Unit 4

Question 1

Mercury (brief)

Answer 1

Terrestrial planet

more typical of the inner planets than watery surface of earth

No atmosphere

Question 2

Dangerous place

Answer 2

There is a lot of cratering records in our solar system

on planets and moons (natural satellites)

Question 3

Terrestrial planets

Answer 3

when these planets formed they were hot and molten (liquid rock)

Differentiation acured

Question 4

Differentiation

Answer 4

As planets cool the denser material sinks towards the center of the planet and forces lighter materials to float to the surface

Question 5

The outer solar system

Answer 5

4 giant planets
* Jupiter
* Saturn
* Uranus
* Neptune

While harder to reach still the subject of many successful missions

Question 6

Planet Types

Answer 6

Terrestrial
* small and rocky
* orbit close to the sun

Jovian
* much larger and gaseous
* orbit much further out

Question 7

Jovian Worlds

Answer 7

Mostly made of hydrogen and helium, gases we see in the sun

when we see these planet it is their atmosphere we observe

Many hydrogen compounds in the atmosphere

Question 8

Ganymede

Answer 8

Jupiters Moon

Largest satellite

Question 9

Jovian vs Terrestrial planets

Answer 9

A big difference between Jovian and Terrestrial planets is the number of natural satellites

Jovian worlds have lots more satellites Jupiter has 95 orbiting around it

The terrestrial planets have few if any satellites

Question 10

Impact today

Answer 10

In 1994 Jupiter sustained impacts from over 20, 1km size rocks
* moving at over 60 km/s from gravitationally disrupted comet

If any were to hit Earth, significant devastation would occur

Question 11

Dwarf planet

Answer 11

Pluto First discovered as a planet
* Then late was proven to be considered a Dwarf planet (Smaller than our moon)
* Has active ice volcanoes

Unlike planets we are not sure how many dwarf planets exist

this is a new category of objects (2006)

Question 12

Rings

Answer 12

All 4 Jovian worlds possess rings
* some better developed (brighter and larger)

Made up of rock and since, normally only a few centimeters in size but can range up to meters

Question 13

Asteroids (Minor planets)

Answer 13

Are everywhere

Number in the millions

some are 100 Km in diameter

small pieces of rock that do not become part of planet during the solar system formation 4.5 billion years ago

Question 14

Comets

Answer 14

Also leftover materials from the formation of the solar system

only a few kilometers in diameter

different from asteroids
* they contain a lot more volatile materials (water, ice, methane, carbon dioxide)
* when heated they generate very bright and long tails

Question 15

Age determination

Answer 15

Determined by counting the number of creates in a given area
* More means older
* Only works if the surface is not geologically active

Using radioactive dating
* Every radioactive element has a half-life
* Original material is often called the parent, and what it decays into is the daughter

Question 16

Solar system formation

Answer 16

Our solar system is formed from a large cloud of dust and gas (giant molecular cloud (GMC))
* As it began to spin, it flattened into think disk (Pancake)
* in the center the acceleration was fast forming our proto-star

Planetesimals
* smaller pieces of rock began to collide and grow larger forming protoplanets

Inner solar system was warming up forcing gasses towards the outer solar system beyond the ice-line (Asteroid belt today)

the Jovian planets grew larger form accretion and the abundant supply of volatiles

the terrestrial plants remained small(ish) and were comprised of refractory elements (higher melting points)

when the sun started nuclear fusion in tits core, solar system formation stopped

Question 17

Our moon

Answer 17

very similar to mercury
* Almost the same size
* physical appearance

No atmosphere because of low gravity (1% Earth mass)

lacking dense metals and no appreciable core

overall density similar to Earth’s crust

“Dead” world

Question 18

Lunar exploration

Answer 18

ALSEP (Apollo Lunar Science Experiment Packages) operated for many years

Many countries have also focuses on the moon
* Japan, India, China, ESA have all sent probes to the moon

Question 19

Our moons appearance

Answer 19

moon formed as the solar system was forming ~4.5 billion years ago

83% Lunar highlands
* composed of low density anothrosites

17% Flat Maria
* very powdery because of years of impacts
* dust is one of the biggest concerns for astronauts as they are sharp

Question 20

Our moon Origin

Answer 20

Fission theory
* The moon was once part of Earth, but somehow separated from it early in their history

Sister theory
* The moon formed together with (but independent of) Earth, as we believe many moons of the outer planets formed

Capture Theory
* The moon formed elsewhere in the solar system and was captured by Earth

