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UA / Astronomy / ay 101 / What planets are terrestrial and jovian?

What planets are terrestrial and jovian?

What planets are terrestrial and jovian?


School: University of Alabama - Tuscaloosa
Department: Astronomy
Course: Intro To Astronomy
Professor: Ronald buta
Term: Spring 2017
Tags: astronomy and beginner
Cost: 50
Name: Test Two Study Guide
Description: Covers all of the material we went over in chapters 6 through 10-- I had to read through the last chapter to make sure I had all the material but its there!
Uploaded: 02/27/2017
5 Pages 70 Views 2 Unlocks

AY 101-001 Professor Buta  

What planets are terrestrial and jovian?

Test Two Study Guide (Chapters 6-10)


∙ The Solar System consists of:

o One star (the sun)

o Eight planets

o An unknown number of dwarf planets (what Pluto was demoted to)

o Over a hundred moons and satellites

o Thousands to billions of asteroids and comet nuclei  

▪ Everything in the Solar System is bound to the Sun by gravity.  

▪ The universe is thought to be about 4.7 billion years old.  

∙ Solar System hosts two kinds of planets: Terrestrial (Earth-like) and Jovian (Jupiter-like). o Terrestrial—inner solar system, rocky/metallic comp., CO2/other types of atmosphere,  small and slow

What makes the jovian planets so gassy?

o Jovian—outer solar system, gaseous with liquid surface, hydrogen/helium atmospheres,  large and fast rotating  

∙ Planetesimals—small objects that start out as tiny particles that grew over time through  condensation (rocky near the sun, icey far away from sun) If you want to learn more check out What is the climate in new zealand?

∙ The best interpretation of all observations is that the Solar System formed by a process called  gravitational collapse of an interstellar cloud, or nebula.

o Most nebulae in the Milky Way are made of 98% hydrogen/helium gas, and 2%  everything else.

o The hypothetical cloud that the sun formed from is called the Solar Nebula. ∙ Why are there two major types of planets? Distance from the Sun, and average temperature of  material.

What happens if a planet is further away from the sun?

o Terrestrial planets temperatures were high enough to prevent ices and light gases from  being constituents

o Jovian planets temperatures were much colder due to the greater distance from the Sun ∙ Some planet seeds eventually gained enough mass to accrete (draw in) planetesimals in their  zones, adding to their mass. Impact craters such as those on the Moon support this theory. o Jovian planets managed to gather more gas to from the surrounding disk rather than  metals or rocks, adding to their composition and making them much larger (SO FAR  AWAY FROM SUN). We also discuss several other topics like What are the characteristics of egypt and the indus valley?

∙ The Moon is thought to have formed from a massive collision of a planetesimal with a young  Earth, where a large chunk of Earth’s crust was recaptured by its gravity and continued accreting  other planetesimals until it died geologically.  

Conservation of Energy and Angular Momentum 

∙ Material falls towards a dense “seed”, pics up speed, and “crashes” into the seed, colliding with  other particles already there ???? INCREASES random thermal motions and heats the gas ∙ If the collapsing cloud had any initial rotation, as it collapses it will spin faster and faster, leading  some material to settle into a disk around a hot and dense “seed” We also discuss several other topics like How to calculate map distances from recombination data?

o Adds order to the motion of material around the forming sun

AY 101-001 Professor Buta  


∙ The further from the Sun a planet is, the less sunlight it will get and respectively, the cooler it  will become.  

o Also, the closer a planet is to the Sun, the shorter its days/years will be, and its orbital  and rotational periods will create very extreme “seasons”.  

∙ Terrestrial planets are usually comprised of layers depending on DENSITY, including a core, a  mantle, and a crust.  

o When terrestrial planets formed, most of the denser metals sank to the center (core) of  a planet and became so compressed they are indefinitely molten.

▪ This is what provides the heat for geological activity such as volcanism.  

∙ What factors have determined the appearance and structure of the different terrestrial planets? o Distance from the Sun determines how much heat a planet receives

o Size and mass determines ability of a planet to trap internal heat  

o Size+Mass+Distance from the Sun determines ability of a world to keep an atmosphere o Age determines how long geologic activity and solar heat have had to change and mold  the surface of a world We also discuss several other topics like What pertains to the process of gradually adding more of the same types of skill?

∙ Internal heat can come from conversion of gravitational protentional energy into heat when  planets were accreting, and decay of radioactive materials embedded in rock.

∙ Each terrestrial planet has a lithosphere, or rigid outer layer of cooler, low density rock that  “floats” on warmer, more “plastic” material below

o Big terrestrial planets=thin lithospheres

o Small worlds cool faster than large ones.  

