Astronomy Term Two Test Learning Outcomes Flashcards
studying for term two test (celebration of intelect
name the terrestrial planets
mercury, venus, earth, mars, (moon)
name the existing moons of each terrestrial planet
mercury ; none
venus ; none
earth ; one (THE moon)
mars ; two (phobos and deimos)
what are the steps in terrestrial planet formation
first; the planet forms and energy turns into thermal energy in the planet’s interior.
second; differentiation converted additional energy as the denser materials sank to the core
third; radioactive materials decay and release heat into planetary interiors
what are the 3 layers of all terrestrial worlds interiors?
Core, Mantle, Crust
What is the density of the core?
the core is always made of the highest density materials such as metals (remember that this was the densest material as it sunk to the CORE during differentiation)
What is the density of the mantle?
The density of the mantle is moderate, as this is the material with high enough densities to sink past the crust but not dense enough to exist within the core.
What is the density of the Crust?
this is the lowest density, makes up our earths skin.
2 geological features of earth
All 4 geological processes exist on earth
Earth is unique for our tectonic plate processes
2 geological features of the moon
the moon is geologically dead
has few tectonic features but no evidence for recent geological activity
2 geological features of mars
evidence for all 4 geological processes but no active volcanism or tectonics
has present water but only in the form of water ice
2 geological features of mercury
considered geologically dead
few tectonic features bot no evidence for recent geological activity
2 geological features of venus
active volcano
impact craters (far less than the moon, mercury and mars tho)
4 surface shaping features of the terrestrial worlds
- Tectonics
- Impact Craters
- Volcanism
- Erosion
Role of internal heating in terrestrial planets surface features
Internal heating is required for volcanic and tectonics
What makes up earths atmosphere?
Nitrogen, Oxygen, Small amounts of other gases
What makes up Mercury’s atmosphere?
Helium, Sodium and Oxygen
What makes up Mars’ atmosphere?
Carbon Dioxide, Nitrogen, Argon
What makes up Venus’ atmosphere?
Carbon Dioxide, Nitrogen
What is the Greenhouse Effect?
The greenhouse effect is what prevents our planet from freezing. It is the process of greenhouse gasses in an atmosphere warming the planets surface.
What is the Runaway Greenhouse Effect (aka) Positive Feedback Loop
The concept in which evaporation (& greater capacity for water-vapor) causes more water-vapor, causing more greenhouse gasses, causing planetary temperatures to rise, causing more evaporation, more water-vapor, more greenhouse gas, higher planetary temperatures (and a continuous loop until the planet inevitably becomes geologically dead)
What are the causes of climate change?
Human activity causes excess greenhouse gasses.
Difference between the greenhouse effect and the ozone hole
the greenhouse effect is a natural process that allows planetary surfaces to warm due to trapped gasses.
The ozone hole is in place due to human behavior driving excess greenhouse gasses causing temperature to rise in our atmosphere and damaging it.
Name the Jovian Planets
Jupiter Saturn Uranus Neptune
Jovian Planet Formation
Jovian planets formed in the cold reaches of the solar system, far from the sun. Due to this their cold temperature allowed the hydrogen compounds to turn into ice, and grow large enough to create a gravitational pull to draw in hydrogen and helium surrounding them and grow larger.
Jovian vs Terrestrial Planet Formation
Jovian planets draw in hydrogen and helium from their surroundings and grow. Terrestrial planets formed in regions that were hot enough to allow the process of differentiation.
Name the 6 Jovian Moons
Io, Europa, Ganymede, Calisto, Titan, Enceladus
Which Planets Home the Jovian Moons?
Jupiter ; Io, Europa, Ganymede, Calisto
Saturn ; Titan, Enceladus
Why do the Jovian Planets appear as different colors?
different chemical compounds allow the Jovian planets to appear as different colors.
methane causes Uranus and Neptune’s cloud to appear as blue.
What is the expected lifetime of Jovian ring systems?
Larger particles in the Jovian rings are constantly being ground down by impacts of surrounding particles. New particles are constantly being supplied, to replace those that are destroyed. Ring particles cannot last for billion years, so the rings we see today are compiled of recent particles.