Giant impact hypothesis (Probably correct)
* In essence, a large shearing impact removed a substantial portion of earth’s crust that then colled to form our moon

Question 21

Mercury

Answer 21

Its proximity to the sun makes mercury very hot

Its small size means it cannot maintain an atmosphere

Density suggests a composition similar to Earth with a much larger core relative to its size

weak but significant magnetic field

dominated by a metallic core same size as our moon

orbital period of 3:2
* spins on its axis 3 times for every 2 orbital periods around the sun

Question 22

Mercury’s Appearance

Answer 22

Heavily cratered with water ice, high cliffs and plains of dried lava

No Natural satellites

Question 23

Mercury formation

Answer 23

Formed in a similar way to Earth (Venus and Mars too)

lack of crustal material suggest dramatic collision early on, ripping away material

Question 24

Venus

Answer 24

Apart from the sun and the moon Venus is the brightest

called the Morning Star or Evening Star

its perineal cloud gives its brightness
* makes surface feature identification impossible from Earth

Rotates East to West
* not the usual west-to-east

Takes 243 days to complete a rotation

A year on Venus is 225 days long

Dense atmosphere (90 * Earths)

Surface temp of 450C

Acid Rain

Question 25

Venus Surface

Answer 25

Thousands of volcanoes * some may be active 75% of the surface is a lowland plain of lava

Question 26

Venus atmosphere

Answer 26

Dominated by carbon dioxide (96%) with some nitrogen (3.5%) Clouds of sulphuric acid persist between 30 and 60km above the surface

Question 27

Venus Evolution/History

Answer 27

Earth-like early in its history with water on the surface Closer to the sun and thus a modest increase in temperature resulted in evaporation leading to a runaway greenhouse effect and the current environment

Question 28

The outer planets

Answer 28

The 2 gas giants, 2 ice giants Colder region of the solar system composition includes hydrogen and helium (dominant) but also ice (water, methane, ammonia) and rocks (silicate metals, etc. ) Elements formed preferentially with hydrogen These 4 planets are much more massive than terrestrial planets The clouds are what we see when observing the outer planets Lots of ammonia crystals in Jupiter and Saturn clouds, and more methane for Neptune Seasons on these worlds vary from extreme on Uranus to non-existent on Jupiter Uranus * Rotates on its side

Question 29

Jovian planet interiors

Answer 29

The interior structure of Jupiter and Saturn are similar Uranus and Neptune being less massive the cores are small and not easily defined by Uranus and Neptune's cores are larger than Jupiter and Saturn All 4 have leftover heat from the formation * Lots of insulation to trap heat * some heat from contractions as well All 4 planets rotate very quickly (Jupiter in 10 hours)

Question 30

Cloud top Appearance

Answer 30

Internal heat sources, rapid rotation, convection, and mixing of a lot of chemical interactions occur giving rise to the carried and colorful appearances

Question 31

Jovain versus terrestrial planets

Answer 31

Density, composition, size, location, etc. All outer solar system planets have numerous satellites orbiting around them each possesses a ring system.

Question 32

Moons (Satellites)

Answer 32

over 200 are currently known to orbit the 4 outer planets Highlights * Ganymede is the largest satellite in the solar system * Io is the most volcanic object in the solar system\ * Europa has a sub-surface ocean of warm water (surface organic material) * Titan orbiting Saturn has a denser atmosphere than Earth and has liquid methane on its surface * The Triton (Neptune's largest moon)

Question 33

Pluto

Answer 33

The size of pluto was not established until 1978 its mass was found to be .2% of Earth it's so little its a different category of object than a planet * it's a Dwarf planet its a rocky icy mix similar to many solar system satellites its reflective surface has frozen methane, nitrogen, and carbon monoxide gases it * has a very thing atmosphere

Question 34

Planet definition

Answer 34

Orbit the sun Be round Have cleared out (Dominates) its orbit

Question 35

Rings

Answer 35

Another obvious distinction between the terrestrial and jovian worlds is the presence of a ring system the ring's systems are quite different from each other with Saturn being the brightest and most extensive and Jupiter being the least developed

Question 36

Ring Composition

Answer 36

Made of rock and icy particles by the billion * they orbit in the planet's equatorial plane Did they originate as a breakup of an asteroid or small or are the ring's leftover material unable to form a satellite? All are very thine compared to their diameters large and smaller "shepeherding" satellites gravitationally manage the motion of the ring particles