock leftover from planetesimals not forming between Mars and Jupiter
-Meteorites: Rock from space that reaches Earth's surface
**Meteoroid: rock in atmosphere
**Meteor: Bright tail of debris on rock

Describe how a comet's tail changes with time as a comet orbits the Sun.

-It forms as sunlight melts the ice, releasing gas and dust as it gets closer to it
-Tail always points away from Sun once it forms about 1 AU from Sun

Explain how meteor showers are related to comets.

It is when we pass through dust trails left by comets

Compare the properties of Pluto with those of comets and other Kuiper-belt objects.

-Icy composition like Jovian Planets and comets
-Similar in size to its moon Charon

Explain why direct detection of extrasolar planets is difficult.

The light of the planets is overwhelmed by the light from their star.

Discuss of the characteristics of extrasolar planets have led to revisions of the nebular theory.

-Massive planets that are very close to their stars are not included in original nebular theory
-Revisions decided that large planets can migrate after forming because of gravitational interactions with the disk

Assess whether hypothetical extrasolar planetary systems would be challenging for the nebular theory to explain.

They would be difficult to explain if it had a "hot Jupiter" or massive planets close to the Sun, or orbiting in different directions

Identify the two forms of balance that now keep the Sun stable.

-Gravitational equilibrium (There is a balance within the Sun between the outward push of pressure and the inward pull of gravity)
-Energy balance (The flow of energy from the surface matches the amount released in the core)

Predict how the Sun's core would respond to a change in temperature.

If it shrank it would heat up significantly, then expand and cool down again

Describe the evidence that supports our understanding of the Sun's interior

-Patterns of vibrations on the surface correlate with models of the interior core temperatures
-Mathematical models use the observed composition and mass of the Sun along with the laws of physics to derive equations that describe the gravitational equilibrium, solar thermostat, and rate at which energy moves from the core to the photosphere.

Describe how solar activity affects humans.

-Charged particles from the Sun can disrupt electrical power grids and satellites
-Particles high in our atmosphere cause auroras (northern lights)

Determine the change in apparent brightness that would result from changing the distance to an object of constant luminosity.

The more distant it is, the dimmer it appears
**inverse square law of luminosity

Estimate the surface temperature of a star from its color.

More blue = hotter
More red = cooler

Identify the information needed to measure the mass of a star.

-Orbital period and average distance of an object nearby then use Kepler's 3rd law
-If not orbited by anything determine if it is main-sequence and its spectral type

Explain why neither chemical nor potential energy can account for the Sun's power output.

The Sun outputs solar radiation (electromagnetic spectrum) and thermal energy

Identify nuclear fusion as the source of the Sun's power.

-Hydrogen fusing together into helium
-Will exhaust its fuel in about 5 billion years

Arrange the layers of the Sun in order of distance from the center.

Core, radiation zone, convection zone, photosphere, chromosphere, corona

Explain why high temperatures are needed for nuclear fusion.

High temperature causes nuclei to move at faster speeds, creating the force to bind them together when they collide

Identify the output products of nuclear fusion of hydrogen in the Sun.

Helium, gamma rays, positrons, and neutrinos

Describe how the energy released by fusion travels to the Sun's surface.

It leaks out of the radiation zone as bouncing photons, rises or falls based off of temperature of gas (hot rises), then escapes through the photosphere

Identify magnetic fields as the main driver of solar activity.

-Sunspots are colder than other parts of surface and have strong magnetic fields
-Magnetic fields suppress convection and stop plasma from going into the sunspot

Describe how solar activity changes with time.

Number of sunspots rises and falls over 11-year cycle due to winding and magnetic field movement

Explain the difference between luminosity and apparent brightness.

-Luminosity:Amount of power a star
radiates (energy per second)
-Apparent brightness:Amount of starlight that reaches Earth (energy per second per square meter)

Determine the change in parallax angle that would result from changing the distance to a nearby star.

The farther away the star is, the smaller the parallax angle gets

Identify the information needed to determine the luminosity of a star.

-Distance and apparent brightness
-Luminosity = 4π(Distance)^2(Brightness)

Explain how one can measure the temperature of a star from its spectrum.

