[MID TERM] Lesson 4: Solar System, Nebular Theory, Age of Solar System, Earth, Mercury and the Moon, Venus, Mars Flashcards
Describe the basic regions of the solar system.
Inner solar system, Asteriod belt, Outer solar system, Kuiper belt
Be able to provide a basic solar system census: how many known objects of each category are there in the solar system?
- 1 mid-sized main-sequence star
- 8 planets
- 5 Dwarf Planets (aka Pluto like planets)
- 200+ moons (1 Earth, 2 Mars, 92 Jupiter, 82 Saturn, 27 Uranus, 14 Neptune, 5 Pluto)
- 1,000,000+ asteroids
- 3701+ comets
What are Rocky Planets? What are Gas Giant Planets?
Rocky: Mercury, Venus, Earth, Mars
Gas: Sun, Jupiter, Saturn, Uranus, and Neptune
what are the basic properties of the asteroid belt
- located between Juipter and Mars
- consists of 1,000,000 irregularly shaped objects (much smaller than planets)
- objects called asteriods, minor planets, or dwarf planets
Cluster due to Juipter’s and the Sun’s gravitational pull
* gravity bonds these objects together as each of them don’t have a gravitational pull
describe some of the moons in the outer solar system, and why they are so unique
Jupiter’s Moons
* Io: the most volcanically active object in the solar system
* Europa: Possible subsurface ocean - more water than Earth
* Ganymede: Largest moon in solar system
* Callisto: A large, cratered “ice ball”
Saturn’s Moon
* Titan, Saturn’s largest moon - only moon with a dense atmosphere (thicker than the Earth’s)
Neptune’s Moon
* Triton: a retrograde moon, possibly from collision or captured
what are the basic properties of the Kuiper belt
a circular band of objects that exists beyond Neptune’s orbit
* the largest object is Pluto
* Belt of comets (primarly ice objects)
What is an astronomical unit?
Use astronomical units (AU) - scale from Earth to the Sun
* Earth to the Sun = 1 AU
What is the IAU definition of a planet? Be able to explain in detail why Pluto is not considered a planet.
list the three requirements
- must orbit a star (this excludes moon)
- must be spherical (this excludes most asteroids, comets, etc.)
- must have cleared the debris in its orbit (excludes all asteroids and KBOs, including Pluto!)
Not involved with any belts
What is a dwarf planet?
Dwarf Planet: star-orbiting spheres that didn’t clear out their orbits. e.g. Pluto, Ceres, Haumea, Makemake
What is the Oort cloud? Have we ever observed an object from the Oort Cloud? How do we know its there?
**Oort Cloud ** : comets that are confined to the plane but come from all directions
* Hale-Bopp is a famous comet that has been beyond the Kuiper Belt and orbits all around the Oort cloud to eventually orbit back to the solar system after years
What are some of the properties of the solar system that point towards how it as formed?
5 points
- mass distribution - how most of the mass (material) is in the Sun and the the rest of Juipter, Saturn and everything else
- the motion of planets - most planets are prograde (spin counter-clockwise) and a few retrograde (spin clockwise aka Venus)
- Orbits are roughly circular
- Two major planet types - Terrestrial and Jovian
- Cratering
What is the Nebular Theory?
According to the nebular theory, our solar system formed from giant cloud of interstellar gas
* (nebula = cloud)
How does the Nebular Theory explain the properties of the solar system (same properties discussed)? What are some exceptions to the theory? How do we explain those exceptions?
mass distribution - most of the matter is complied in the Sun and the leftovers went to mainly Juipter and Saturn and the rest
the motion of planets - due to collisions during the beginning that twisted the planet’s axis
Orbits are roughly circular - caused by the conflicting pull of gravity from the Sun and other planets
**Two major planet types **- Terrestrial and Jovian - beacause of the frost line…
* Inside the frost line: too hot for hydrogen compounds to form ices
* outside the frost line: cold enough for ices to form
Then, inside the line planetesimals of rock and metal build up as these particles collide.
Next, outside the line, planetesimals of gases such as hydrogen and hellium were formed
Cratering - Leftover planetesimals bombarded other objects in the late stages of the solar system formation
Heavy Bombardment era - when most of the craters formed during the early stages of the solar system
What is the conservation of energy? How does the Conservation of Angular Momentum relate to the Nebula theory
what did the Conservation of Energy do for the solar system
Conservation of Angular Momentum: The rotation speed of the nebula must have increased as the cloud contracted more material in
* ex. Ice Skater spins faster when they put their hands together
Conservation of Energy: As gravity causes the cloud to contract, *it heats up *
* Helped the inner parts of the disk are hotter than the outer parts, rock can be solid at much higher temperatures than ice.
How does a roughly spherical cloud become a flattened disk?
Hint: particles
Collisions between particles in the cloud caused it to flatten into a disk
What role did the solar wind have in the forming solar system?
Radiation and outflowing matter from the Sun — the solar wind — blew away the leftover gases
Provide evidence from beyond our solar system that the Nebular Theory of solar system formation is correct.
where did Earth’s water come from? Where did the Moon come from?
