Exam 2 - The Jovian, Gas-Giant Planets, their Moons, and their Rings

What are volatile ices?

hydrogen compounds, such as methane CH4, ammonia NH3, and water H2O

What was the frost line during the formation of the Solar System?

the precise distance from the Sun beyond which volatile ices were able to condense in addition to metal and rock

What were the cooler, outer regions of the protoplanetary disk more abundant in?

Volatile ices are more abundant than metal and rock and were able to condense alongside these materials

What did the condensing of volatile ices, metal and rock allow?

It allowed the formation of large planetesimals composed of volatile ices, metal, and rock

How did these planetesimals grow larger?

They grew larger through accretion, eventually becoming big enough to pull themselves into spherical shapes due to self-gravity

As the planetesimals continued to grow, what happened?

They differentiated, with dense metals sinking to the core, volatile ices rising to the surface, and rock settling in between them.

Why is the term "gas-giant" misleading?

While the outer layers of these planets are predominantly composed of hydrogen and helium gas, their strong gravity compresses these gases into exotic densities within their deep interior layers.

What is below the hydrogen and helium gas?

Layers of dense liquid hydrogen

What is still deeper than the layers of dense liquid hydrogen?

Layers of metallic hydrogen, followed by even denser volatile ices

What is metallic hydrogen?

electrically conductive hydrogen

What is beneath the layers of volatile ices?

A high density layer of rock, and at the core, the most dense metallic core

What is involved in the final stage formation for jovian planets?

The gravitational attraction of large amounts of hydrogen and helium gas that fell onto the forming planet

What happened as this material collapsed?

it began to rotate faster to conserve angular momentum, leading to the fast rotation of the gas giants

What did the rapid rotation result in?

the planets became severely oblate

What is oblateness?

bulging at the equator and flattened at the poles

What are the fast rotation's of the jovian gas giant's visible from?

Photographs or through telescopes due to their pronounced equatorial bulges

What do the fast rotation of these planet's generate?

Circulating currents of electrically conducting hydrogen in their deeper layers, which generates extremely powerful magnetic fields.

What is the smaller disk around the forming gas-giant called?

Protolunar disk

What does the protolunar disk eventually give rise to?

Large and medium-sized moons in orbit around the planet

What is the process of the formation of large and medium-sized moons?

As these baby moons orbited the planet, they grew larger through a process called accretion. These collisions caused the baby moons to increase in size, and as they grew, their self-gravity became strong enough to pull them into spherical shapes, transforming them into medium-sized and large moons.

What is accretion?

gaining mass by sticking to material along their orbits

True or False: Many of the large and medium moons of the Jovian planets orbit their parent planet in nearly the same plane with nearly circular orbits and in the same direction

True

True or False: the immense mass of these planets allows them to gravitationally capture asteroids, particularly those that Jupiter's gravity pulls out of the asteroid belt

True

What is the 5th planet from the Sun?

Jupiter

What is the largest and most massive planet in the Solar System?

Jupiter

What is Jupiter's orbital period around the Sun?

Roughly 12 Earth years

________'s mass is so immense that it surpasses the combined mass of all the other planets, their moons, asteroids, meteoroids, comets, and dust in the Solar System.

Jupiter

How much bigger is the Sun compared to Jupiter?

Roughly 1000 times Jupiter's mass

How much of the Solar System's mass is contained in the Sun?

99.9%

How much of the Solar System's mass is contained in the Jupiter?

Around 0.1%

Because Jupiter has a tremendous mass, Jupiter exerts tremendous......

gravity

The _______ is the one and only one reason that holds the Solar System together

Sun

Jupiter's gravity perturbs the orbits of the other planets, causing orbits to shift from

more elliptical to less elliptical

What is orbital precession?

elliptical orbits of planets slowly rotate over time

How did Jupiter's gravity influence Earth's orbit in a cycle of roughly 100,000 years?

It contributed to the major glacial periods of the current Ice Age

What is an example of Jupiter's gravitational influence being powerful enough to affect comets?

In 1992, it changed the orbit of comet Shoemaker-Levy and even caused it to break apart into more than twenty fragments. These fragments, unable to escape Jupiter's gravity, collided with the planet in 1994.

Most asteroids in the Solar System orbit the Sun within the asteroid belt, located between the orbits of....

Mars and Jupiter

How do asteroid's become small moons orbiting the Jovian gas-giant planets?

If an asteroid's orbital period has a simple ratio with Jupiter's—such as 1:2 or 2:5—then the asteroid's position relative to Jupiter repeats periodically. As this happens, Jupiter's gravity exerts a periodic tug on the asteroid, gradually pulling it from the asteroid belt. Over time, these periodic gravitational interactions can lead Jupiter to pull the asteroid out of the belt completely.

What are Kirkwood gaps?

When we graph the number of asteroids in the asteroid belt against their orbital periods around the Sun, we observe distinct gaps in the data at certain orbital periods.

When do Kirkwood gaps occur?

They occur at periods that are in simple ratio with Jupiter's orbital period, indicating the influence of Jupiter's gravity.

Who were these gaps first identified and explained by?

American astronomer Daniel Kirkwood

What are Trojan asteroids?

