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the overall process of the creation of stars and planets
nebula → molecular cloud → molecular core → solar nebula → protostellar disk →protoplanetary disk → sun, planets
Interstellar medium
materials in space between stars
protostars
formed in molecular core; has protostellar disk and then this disk is called a protoplanetary disks when planets start forming
thermal energy
The energy that resides in the random motion of atoms, molecules, and particles, by which we measure their temperature; pushes outwards after cloud contacts and heats up
magnetic fields
A field that is able to exert a force on a moving electric charge. Occurs when object has molten interior and rotates at a moderately rapid speed; collapses with turbulence as collapsing cloud resists gravity
Importance of a magnetic field
Protects the Earth from harmful solar wind and cosmic radiation by deflecting charged particles away from the planet.
Nebula Theory
explains process from Nebula to Solar System formation
protostellar disk
the solar nebula settles into a protosun in the center and a disk
protoplanetary disk
forms planets (core accretion model)
exoplanets
planets orbiting around stars other than the Sun
Conservation of angular momentum
The physical law stating that the amount of angular momentum of an isolated system does not change over time; as cloud contracts, rotation increases
after conservation of angular momentum…
Collisions between particles in the cloud caused flatten into a disk (gas particles colliding reduce up & down motions)
Spinning cloud flattens as it shrinks
Grains in the disk accrete into planetesimals that eventually form into planets
Conservation of energy
The physical law stating that the amount of energy of an isolated, closed system does not change over time; Gravity causes cloud to contract and heat up
planetary systems consist of…
a star
planets/dwarf planets
moons
asteroids
comets
our solar system consists of…
Terrestrial planets
Asteroid Belt
Jovian (gas giants) planets
KBO (Kuiper Belt object)
Oort Cloud
Oort Cloud
A spherical distribution of comet nuclei stretching from beyond the Kuiper Belt to more than 50,000 astronomical units (AU) from the Sun
General characteristics of a solar system we have accepted from our Solar System
Thermal profile of a solar system and observations
Thermal profile of a solar system that is hot and cools further away from the Sun
Frost line/snow line: \n - Inside: Too hot for hydrogen compounds to form ices \n - Outside: Cold enough for ices to form
Refractory: do not melt at high temps
Volatile: melt or evaporate ate moderate temps
frost line
giants formed outside of it
terrestrials formed inside of it
Solar system observations to be explained
The large bodies orbit in same direction and plane
There are two types of planets: terrestrial and jovian (giant planets)
There are smaller bodies: asteroids and comets
Notable exceptions to usual patterns:( Most likely due to bombardment/collision) odd tilt of Uranus and Venus’ retrograde rotation
2 scenarios planet formation theories
gravitational collapse (like stars) - doesn’t explain the whole process
core accretion (the more acceptable theory)
The core of planets form by planetesimal accretion; then gas is accreted
Gas giants must form before the solar nebula dissipates (less than 10 Mys)
core accretion
Gas giant planet forms from dust and gas. Dust sticks together to form planetesimals, which grow by accreting more material. Once they reach critical mass, they attract gas and rapidly increase in size.
gravitational collapse
when the astronomical object no longer has the interior pressure to counter the gravity, so it contracts
planet formation ends when…
solar wind blew solar nebula away
A glowing, rapidly moving knot of gas and dust that is excited by bipolar outflows in very young stars.
Herbig-Haro (HH) objects
T Tauri variables
T Tauri variables are young stars that vary in brightness due to changes in their accretion rate. They have protoplanetary disks and are important for studying early star and planet formation.
asteroids
left over after accretion process; A primitive rocky or metallic body (planetesimal) that has survived planetary accretion. Also are the parent bodies of meteoroids.
comets
left over after accretion process; A complex object consisting of a small, solid, icy nucleus; an atmospheric halo; and a tail of gas and dust.
exo-planetary solar systems
not all look like our solar system
have many Jupiter sized planets really close to their star
have other planets also really close to their star
2 major detection methods
radical velocity and transmit method
radical
The speed at which an object is moving in a circular path is called __________ velocity. It is perpendicular to the tangential velocity and is dependent on the radius of the circle.
Doppler effect
The change in wavelength of sound or light that is due to the relative motion of the source toward or away from the observer.
Red shift: The shift toward longer wavelengths of light by any of several effects, including Doppler shift, gravitational redshift, or cosmological redshift.