Earth’s water - Water may have come to Earth by way of icy planetesimals from the outer solar system; from Heavy Bombardment era
Moon - Giant Impact Hypothesis - A Mars-sized planetesimal crashed into young Earth; the leftover debris became the moon; from Heavy Bombardment era; caused Earth’s tilt
How do we measure the age of the solar system?
ROCKS!! We can determine the age of a rock through careful analysis of the proportions of various atoms and isotopes within it
What is radiometric dating? How does it work?
Radiometric dating relies on careful measurement of the proportions of various atoms and isotopes inside the rock
* We can crack open the rocks, and use the elements inside to figure out how long they date back
What is radioactive decay?
an unstable atomic nucleus loses energy by radiation
What does the term ‘halflife’ mean?
Half life: the time it takes for about half of the sample to decay from the original (parent isotope) into a new type of atom (daughter isotope)
How old is the solar system?
4.6 billion years old
* from the oldest metorite Argon
What are the basic layers of Earth? What are they made of?
Core: highest density; nickel and iron (made of metal)
Mantle: moderate density; minerals with silicon, oxygen, etc. (made of rock which is a bunch of oxygen bonded with silicon)
Crust: lowest density; granite, basalt, etc.
What is differentiation?
Differentiation: the process planetary material separating by density
* Lower density material rises to surface
* Higher density material sinks to centre
What drives geological activity?
Ex. tectonic plates, volcanoes, earthquakes
Heat
How long does it take for a convection cycle in the mantle to occur?
define convection in terms of Mantle and how long
Mantle convection: hot rock rises and cooler rock falls
* One convection cycle takes 100 million years on Earth
What are the main sources of internal heat of the Earth?
3 Sources
- Gravitational potential energy of accreting planetesimals - from when earth was formed
- Differentiation
- Radioactivity - atom expels energy from the nucleus in the form of a particle or ray
What is the most dominant source of internal heat today?
Radioactivity in the Earth’s Mantle
How does a planet cool off? What are the physical methods by which heat is transported out of Earth’s interior into space?
- Convection: transports heat as hot material rises and cool material falls
- Conduction: transfers heat from hot material to cool material
- Radiation: sends energy into space
Convention takes a hot rock to the surface - so transporting heat to surface through rock
To get heat through the crust is done by conduction - the transfer of heat through touching, a hot rock touching a cool rock will warm up cool rock
Finally, the heat is transferred into space
What role does size play in the length of time it takes for it to cool off?
Smaller worlds cool off faster and harden earlier
* The Moon and Mercury are now geologically ‘dead’
How is the Earth’s magnetic field generated? How does it create the aurora
Moving charged particles create magnetic fields
* A planet’s interior can create magnetic fields if its core is electrically conducting, convecting, and rotating
This magnetic field is generated by moving material in Earth’s liquid metallic core.
In the ionosphere, the ions of the solar wind collide with atoms of oxygen and nitrogen from Earth’s atmosphere. The energy released during these collisions causes a colorful glowing halo around the poles
* aurora is the northern lights
How do we use earthquakes to measure the layers of the Earth?
define difference between P-waves - P for push and S-waves - S for side
P-waves push matter back and forth
S-waves shake matter side to side
* both are earthquakes
P-waves go through Earth’s core, but S waves do not
* We conclude that Earth’s core must have a liquid outer layer
What are some geological processes that act to resurface a terrestrial planet? Explain how each work.
4 key processes
Impact Cratering
○ Impacts by asteroids or comets
Volcanism
○ Eruption of molten rock onto surface
Tectonics
○ Disruption of a planet’s surface by internal stresses
Erosion
○ Surface changed made by wind, water, or ice
What role does our atmosphere play on Earth? Also, why is the sky blue?
4 roles including blue atmosphere
- Erosion - weather
- Radiation protection
- Greenhouse effect -regulates our temperature, holds onto heat of infrared photons (hydrogen, Carbon dioxide, Methane)
- Makes the sky blue!
* Atmosphere scatters blue light from the Sun, making it appear to come from different directions
What signs do we have that the the Moon was volcanically active in the past?
define lunar maria
Some volcanic activity 3 billion years ago must have flooded lunar craters, creating **lunar maria **
* The maria is the dark spots on the Moon
What are the internal layers of the Moon? How are they the same/different from the Earth?
The moon is differentiated
○ It has a liquid core
The crust is thinner on the Earth- facing side
The core is iron and nickel but is smaller than Earth’s
What is the difference between the nearside/farside of the Moon?(Bothinternally and externally)
The far side of the moon looks very different, very few maria and many more craters
* less volcanic activity on the other side
What’s the difference between the Moon’s sidereal month and synodic month? Why?
Moon’s** sidereal month**—time for the Moon to orbit 360° around the Earth relative to the “fixed” stars—is a little over 27 days
* measures complete Moon orbit
Moon’s synodic month — a month of approximately 29.53 days, measured from a lunar phase until the return of that same phase
* measures complete Moon phase cycle
What does synchronous rotation mean? What, exactly, is synchronized in the Moon’s orbit?