-Use the spectral type OBAFGKM (hot to cold) and color of the star
-Hotter objects emit more light at all wavelengths
-Hotter objects tend to emit light at shorter wavelengths and higher frequencies

Arrange the spectral types of stars in order of decreasing temperature.

OBAFGKM
-also decrease in luminosity and mass
-increase in lifetime

Explain why stellar mass measurements are particularly accurate in eclipsing binary systems.

Two stars orbit each other in this system and the eclipse can tell us when we are viewing it edge-on, so you can then use Kepler's third law

Interpret the characteristics of stars plotted on an H-R diagram.

Surface temperature, luminosity, and solar radii

Identify on an H-R diagram the regions corresponding to the main sequence, giants, supergiants, and white dwarfs.

-Main sequence: diagonal line through middle, majority of stars SUN included in type G main sequence
-Giants: middle right below Supergiants, yellow/orange
-Supergiants: top right, redder stars, high luminosity & low surface temp
-White Dwarfs: diagonal in bottom left, white/blue, remains of a star that ran out of fuel for nuclear fusion

Estimate the lifetime of a star from its mass and luminosity.

-Mass gives a measure of the amount of "fuel", luminosity gives a measure of the rate at which this "fuel" is consumed by nuclear burning
-Massive stars use their nuclear fuel at a much greater rate than less massive stars.

Arrange star clusters in order of increasing age based on H-R diagrams of their stars.

-Low-mass star clusters are older because large-mass stars already died off
- More blue/white/yellow is younger
-More red/orange is older
- the closer to bottom right the cluster is, the older it is

Construct an H-R diagram from a data set listing the luminosities and surface temperatures, spectral types, or colors of stars.

-Luminosity increase on y-axis
-Surface temperature decrease on x-axis
-Spectral type/color decrease along x-axis (blue to red)

Estimate the mass of a star from its location in an H-R diagram.

We can only estimate mass of main-sequence star, which decreases from upper left to lower right on the diagonal

Compare the relationships in size among giants, supergiants, white dwarfs, and the Sun using scale models

White dwarfs (smallest), then main sequence, then giants, then supergiants

Distinguish between the two basic types of star clusters.

-Open clusters are found in the disk of the galaxy, A few thousand loosely packed stars
-Globular clusters are up to a million or more stars in a densely packed ball, all remaining stars are very old.

Prove the age of Earth and our solar system is known to be
between 4.5 and 4.6 billion years *written response*

- We can measure decaying of elements in meteorites by using the concept of half-life to determine the age of them(for example the half-life of potassium into argon is 1.25 billion years and the amount of argon we have proves it to be 4.6 billion years since it was potassium)
-we observe the amounts of the isotopes that develop using the models of radioactive decay and that determines the age of the meteorite

Prove Nuclear fusion of hydrogen into helium has enabled the Sun to shine for billions of years *written response*

-observing neutrinos released from the Sun's core, we directly compare it to computer models.
-we use the model E=mc^2 to explain fusión going on

Prove Giant meteorite impacts have had devastating
consequences for life in the past and will happen again in
the future *written response*

-Dinosaurs went extinct suddenly from an impact and we know this because their fossils are found in a specific layer of rock along wit iridium, and iridium is found alone in the layer above them
- it will happen in the future based on studying cratering on earth and dating those extinction-level impacts to about 100 million years
-the nebular theory explains that there is still debris in the solar system that has potential to strike Earth

Prove Planets like Earth are numerous in our galaxy *written response*

- the Nebular theory explains the likely formation of other solar systems which would have planets forming under similar conditions
- use the transit method to detect extrasolar planets and their size, then measure several transits to get its orbital period, and use Kepler's third law to figure out its distance from the star

Prove Earth's climate is changing because of human activity. *written response*

-Carbon dioxide in the atmosphere is increasing as well as average global temperature
-Average surface temperature, growing seasons, and movement north is increasing consistent with an increase in burning of fossil fuels and deforestation
-carbon dioxide gets trapped because of the greenhouse effect, so as more CO2 is emitted, the more our climate is affected by the increasing greenhouse effect
-use climate model that shows temperatures increasing