∙ Convection is the movement of thermal energy; hotter, LESS dense materials will rise, while  cooler, denser materials “sink”.

o This process helps recycle all the tectonic plates on a large terrestrial body, essentially  providing the planet new material to its plate tectonics.  If you want to learn more check out What is the meaning of purines in biochemistry?

∙ Internal heat can help to generate planetary magnetic fields (produces by moving charges).  o If the charges move in a circulating pattern, the magnetic field that can be inferred is  like that produced by a bar magnet.  

o Rotation can cause swirling motions of a liquid conducting material inside a planet;  leading to a field.

o This field creates an aurora that protects us from the Sun’s harsh solar wind and deadly  radioactive waves.  

∙ Volcanic outgassing thanks to materials accreted during the birth of the planets provides worlds  with the atmospheres that they contain.  We also discuss several other topics like Is depression more common among men than women?

o Gases trapped below the surface ???? released by plate tectonics and volcanic activity ???? re-trapped by out gravity in the atmosphere.  

∙ Our atmosphere helps the magnetic field protect us from dangerous gamma and ultraviolet rays  from the Sun.  

∙ The atmosphere a world has also creates a greenhouse effect—trapping certain gases in the  planet that help to absorb and deflect certain rays, which makes a planet warmer. o Venus has a rampant greenhouse effect, making it too hot for any life to exist on its  surface.

AY 101-001 Professor Buta  

∙ Mercury is very similar to Earth’s Moon, being crater-rich with many smooth plains, and being  small in size (1/3 of Earth’s size).

∙ Speaking of the Moon, lunar maria are frozen lava plains that are dark against the white dust of  accreted planetesimals.  

∙ Mars is red in color due to iron oxide dust, and has evidence that there was previously water  millions of years ago, thanks to dry river channels and tributaries.


∙ Jupiter and Saturn are thought to have liquid surfaces under the many miles of cloud-layers that  they have acquired.

o Saturn has an atmosphere of hydrogen and helium gas.

o Jupiter has an atmosphere of ammonium hydrosulfide

▪ These clouds reflect red/brown, which the ammonia, the highest coldest layer,  reflects white.  

∙ Jupiter’s Magnetic Field—the liquid metallize hydrogen zone + rapid rotation + significant  internal heat=most powerful magnetic field in the Solar System

∙ The prominent banding as seen in images of Jupiter are the separation of the gases in its clouds  because of the planets extremely fast rotational period.

∙ The high levels of methane in the atmospheres of Neptune and Uranus cause them to take on  bluish hues.

∙ The rings of Saturn are made of billions and billions of snowball-sized planetesimals that are  trapped in orbit around the planet, and kept from accreting thanks to all of the objects orbiting  at nearly the same speeds.  

o This structure is caused by the gravity of many small moons orbiting in the rings or  larger moons orbiting outside of them.

∙ Inner edge of Cassini Division is a strong 2:1 orbital resonance with Saturn’s innermost moon  Mimas, allowing their dance to force the shape of the rings they separate.  

o Orbital Resonance—when the orbital period of one object is an integer multiple of the  period of another object

∙ Shepherd satellites are small moons which orbit just inside and outside the ring

∙ Jupiter’s immense size means it will have extremely strong gravity, which it exerts on the closest  moons, the Galilean moons.  

o The push and pull of tidal forces creates a degree of friction in all four moons, resulting  in tidal heating and ultimately geological activity.  

o The force that Jupiter exerts on Io is so strong that it warps the planet’s shape during  perihelion and aphelion, creating massive internal friction.  

o Io is the most geologically active with rampant volcanic activity.  

∙ Being part of Saturn’s moon system means that Titan receives internal friction from tidal forces,  as well as the breaking down of radioactive materials in relation to its hydrogen compounds. ∙ Titan has had lots of geological and volcanic activity, which created its methane, nitrogen, and  ethane rich atmosphere=RAMPANT GREENHOUSE EFFECT.

AY 101-001 Professor Buta  

∙ Because Titan is so far from the Sun, it is too cold for liquid water to exist; HOWEVER, liquid  methane is abundant and forms a precipitation cycle on the moon.  


∙ Asteroid—rocky “leftover planetesimals”; fragments of previously destroyed planetesimals o Most asteroids orbit the sun between Mars and Jupiter, but some are “Earth-crossing”  and others lie on Jupiter’s orbit

∙ Meteors and Meteorites— objects which fall to Earth from space.  

o Most meteors involve objects no bigger than a pebble or a pea.  

o However, a larger object (meteorite) could reach the ground and leave a sizable impact  crater.  

