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UA / Astronomy / ay 101 / What characterizes terrestrial planets?

What characterizes terrestrial planets?

What characterizes terrestrial planets?


School: University of Alabama - Tuscaloosa
Department: Astronomy
Course: Intro To Astronomy
Professor: Ronald buta
Term: Spring 2017
Tags: Astronomy 101, astronomy, intro to astronomy, solar system, solar system astronomy, planets, planet, moons, mercury, Venus, EARTH, Mars, Jupiter, saturn, uranus, and neptune
Cost: 50
Name: AY 101 Study Guide Solar System Exam
Description: This study guide details our Solar System and its planets, moons, and other celestial entities.
Uploaded: 10/16/2017
6 Pages 162 Views 6 Unlocks

Solar System

What characterizes terrestrial planets?

∙ Made up of the Sun, 8 planets and their moons, and smaller objects such as  asteroids, meteors, comets, etc.*

∙ Formation

∙ Distribution?

o Planets revolve around the sun along a plane and in the same direction o Most planets have a vertical, counter-clockwise rotation, but Venus and Neptune rotate clockwise, which is known as having retrograde motion; Uranus rotates horizontally

∙ Two types of planets

o Terrestrials: rocky, smaller, closer to the sun, slow rotation, few  moons, dense, solid surface, no rings, small atmosphere; Mercury,  Venus, Earth, Mars

Which planets are consdiered jovians?

 Formed because the close distance to the sun heated Hydrogen  atoms too much for them to collect; rather, rocky and metallic  

elements, which are heavier and therefore slower, collected at  

the core; smaller because there are less rocky and metallic  

elements in the universe than hydrogen

o Jovians: gaseous, large, farther from the sun, fast rotation, many  moons, low density, no solid surface, rings, large atmosphere Don't forget about the age old question of What is assistive technology?

 Unlike Terrestrials, could collect Hydrogen because Jovians are  farther from the sun; could grow larger due to hydrogen’s  


 Two types of Jovians

∙ “Gas Giants”: Jupiter, Saturn

Which planet is considered earth's twin?

o Began as a rocky, metallic, and icy core, then  

began collecting hydrogen in massive quantities

∙ “Ice Giants”: Uranus, Neptune

o Also began as rocky, metallic, and icy core, but  

could not collect as much of a hydrogen  

atmosphere; this is likely because as they were  

beginning to collect the hydrogen, the sun became  

active, dispersing the remaining loose hydrogen  


∙ Asteroids have in common with planets***

∙ Some planets, such as the Earth are differentiated, or layered with the  densest materials in the center

o This likely happened to rocky planets because they were molten, which allowed denser materials to pass through the less dense materials and  settle at the core Don't forget about the age old question of In what way does violence affect journalists?

∙ Internal heat comes from residual heat from the planet’s formation  (accretion), gravitational compression, gravitational settling (when higher  density materials settled at the center), and radioactivity (ongoing, so this is  generating heat today, not residual) If you want to learn more check out Which component of language acquisition refers to grammar?

o Smaller planets lose internal heat faster

o Losing internal heat causes a planet to lose magnetic field and  therefore lose atmosphere


∙ Geologically dead planet

∙ Almost twice as big as the Moon, 40% size of Earth and 5% mass of Earth, but density is almost the same as Earth.  

∙ Rotation is 88 days and has a stronger elliptical orbit than most planets;  orientation switches each orbit

∙ Has many craters and cliffs, called scarps

∙ Large temp range, from 700 K to 150 K


∙ considered Earth’s twin, 95% of Earth’s radius

∙ Has a slow, retrograde (backwards) rotation

∙ Extremely reflective

∙ Venus is the hottest planet in the Solar System because it’s atmosphere is  extremely dense and made of mainly carbon dioxide which traps heat  through the greenhouse effect, known as a “runaway greenhouse” We also discuss several other topics like What does dorsal root ganglion mean?

∙ Has larger volcanoes than Earth’s largest mountains, and these volcanoes  generate lightening and causes SO2 levels to vary, which is evidence for us  that these volcanoes are active. We also discuss several other topics like Why was the 1970s considered the worst decade of inflation?