What is the composition and location of Asteroids
COMPOSITION
Majority of asteroid’s (75%) are Carbonaceous. There are also Silicate Asteroids which are rocky (17%) and Metal Rich Asteroids (8%)
LOCATION
The vast majority of Asteroids orbit the sun in the asteroid belt between Mars and Jupiter. Jupiter’s gravity shapes their orbits and prevents asteroids from accreting into a planet.
What is the composition and location of Comets
COMPISITION
Composed of ice and rocky dust. Ice begins to vaporize and escape as comet ascends towards the sun, creating the comets tails (Plasma and Dust Tails)
LOCATION
Many comets come from the Oort Cloud or Kuiper Belt.
What is the composition and location of Kuiper Belt Objects
COMPOSITION
The Kuiper Belt is comprised of icy objects. Many objects in the belt should have similar compositions to Pluto as they formed in the same region.
LOCATION
Objects in the Kuiper Belt reside in the Kuiper belt, located far beyond the orbit of Neptune.
What is the composition and location of Dwarf Planets
COMPOSITION
dwarf planets are objects that are not large enough to be considered a planet, but large enough to be spherical.
LOCATION
There are 5 recognized Dwarf planets. Ceres lies in the main asteroid belt (between Mars and Jupiter) where the rest reside in the Kuiper Belt.
Where does the Main Asteroid Belt reside?
Between Mars & Jupiter
How do Small Bodies differ from our 8 Planets in our Solar System?
small bodies are too small to be considered planets.
What is the Gravitational Influence of the planets on small bodies?
Impacts are always in some way related to the gravitational impacts of the Jovian planets. These influences have shaped the Kuiper belt, the Oort cloud, and determine when an object is flung where.
Why should Pluto be considered a Kuiper Belt Object?
Pluto is smaller and icier and more distant than all planets. Scientists believe that all objects in the Kuiper belt have similar compositions to Pluto.
What is the Asteroid Impact on Earth?
an impact could cause widespread physical impact. Asteroid impact caused extinction of 99% of all living organisms to die. Smaller impacts occur every couple hundred years.
What are 2 famous impacts from asteroids?
Tunguska Siberia & Chelyabinsk Russia
What is a Meteor?
a flash of light caused by a particle of dust or rock entering our atmosphere at high speed (shooting or falling stars)
What is a Meteoroid ?
a small to boulder sized particle of debris in the solar system
What is a Meteorite?
a rock large enough to enter the atmosphere, survive and reach the ground
What are the 2 ways to discover Exoplanets
- Direct Imaging
- Indirect Imaging
What is Radial Velocity?
radial velocity (doppler shift) method measures changes in the stars velocity, detecting through the motion of a star.
What is Transit Photometry?
relies on searching for slight changes in a stars brightness. searches for transits and eclipses by carefully monitoring a star over time.
What is selection effects?
selection effects are the biases or limitations in detection of exoplanets based on transit and radial methods.
results in selection effects (properties of the planet found are NOT representative of all the planets, but biased due to the limitations of methods)
What is the timescale for the discovery of exoplanets?
the nebular solar theory was established decades ago however it took many decades of technology to be able to test this prediction.
What are the established properties of exoplanets?
similar to those in our solar system. gas giants, ice giants, terrestrial and super earths (mix of rocky and gas shrouded exoplanets larger than earth). these planets can orbit a star or nothing at all.
What is Keppler missions rationale?
Kepler’s mission detected so many planets that scientists can use statistics to estimate the proportion of all stars that have planets.
What is Keppler missions results?
Concluded that at least 70% of all stars harbor 1+ planet. Many of these planets are quite small proving earth sized planets are quite common.
What are the properties of the Sun?
primarily made of hydrogen and helium. mass is 300 thousand times more than earth.
Why is the sun not powered by chemical or gravitational energy?
the sun converts mass into energy through nuclear fusion.
What is the Sun’s photosphere?
the photosphere is what we see. it is not a solid surface and has low enough density so that more photons are emitted.
What is the suns convective zone?
in the convective zone energy moves through convection. temperature is 2 million and plasma can absorb more photons here.