A peak in the graph at the 1:1 orbital period ratio, where asteroids share the same orbital period around the Sun as Jupiter. This means these asteroids are orbiting the Sun at the same distance as Jupiter but at specific positions relative to the planet and form two distinct groups

One group of the Trojan asteroids orbits the Sun ____ degrees ahead of Jupiter, and the other group orbits the Sun ____ degrees behind Jupiter

60

the Trojan asteroids are locked orbiting the Sun at the ____ of the combined gravitational fields of the Sun and Jupiter

the 4th and 5th Lagrangian points

What is the fastest-rotating planet in the Solar System, spinning more than twice as fast as Earth?

Jupiter

What has rapid rotation did to Jupiter?

It caused Jupiter to be severely oblate

Jupiter's rapid rotation has divided its atmosphere into many prevailing winds, which appear as....

cloud bands

There is a massive storm in Jupiter's southern hemisphere called the....

The Great Red Spot

What's the size of the Great Red Spot?

Roughly two Earth diameters long and one Earth diameter wide

When was the Great Red Spot first observed through telescopes?

1830

Does Jupiter have a ring system?

Yes, but it is very weak

How many moons does Jupiter have?

About 100 moons

What are the four of Jupiter's moons that are enormous as compared with the other moons?

Galilean moons

The four Galilean moons in the correct order from closest to Jupiter to furthest from Jupiter are...

Io, Europa, Ganymede, and Callisto

What are the Galilean moons named after?

The various lovers of the ancient mythological god Jupiter (Zeus)

True or False: All of Jupiter's moons have icy outer layers.

False: Io does not have an icy outer layer

What does it mean that these 4 moons are tidally locked to Jupiter?

Their rotational periods are equal to their orbital periods. As a result, they always show the same side to Jupiter as they orbit it

True or False: Each of these moons is massive enough to have differentiated into layers, with a metallic core surrounded by less dense rock.

True

What is the Jovian System analogous to?

The entire Solar System

The two different categories of moons depend on Jupiter's........

intense gravity

What are the two inner moons of Jupiter?

Io and Europa

What are the two outer moons of Jupiter?

Ganymede and Callisto

What makes Io the most volcanically active world in the entire Solar System?

Jupiter's gravity causes constant tidal forces on Io, leading to the melting and movement of rocks within its interior. These forces create immense volcanic activity

The mechanism of geologic activity on Io is clearly not plate tectonics, it is the gravitational tidal forces from Jupiter. We will call this mechanism

strong tidal heating

Why are there no visible impact craters on Io's surface?

Lava extrusions and volcanic eruptions occur frequently; although asteroids and comets do collide with Io, their impact craters are quickly covered by the lava.

Jupiter's gravity has succeeded in cracking the ice that covers Europa. This mechanism is similar to tidal heating but weaker. We will call this mechanism

weak tidal heating

What has Jupiter's gravity done to Europa?

It has fractured the icy surface

There is evidence of cryovolcanoes on Europa, what are they?

volcanoes that erupt ice instead of molten rock

Why is Ganymede, the large-sized outer moon, geologically inactive?

It is much less subject to Jupiter's gravity compared to the inner moons

Ganymede surface has heavily cratered older regions and sparsely cratered younger regions similar to

Mercury and the Moon

What is the largest moon in the Solar System?

Ganymede

What are the differences between Ganymede and Mercury?

Ganymede surpasses Mercury in size, though its mass is significantly smaller

What is the most heavily cratered world in the Solar System?

Callisto, the large-sized outer moon and furthest of the four Galilean moons

Nearly every square ____ of Callisto is covered with impact craters

kilometer

What is the fifth planet from the Sun and the second of the jovian, gas-giant (outer) planets?

Saturn

What is Saturn's orbital period?

Roughly 30 years

What is the second-largest and second-most massive planet?

Saturn

Saturn is tenuous (low density) since it is composed of mostly

hydrogen and helium

What is the most tenuous (least dense) planet in the entire Solar System?

Saturn

True or False: Saturn would float in water

True

The most dense planet in the Solar system happens to be

Earth

How many moons does Saturn have?

Over 100 moons, most are small in size

What is Saturn's one large-sized moon?

Titan

How many medium-sized moons does Saturn have?

6

What are the 7 moons listed in order from closest to Saturn to furthest from Saturn?

Mimas, Enceladus, Tethys, Dione, Rhea, Titan, and Iapetus

What has Saturn's gravity done to Enceladus?

It has fractured the ice covering the moon and melted some of the ice into liquid water

True or False: Enceladus has cryovolcanoes

True

True or False: Mimas is geologically alive

False: Mimas is dead, despite its proximity to Saturn

What is the enormous crater called on Mimas?

Herschel crater

Who discovered the Herschel crater?

British astronomer William Herschel

What would have happened to Mimas had the impact that formed the Herschel crater been moving just a little faster or been slightly more massive?

It would have been powerful enough to obliterate Mimas

What is the nickname for Mimas?

Death Star Moon

The Herschel crater gives Mimas the appearance of the

Death Star from Star Wars`

What is the nickname for the Herschel crater?

Darth Crater

What are the medium-sized outer moons of Saturn that are geologically dead?

Tethys, Dione, and Rhea

What is the massive crater on Tethys called?

The Odysseus crater

What is the second-largest moon in the entire Solar System, second only to Ganymede?

Titan

Titan is so enormous that it's even larger than planet.....

Mercury

Titan's atmosphere is mostly

nitrogen, there is an abundance of volatile ice with virtually no oxygen

What is Saturn's outermost medium-sized moon?

Iapetus