∙ Has no small craters due to the dense atmosphere. There are also very few  large craters, revealing lava flow is covering earlier craters across the entire  globe


∙ only planet confirmed to contain life

∙ 1,000 mi/hr rotation, 67,000 mi/hr revolution; takes light from Sun 8 min to  reach Earth, 93,000,000 miles from Sun; 24,000 mi/hr escape velocity ∙ Seismic waves are used to study Earth’s history

∙ Because the center (core) of the Earth is the densest, the Earth must have  been completely molten at some point in its past so the densest materials  could fall within the center

∙ Core is thick and made of iron and nickel. It has an inner portion that is solid  and an outer portion that is molten. Center-most temperature is close to that  of the Sun’s surface (about 5000 K)

∙ Mantle is made of basalts, silicates, and oxides. It is between the core and the crust

∙ Crust is very thin and made of tectonic plates, which is unique in our Solar  System. This causes volcanos and earthquakes to occur along the plate lines.  They are moving about 1-2 cm/year. Don't forget about the age old question of What services does mea serve?

∙ Erosion causes many land features, such as canyons, smooth plains, etc. It is  caused from running water, wind, glaciers, etc.

∙ 70% covered in water

∙ Our atmosphere is unique in that much if it is a byproduct of life (breathing,  trees); 77% Nitrogen (mainly comes from volcano, but some from biological  decay), 21% Oxygen (mainly comes from plants)

∙ Layers of the Atmosphere: troposphere (where the weather occurs, clouds),  stratosphere, mesosphere (where the ozone is located), thermosphere ∙ Heated the most at surface (heated by indirect heat coming from the Earth  itself in infrared waves, which are scattered by greenhouse gases),  stratopause (between stratosphere and mesosphere, heated by UV light  absorbed by ozone) and higher points of the thermosphere (hottest, heated  by x-rays from the Sun)

∙ Potential runaway greenhouse being developed because of an increase in  Carbon Dioxide; Ozone is being destroyed

∙ Magnetosphere surrounds the Earth, it helps us maintain our atmosphere by  protecting it from the solar wind

∙ Aurora is caused by particles from space being “caught” by our  magnetosphere and being ionized, giving off light


∙ Hit by meteors often in the past, creates craters. When the moon was  geologically active, lava flowed into large craters and formed the mare, a  smooth surface on portions of the moon.

∙ Surface is rather powdery (astronauts’ footprints), shows the moon is subject  to erosion. It has little atmosphere, so particles being dispersed from the sun  erodes the surface.

∙ Makes up a quarter of the size of Earth, 1/80th of our mass, so you would feel  weightless on the moon. Not very reflective, reflects about 7% of light.  240,000 mi away from Earth

∙ The orbit is slightly elliptical, which causes a “wobble” from our view ∙ No atmosphere, so temps range from -230ᵒ F to 260ᵒ F (100K-400K) ∙ Water ice survives at poles in deep craters because it never sees sunlight.  This is where successful moon bases could be established.

∙ The moon is outgassing H, He, and Ar. These gases move very quickly at the  high temps, and gravity is too weak to “capture” these gases.



∙ About half the size of Earth, 1/9 the mass of Earth, 2/5 the gravity of Earth,  24.6 hr day, takes 1.9 Earth years to revolve around the Sun

∙ Has 4 seasons because it has a 25ᵒ tilt

∙ Seasons are 6 months long

∙ Global dust storms are formed as part of the seasonal variations, particularly  when Mars is closest to the sun

∙ “Red Planet”, red because its surface is rusty

∙ Means less differentiation because iron is a heavier element

∙ Has massive mountains and volcanoes; Mount Olympus is 3 times taller than  Mt. Everest, sits on cliffs 4 miles tall

o These volcanoes and mountains are taller because weaker gravity  allows surface features to grow higher before being crushed toward the surface and there is no continental drift

∙ Some volcanic activity is evident because of relatively recent resurfacing, but we see no volcanic activity going on today

∙ Has a giant valley (Valles Marineris) that is bigger than the Grand Canyon in  every way, but it is not caused by erosion, as the Grand Canyon is, but rather was created by the cracking of the surface of the planet.