What causes granulation on the Sun?
convection in the photosphere causes granulation as it is the visible surface of the sun so appears granulated due to cells called granules (caused by convective currents)
What is the Sun’s chromosphere?
it is a thin and pinkish layer seen during total solar eclipse. Emits UV.
What is the Sun’s Corona?
low density, millions of degrees and can be observed in UV, C ray and visible light
What is the Solar Wind?
Charged particles (plasma tails of comets)
What is the sun’s cycle of activity?
The sunspot cycle is an 11-year cycle that can be measured by any sunspot and location. Solar max is lots of activity and solar min is very little activity.
What are the suns magnetic fields and sunspot?
The sun’s magnetic fields prevent hotter plasma from entering regions. Spectral lines show presence of fields.
What is the suns prominence?
Prominence is the large bright gas features extending outward from the sun’s limb. Some of these break apart.
What are the sun’s filaments?
These are the large regions of cool gas on the sun’s surface. They appear as dark and are similar to prominences.
What are Solar Flares?
they can produce prominences and filaments and result in bursts of x-rays and fast-moving charges.
What are Coronal Mass Ejections?
bubbles of highly energetic charged particles sent out from a solar flare
What is the role of magnetic fields in the sunspot cycle?
prevents surrounding plasma from entering the sunspot, so the sunspots stay cooler. they stay until the magnetic field gets too weak to hold the plasma off.
What is the Hydrostatic (aka) Gravitational Equilibrium?
The hydrostatic equilibrium is a state of balance in which the force of gravity pulling inward is counteracted by pressure pushing outwards. The outward push comes from internal gas pressure and the inward pull is caused as each layer of the sun is greater while working deeper into the sun. This causes pressure to increase with depth.
What is the difference between fusion and fission?
Fusion is the process in which one or more nuclei fuse together into one. Fusion is the process in which the sun gains its energy.
Fission is quite the opposite, being the process of one nucleus splitting into multiple. This is how many forms of energy are created on earth.
What does E = MC2 have to do with the Sun and Stars?
This calculation tells us that mass contains an enormous amount of potential energy. It allowed us to learn that the sun converts mass into energy through the process of nuclear fusion.
What is the Solar Neutrino Problem?
Solar neutrinos are particles that come directly from the Sun’s core and travel to Earth’s surface within minutes. Solar neutrinos are special particles that can pass through virtually anything. The problem is that in principle, neutrinos would be a great tool in studying the Sun’s core, however, as they can pass through almost anything it is very challenging to stop a neutrino to be able to study it.
What is the solution to the Solar Neutrino Problem?
The solution to study solar neutrinos is very strong detectors, that are normally placed deep underground under Antarctic ice. The ice blocks most other particles but neutrinos pass through and are able to be detected and studied.
What is the range in Stellar mass, luminosity and temperature compared to the Sun?
They range from a 10th of the sun’s math to 200x the sun’s mass and live for millions to billions of years.
How are Stellar distances measured?
the distance is calculated using inverse square law, but the most direct way to find the distance is by using stellar parallax.
What is difference between luminosity and apparent brightness?
luminosity is the light emitted from the surface and apparent brightness is what we see from earth
What information is needed to determine a stars luminosity?
The temperature of the radius and apparent brightness.
How can you tell the surface temperature of a star from its color?
A red star is cooler than a blue star. The hottest stars shine blue-white while the coolest star is dull orange or red.
What is the spectral classification
OBAFGKM (Oh, Be, A, Fine, Girl, Kiss, Me!)
Each type is numbered into sub categories (b1, b2 etc)
The larger the number, the cooler the star
Because the older you get the cooler you get and taya is the oldest and the coolest so
What information can be obtained from binary stars?
Information about stellar masses, evolution and gravitational interactions
What information can be obtained from star clusters?
information about stellar populations, distributions, and serve as distance indicators.
What is plotted in a Hertzsprung Russel Diagram
the stellar surface temperature and the stellar luminosity
How is a Hertzsprung Russel Diagram used?
the horizontal axis represents stellar solar temperature, decreasing from left to right as the diagram is based on OBAFGKM
the vertical axis represents stellar luminosity, each tik mark represents a luminosity 10x larger than the prior.