∙ Comets are the icey counterparts to asteroids

o The solid part of a comet is the nucleus (dirty iceberg), made mainly of ices and dust  particles; when their orbits approach the sun this ice begins to melt.

▪ This loosens the dust and creates 2 tails; one is a plasma (gas) tail, made when  the solar wind charges photons in the ice vapor; the other is a dust tail, which is  heavier so its inclined towards a planet’s orbit.

▪ Plasma tail is blue, dust tail is orangey-yellow.

o Meteor showers are caused by the third tail of a comet, which is made of large, low hanging dust particles that get burnt up in the Earth’s atmosphere.

o We can see hundreds of flashes of light at one time, as the pea-sized rocky particles are  burned away.  

∙ When a comet sublimates to create a gas/plasma tail, the ices are melting so quickly in the Sun’s  presence that they go straight from a solid to a gas (think DRY ICE).  

∙ Impact craters are proof that accretion still exists today, such as on the Moon and Mercury.  ∙ The Kuiper Belt is a donut-shaped region just beyond the orbit of Neptune that contains  thousands of icey planetesimals.

∙ Beyond this is the Oort Cloud, in which we have no idea how many comets might reside but it is  around a trillion; their orbits are randomly elliptical so the Cloud has a roughly spherical shape.

∙ What leads to the different meteorites? Shattered, differentiated asteroids from the early solar  system can account for ALL THREE types: iron (core), stony (from outer layers), and stony iron  (from in-between)


∙ Exoplanet—short for extra-solar planet, a planet which orbits a different star from the Sun; a  planet where an alien sun illuminates the daytime.

∙ We do not “see” exoplanets; planets shine by reflecting starlight, and can get lost in the glare of  their parent star.

∙ Radial Velocity Method—a planet and its star orbit their common center of mass. Even I the  planet is unseen, you can detect the wobble (small degree of movement) of the parent star  around the center of mass (also called ASTROMETRIC METHOD)

o Can be used to detect stars that have planets orbiting extremely close to them, using  precise measurements

AY 101-001 Professor Buta  

∙ Transit Method—if an exoplanet’s orbit is nearly edge-on to us, the planet will periodically pass  in front of its star, temporarily dimming it a very small amount.

o Carefully monitor a star’s brightness over an extended period; once a theorized planet  has passed by or eclipsed it at least three times, it will be labelled as a proposed  exoplanet.

o Like with the Doppler effect, the transit method is most effective if the we are edge on with an exoplanet and parent star, to view the maximum effect of brightness vs.  exoplanet motion.  

∙ The center of mass must fall between the parent star and the planet itself, because all set  bodies in a solar system have an orbit, the PARENT STAR INCLUDED!  

o The “wobble” is the orbital path of the parent star in connecting with the planet being  observed, around their SHARED CENTER OF MASS.

o If many planets are located near the parent star, its wobble will have an intricate path  thanks to multiple forces acting upon it.

∙ As discussed in previous chapters, the Doppler effect can be discerned through light  spectrums—blueshifts for an object coming closer and redshifts for an object moving further  away.

o The same can be done for a parent star in outer galaxies—as the star orbits its center of  mass, it will come closer and move further away

∙ Shifts in the red and blue ends of the spectrum will denote this, and repeated shifts will provide  data to define the movements.  

o The radial velocity curve is the tracking of said repeated shifts between this star and its  center of mass using the Doppler method.  

∙ The Doppler method can also determine a planets mass because more mass=greater  gravitational effect on the parent star=star moves faster around center of mass. o There are some tracked exoplanets that are half the mass of Jupiter but lie very close to  their parent stars, hence the name hot Jupiter.  

∙ The “goldilocks” zone is a nickname for the habitable zone of a solar system. o It is the range of planets from the Sun that could have oceans and surface life; its not  too hot, not too cold—but just right.  

∙ Planetary migration— the term used to explain how Jovian-like planets ended up near the inner  solar system of outer galaxies.  

o The gravity of a planet sends of waves of energy as it orbits the parent star. o These waves cause random material in the system to “bunch up” and now it has some  mass, and therefore a little bit of gravitational pull.

o This pull messes up the orbit of a planet and the force it exerts ends up pulling the  planet from its set orbit to be closer to the parent star.  

∙ “Free floaters” are rogue planets (a planetary mass-like object that is)—they either formed in a  solar system and were ejected or simply just never became bound to a star or brown dwarf  (star-like entity).

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