Blue shift: The Doppler shift toward shorter wavelengths of light from an approaching object.
Wobble method
Transit Method
Method used to detect exoplanets by measuring the periodic dimming of a star's brightness as a planet passes in front of it; used by Kepler Mission
formation history
Earth formed 4.6 billion years ago from the inner solar nebula.
Interior parts of Earth
Core: Highest density; nickel and iron \n Mantle: Moderate density; silicon, oxygen, etc. \n Crust: Lowest density; granite, basalt, etc.
Interior Differentiation
Gravity pulls high-density material to center
lower-density material rises to surface \n Material ends up separated by density
Heating of Interior
early Earth: accretion & differentiation \n Current Earth : radioactive decay
Cooling of Interior (how HOT goes to COLD)
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
Geological activity that shapes the Earth’s surface
Impact cratering
from asteroids and comets
Volcanism
eruption of molten rock onto surface
Tectonics
Disruption of a planet’s surface by internal stresses
Earth is only terrestrial with plate tectonics
Erosion
Surface changes made by wind, water, ice or debris
Greenhouse Effect
Generally a good thing when occurring naturally. But when the process is sped up through human activity, it is not good
Planetary sizes
small planets cool faster than large planets → heating/cooling of interior atmosphere (to have or not to have)→ erosion (water, ice, wind, debris)
Habitual zone
the region around a star in which planets could potentially have surface temperatures at which liquid water could exist
Moon
Lowlands (Maria) à basins flooded by lava flows \n Moon formation/history (Earth was hit by Mars-sized object and ejected
material into space, eventually accreting into our Moon
Moon rock composition similar to that found on Earth
Mercury
Closest to the Sun
No tilt
Very slight ionic atmospherescarps
Caloris Basin and “Rocky Road” feature just on the opposite side of Mercury from Caloris Basin→ something big hit Mercury !!! ?
large core most likely due to massive impacts that blew away the mantle during formation
Venus
not as mountainous and not as rugged as Earth; just nasty terrain
the surface is mainly gently rolling plains;
Only Venus has: “pancakes”/Coronae craters, shield volcanoes
acid rain
extremely high atmospheric pressure (92 atm) Greenhouse Effect went into “overdrive”
Rotates cw (clockwise) → (planet knocked over upside down?)
Very slow rotator → longer rotation time than orbit time
Atmosphere rotates very quickly → once in 4 days
One hot planet: 900F everywhere
We can see phases, like the Moon
Mars
rotates just 40 mins longer than Earth
tenth of Earth’s mass
half Earth’s radius
shield volcanoes:
Olympus Mons → highest & largest in the Solar System
Tharis range
Vallis Marineris
Hellas & Argyre basins
Many features believed to be caused by water flows
Thin atmosphere mostly CO2
Has a tilt (about 25O) → has seasons
Has been explored by orbiting and roving probes, A LOT!
Life on Mars? Still searching and hoping.
Formation history for giant planets
Giants formed 4.6 billion years ago → core accretion
Gas planets
Jupiter and Saturn
Water/icy planets
Uranus and Neptune
General knowledge for Jovians (giant planets)
are made of mostly gases (H, He, H2 O, CH4 (methane), NH3 (ammonia) )
have rock/ice cores
do not have solid surfaces: gases --> liquid & solid at high pressure
have ring systems and many moons
formed faster than terrestrials (less than 3 – 5 Myrs)
large because they accumulated gas directly from the solar nebula (true for Jupiter and Saturn)
are far from the Sun
Jupiter
largest and contains ¾ of total Solar System planetary mass
Red Eye storm
core is liquid rock and water
very strong magnetic field
rotation period of 9.94 hours
magnetic field aligned with axis
Saturn
has the largest set of rings
core is liquid rock and water
is a gas planet
rotation period of 10.56
magnetic field aligned with axis
Uranus
axis of rotation is in the plane of the Solar System
98° tilt (maybe due to collision)
there’s weather change
alike to Neptune
has liquid core
rotation period of 17.23 hours
magnetic field is upside down
Neptune
crosses orbits with Pluto but will never collide
has a liquid core
is alike to Uranus
rotation period of 16.10 hours
magnetic field is off center from axis
Roche limit
distance from object where another smaller object can broken apart because of gravity
closer object gets to bigger object, the more the smaller object will stretch until it breaks
Ex.: Saturn’s rings
Note
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