What is interstellar medium?
The matter and radiation that exist in the space between the star systems.
What is Interstellar Medium made of?
mostly hydrogen and helium as well as very little dust.
How does star formation occur?
gravity causes a cloud of interstellar gas to contract until the central objct becomes hot enough to sustain nuclear fusion in its core.
How long does star formation typically take?
can take up to 10 million years but depends on a star’s mass.
Why is star formation difficult to study?
gas and dust absorb much of the visible light produced by the stars.
What are the observational signatures of star formation?
confirms the idea that stars are born within the coldest and densest clouds as they are cold enough to allow atoms to combine.
Where are stars born?
in the coldest and densest clouds, cold and dense enough to allow atoms to combine
What is the role of disks and angular momentum in star formation?
protostars are not yet stars as their cores are not hot enough for nuclear fusion. winds and jets help clear away excess gas surrounding a forming star, revealing the protostar. Also allows protostar to shed some angular momentum by carrying material off into space and causing the rotation to slow down.
What is a brown dwarf?
A failed star that is too small to become a star, and cannot complete nuclear fusion.
How does mass and luminosity determine a stars lifetime?
if it massive and brighter (higher luminosity) its life time is shorter
What is shell burning and when does it occur?
When nuclear fusion reaction occurs in a shell surrounding a star core. Typically occurs in intermediate and high-mass stars during certain phases of evolution.
Why do stars leave the main sequence?
When they run out of hydrogen fuel in their cores, leading to their evolution into different phases of stellar life.
What are the different post-main sequence changes in stars of different mass?
low - intermediate stars (the sun) expand into red giants and eventually shed outer layers to form planetary nebulae, leaving behind a white dwarf
high mass stars (several x the mass of the sun) expand into super giants and form heavier elements in their core. can end their lives in supernova explosions leaving behind black holes.
What are the stages in stars lives?
Main Sequence Phase
Red Giant Phase
Supergiant Phase
Supernova Phase (if applicable)
Remnant Stage
What are the timescales for the stages of the stars?
Main Sequence Phase
10 billion years (low/int mass) / few million years (high mass)
Red Giant Phase
few hundred million years (low/int mass) few million to few hundred thousand (high mass)
Supergiant Phase
few hundred thousand to a few million (high mass)
Supernova Phase (if applicable)
a few days to a few weeks
Remnant Stage
indefinite, or trillions of years
Why cant elements heavier than Iron produce energy through fusion?
Fusion processes involving these elements require an input of energy, rather than releasing energy.
How do massive stars give rise to supernovae?
they end their lives in supernovae through core collapse, as their iro core collapses over its own gravity and makes a shockwave that triggers a powerful explosion leaving a dense rememnant like a neutron star or black whole
What does “We are made of Stardust” mean?
suggests that our bodies originated from nuclear fusion processes inside stars
How does mass transfers in binary systems alter the stars histories?
Mass transfer can change a stars masses, evolutionary paths and end states.
What is a white dwarf?
the core of a star that has died
What is a neutron star?
The ball of neutrons created by the collapse of the iron core
What is a black hole?
a place where gravity is so strong that nothing can escape
What is degeneracy pressure?
Like a crowded room where particles like electrons or neutrons cannot ocupy the same place
How do intermediate mass stars end?
Neutron stars or black holes
How do low mass stars end?
White Dwarfs
How do high mass stars end?
Neutron stars or black holes
How do very high mass stars end?
May end in a super nova
What is a white dwarf supernova
when a white dward accuplated too much mass from its companion leading to a runaway nuclear fusion reaction
Why are white dwarf supernovas important?
Because they serve as standard candles for measuring cosmic distance, and provide insights into stellar evolution
What are some misconceptions about black holes?
Black holes “suck” everything : their gravitational pull ONLy effects objects very close to them
Black holes are “gates” : no evidence that they lead to other universes
Black holes swallow everything : they do not consume, their gravitational effects will eventually cause objects to evaporate.
Why are pulsars considered neutron stars
Because the exhibit regular and rapid pulses of radiation