∙ Mars once had running water

o Found in polar caps in the form of ice; there is both water ice and CO2 ice (dry ice)

o Possible glacial flows, evident by glacier-like formations within craters ∙ Atmosphere is thin and freezing because it is losing internal heat and  therefore losing magnetic field

∙ Mainly composed of CO2

∙ Surface temp ranges from -200ᵒ to 80ᵒF

o Because of the more substantial atmosphere in the past, it is believed  that the surface was warmer in the past, and since it is also likely  water ran in liquid form, there is a possibility of life existing once on  Mars

∙ Its moons are relatively small and irregularly shaped; Phobos (30 km) and  Deimos (15 km)

o They are irregularly shaped because they don’t have much self-gravity  that would otherwise crush them into spheres

o They could possibly be captured asteroids



∙ largest planet, “gas bag”, Red Spot

∙ 11 times the size of Earth, 10 times smaller than the Sun, gravity is 2.5 times  that of Earth, smaller density than Earth’s because the mass is 318 times that of the Earth

∙ 10-hour rotation, which causes storms in its atmosphere

∙ The Great Red Spot, most famous of Jupiter’s storms, is the size of 2 Earths ∙ Different latitudes rotate at different speeds

∙ Different colored bands across surface is result of different trace elements ∙ No seasons because it only has a 3ᵒ tilt

∙ Made mainly of gas; 4 layers: visible clouds, gaseous hydrogen, liquid  hydrogen, metallic hydrogen (due to the incredibly high density), core of  metals, rocks, and hydrogen compounds (methane, ammonia, water)

∙ The metallic hydrogen creates an extremely strong magnetic field o Moons could hold life due to oceans, but the magnetic field would  catch materials and create intense radiation hitting the moons

∙ Composition is much like a star (85% H, 15% He), but it’s mass is too small to generate enough heat for fusion to occur, which is what defines a star ∙ Denser as moving to the center

∙ There are over 60 moons

o Io, Europa, Ganymede, and Callisto were discovered by Galileo, most  significant moons; all have the same face toward Jupiter, much like our  moon

o Io is the closest to Jupiter, has the most volcanic activity in the Solar  System, even though it is very small in comparison to other  

geologically dead bodies in the solar system; it is being resupplied with heat because it is close to Jupiter and being affected greatly by its  gravity (tidal heating)

o Europa was recently resurfaced and might have oceans of water in a  reservoir under the surface

o Ganymede and Callisto are the largest moons in the solar system Saturn

∙ Much like Jupiter, slightly smaller, similar composition and layering, also  rotates quickly, creating a strong magnetic field; but 3x less massive, and  colored bands are subtler

∙ 9 times the size of Earth, gravity about the same as Earth, 95 times the mass of the Earth, density of .7 gm/cc which is less than water; tilt similar to  Earth’s

∙ Revolution period of 29 years

∙ It’s moon, Titan, has an extremely thick atmosphere (4x thicker than Earth’s), life could be sustained because solid, liquid, and gaseous methane can exist  at the same place, much as water does for us

∙ Largest ring system in Solar System


∙    Radius is 4 times the Earth’s, mass 15 times Earth’s (core about 10 Earth  masses for all Jovians)

∙    Period of 84 years, 42-year day

∙    Traces of methane gives the blue color by absorbing red light, but most of the atmosphere is hydrogen

∙    Discovered in 1781

∙    Can barely see by eye

∙    Layers: visible clouds, gaseous hydrogen, and core of rocks, metals, water,  methane, and ammonia ices

∙    Rotates sideways


∙    Radius is 3.9 times the Earth’s, Mass 17 times the Earth’s, gravity only  slightly higher than Earth’s, density of 1.6 gm/cc (densest of Jovians) ∙    Period of 165 years, 18-hour day

∙    Discovered in 1846

∙    Like Uranus, methane gives blue color, but most of the atmosphere is  hydrogen

∙    The Great Dark Spot was a storm on the surface, much like the Great Red  Spot, but disappeared in the 90s

∙    Too faint to see by eye

∙    EXTREMELY similar to Uranus

∙ Moon, Triton, has an atmosphere and volcanos

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