AST CH 4

Which have more moons on average?

Jovian planets

According to our theory of solar system formation, what are asteroids and comets?

Leftover planetesimals that never accreted into planets.

List the planets of our solar system in the correct order from closest to farthest from the Sun.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Which is NOT a characteristic of the outer planets?

They have very few, if any, satellites.

The terrestrial planets are made almost entirely of elements heavier than hydrogen and helium. According to modern science, where did these elements come from?

They were produced by stars that lived and died before our solar system was born.

All four of the giant outer planets: Jupiter, Saturn, Uranus, and Neptune- have rings. T/F

True

All planets orbit the Sun in the same direction (counterclockwise as viewed from above Earth's North Pole) T/F

True

The more massive planets in the solar system tend to be less dense than the lower mass planets. T/F

True

Which planet listed below has the most extreme seasons?

Uranus

Which planet is approximately halfway between Pluto's orbit and the Sun?

Uranus, the seventh planet from the Sun

The planet in our solar system with the highest average surface temperature is _________________

Venus

Hydrogen compounds in the solar system can condense into ices only beyond the

frost line

The first few hundred million years of the solar system's history were the time of __________________ during which Earth suffered many large impacts.

heavy bombardment

Our moon was most likely formed by a collision between Earth and a Mars sized

planetesimal

Jovian Planets

primarily composed of hydrogen, helium, and hydrogen compounds; extensive ring systems; numerous orbiting moons; low average density

__________________________ allows us to determine the age of a rock

radiometric dating

Compared to terrestrial planets, jovian planets are

more massive and lower in average density

What substances existed as solid flakes within the inner 0.3 AU of the solar system before planets began to form?

none

According to modern scientific dating techniques, approximately how old is the solar system?

4.5 billion years

Where would you expect terrestrial planets to form in the solar nebula?

Anywhere between 0.3 AU and the frost line

Jovin planets

-Accreted from icy planetesimals -Formed in a region of the solar system with lower orbital speeds -Large moons formed in surrounding disks of material -Ejected icy planetesimals that are now Oort cloud comets

Terrestrial planets

-Accreted from planetesimals of rock and metal -Surfaces dramatically altered during the heavy bombardment

In which of the following ways do Pluto and Eris differ from the terrestrial and jovian planets in our solar system?

-Smaller than any of the terrestrial planets -Travel in more elliptical orbits than ay of the terrestrial or jovian planets -Less massive than any of the terrestrial or jovian planets

Solar nebula:

98% hydrogen and helium

Which of the following three kinds of objects resides closer to the Sun on average?

Asteroids

Which lists the major steps of solar system formation in the correct order?

Collapse, condensation, accretion

What is the main reason that Earth's composition is different from Jupiter's?

Compared to Jupiter, Earth formed in a hotter region, where only rocks and metals could exist as solids

Which of the following did not occur during the collapse of the solar nebula?

Concentrating denser materials nearer the Sun

Suppose that the Sun shrank in size, but its mass remained the same. What would happen to Earth's orbit?

Earth's orbit would be unaffected

All comets orbit the Sun in the same direction as the planets. T/F

False

All the planets in the solar system have at least one moon. T/F

False

Which of the following types of material can condense into what we call ice at low temperatures?

Hydrogen compounds

According to our present theory of solar system formation, which of the following explains why the solar system nebula ended up with a disk shape as it collapsed?

It flattened as a natural consequence of collisions between particles in the nebula.

What's the leading theory for the origin of the Moon?

It formed from the material ejected from Earth in a giant impact

What do we mean by the frost line when we discuss the formation of planets in the solar nebula?

It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense

What substances were found within the inner 0.3 AU of the solar system before planets began to form?

Rocks, metals, hydrogen compounds, hydrogen, and helium, all in gaseous form

Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestrial planets?

Terrestrial planets will likely be located nearer the planetary system's star than any Jovian planets

What is the giant impact hypothesis for the origin of the Moon?

The moon formed from material blasted out of Earth's mantle and crust by the impact of a Mars-sized object.

Suppose you start with 1 kilogram of a radioactive substance that has a half-life of 10 years. Which of the following statements will be true after 20 years pass?

You'll have 0.25 kilogram of the radioactive substance remaining.

Mars was formed by the __________________ of smaller objects.

accretion

Suppose the solar nebula had been too warm for ices to condense anywhere. If a planet had still formed at Jupiter's location, it most likely would have

been similar in composition to Earth, with a much smaller mass than the real Jupiter

The jovian planets contain large abundance of hydrogen and helium because

beyond the front line, the gravity of large, ice-rich planetesimals captured the abundant H and He gas

Ice can form from a gas through the process of

condensation

Planetary orbits in our solar system are

fairly circular and in the same plane

As the solar system nebula collapsed under its own gravity

it heated and spun up

Because of the temperatures in the protoplanetary disk,

rocks and metals froze in both the inner and outer regions, and ice froze only in the outer region

The jovian planets are thought to have formed as gravity drew hydrogen and helium gas around planetesimals made of

rocks, metals, and ices

Terrestrial Planets

small size; solid, rocky surface; located within the inner solar system

Our solar system was created by the gravitational collapse of the

solar nebula

The era of planet formation ended when the remaining hydrogen and helium gas of the solar nebula was swept into interstellar space by the

solar wind

As the solar nebula collapsed, it became a disk because

the overall rotation of the nebula plus collisions between particles made the particles go in more or less the same direction

The planets in our solar system are thought to have come from

the same cloud of gas and dust in which the Sun formed

If the solar nebula initially had no angular momentum

there would not be any planets orbiting the Sun

Suppose the solar nebula had cooled much more before the solar wind cleared away the remaining gas. In that case, the terrestrial planets likely would have ended up:

with a higher abundance of hydrogen compounds and larger size