We always see the same side of the moon
* because Moon’s rotation period and orbital period are equal
* Sideral month = synodic month
What are ‘scarps’ on Mercury? How were they formed?
Scarps - really long cliffs
* The cooling off a planet has caused the planet to shrink, creating long cliffs in the process
Describe recently geologic activity on Mercury. Where was water found on Mercury? Why is it still there?
‘hollows formed as easily vaporized minerals escape’
Water:
Mercury’s axial tilt is 0°, as a result there are permanently shadowed craters at the poles.
* Water is in these super low creators (shadow regions) so that sunlight can’t get to it
What are the internal layers of Mercury? How are they the same/different from the Earth/Moon?
Mercury has some similar layers to Earth, but in different proportions, it has a very large core compared to Earth’s
Briefly describe Mercury’s orbit, and how it affects a solar day.
Orbital resonance: Mercury’s orbit is 88 Earth- days long, and in 59 days it’s completes one full rotation on its axis
* As a result: a ‘solar’ day on Mercury is 176 days
→ Because its spins is so slow, it takes a whole orbit to get from midnight to noon
Describe Venus’ atmosphere
define runaway greenhouse effect
- Venus has a very thick carbon dioxide atmosphere with a surface pressure 90x that of Earth
The extremely high level of carbon dioxide has lead to the runaway greenhouse effect that has caused the extreme surface conditions.
→ High carbon dioxide levels in the Venusian atmosphere may have trapped enough heat to have boiled away the oceans.
- Most of our carbon is locked inside rocks - The rocks hold more CO2 then water, if rocks were heated by the sun, the CO2 goes into the atmosphere….
Describe some of Venus’ surface features
- catering
- volcanoes
- There are two major highland regions Ishtar Terra in the North and Aphrodite Terra nearer the Equator of Venus
- Mountains
Why does Venus have very few craters?
The thick atmosphere keeps material thrown aloft by meteorite impacts from traveling far
Does Venus have active plate tectonics like Earth?
Fractured and contorted surface indicates some tectonic stresses
What is unique about Venus’ spin?How do we explain this in context of the Nebular Theory?
Axial tilt 177 degrees
Venus rotates on its axis retrograde
* This rotation is very unusual, and may result from some sort of extreme collision or other event in Venus’ past.
Does Venus have a magneticfield? Why or why not?
Venus’s slow rotation may also be the cause of a lack of detectable planetary magnetic field.
Phosphine on Venus. Have we found evidence of life in the Venusian atmosphere?
big hint: LIFE
Evidence indicates phosphine, a gas associated with living organisms, is present in the habitable region of Venus’ atmosphere
How long is a Martian Day (aka, a ‘sol’)?
24 hours and 37 minutes
What about a Martian Year?
Every year on Mars is equivalent to two years on Earth
What is Mars’ axial tilt? How has it changed through time?
25 degree tilt
* tilt of Mars have been changing for hundreds of thousands to millions of years
Describe some various characteristics of Mars: atmospheric composition? Some geological features?
- Has a composition consisting primarily of silicates but with a small metal core
- has no global magnetic field
- has no liquid material in its core today that would conduct electricity
- the surface of Mars has continental or highland areas as well as widespread volcanic plains.
About half the planet consists of heavily cratered highland terrain
Roughly, how many missions have been to Mars?What is the success rate?
50 spacecraft missions
* half of them have been successful
How many missions are there currently operating at Mars?
- 12 active missions
What is one contribution Canada has made to operations and discoveries at Mars?
Phoenix Lander - used robotic arm to take samples on Mars
What is MOXIE?
MOXIE will test a way for future explorers to produce oxygen from the Martian atmosphere for burning fuel and breathing
What are extremophiles? What is an extremophile called if it lives in an extremely salty (saline) environment?
Extremophiles: organisms that live/thrive in environments that make survival challenging
* Ex. Organisms that live in volcanoes
called Halophiles if they live in salty conditions
What is a ‘planetary analogue’? Why do we study them?
Areas that are similar to Mars, and other planets that can roughly be found in certain areas on Earth
* we study certain areas on Earth to explain things better about areas on other planets
What is required to calculate the density?
d = M/V
* M - Mass
* V - Volume
How does crater counting work?
One way to estimate the age of a surface is by counting the number of impact craters
* The more craters there are in the area, the older the location
What are seismic waves?
waves that spread through the interior of Earth from earthquakes or explosion sites
The crust of Earth is covered in two major types of rocks, what are they?
granite and basalt
What is a magnetosphere? where does it comes from?
Magnetosphere: Above Earth’s atmosphere, our field is able to trap small quantities of electrons and other atomic particles.
* comes from trap particles from the sun
What were the top 3 early hypotheses for the formation of the Moon?
- The fission theory—the Moon was once part of Earth, but somehow separated from it early in their history.
- The sister theory—the Moon formed together with (but independent of) Earth, as we believe many moons of the outer planets formed.
- The capture theory—the Moon formed elsewhere in the solar system and was captured by Earth.
