Question 1

What could have caused the proto-Jovian planets to grow very hot?
A)heat from the Sun
B)radioactivity of light elements, such as hydrogen and helium
C)the in-falling of material at high velocity
D)collisions with large planetesimals

Accepted Answer

The proto-Jovian planets grew very hot primarily due to the in-falling of material at high velocity, which released gravitational energy as heat.

Question 2

Based on current observations,which of the following has a heavy element core and a very compressed liquid layer and atmosphere,both composed mostly of hydrogen?
A)Jupiter
B)Pluto
C)Venus
D)an asteroid

Accepted Answer

Jupiter has a heavy element core and a very compressed liquid layer and atmosphere composed mostly of hydrogen. This is based on current observations and scientific studies of the gas giant planet. None of the other options mentioned have similar characteristics to Jupiter.

Question 3

The age of the solar system is believed to be approximately 4.6 billion years.On what data is this estimate based?
A)samples of proto-solar nebula
B)samples of the solar wind
C)crater counts on Earth
D)isotope ratios in meteorites

Accepted Answer

The age of the solar system is believed to be approximately 4.6 billion years based on the isotope ratios found in meteorites, which have remained unchanged since the formation of the solar system.

Question 4

Which one of the following objects is most like the planetesimals that formed in the solar nebula?
A)Vesta
B)Earth
C)Saturn
D)Venus

Accepted Answer

Vesta is a protoplanet that formed early in the solar system's history by the accumulation of smaller planetesimals. Therefore, it is the most like the planetesimals that formed in the solar nebula. Earth, Saturn, and Venus were formed later by accretion of these protoplanets and are larger and more differentiated.

Question 5

Why was the Tagish Lake meteorite important?
A)It was recovered only days after it fell to Earth.
B)It was the first meteorite recovered in Canada.
C)Signs of life were discovered deep inside it.
D)Its large crater showed that cratering still occurs on Earth.

Accepted Answer

The Tagish Lake meteorite was important because it was recovered only days after it fell to Earth, which allowed scientists to study it before it could be heavily weathered or contaminated by Earth's environment.

Question 6

The terrestrial planets are thought to have formed by accreting solid planetesimals,all with about the same composition.What does this mean?
A)They were initially molten, forming an iron core first, then they accreted a silicate crust later.
B)They were initially molten, forming a silicate core first, then they accreted an iron crust later.
C)They were initially collections of solid particles, which melted, then differentiated into a high density iron metal core and low density silicate crust.
D)They were initially collections of solid particles, which melted, then differentiated into a high density silicate core and low density iron metal crust.

Accepted Answer

The terrestrial planets formed from solid particles that melted and differentiated into a dense iron core and a less dense silicate crust.

Question 7

Why would the larger planetesimals have grown faster than the smaller planetesimals?
A)They were moving faster in their orbits than the smaller planetesimals.
B)Their stronger gravity would pull in more material.
C)There was more material located near them that could be accreted.
D)The smaller planetesimals were covered by a layer of material that was lost during collisions.

Accepted Answer

Larger planetesimals have stronger gravity, which would pull in more material and allow them to grow faster than smaller planetesimals.

Question 8

Which of the following is believed to form part of the current atmosphere of the Earth?
A)the remnants of the original hydrogen and helium gas from the solar nebula attracted by the protoplanet
B)the result of the melting and vaporizing of the glaciers from the last ice age
C)gases that were outgassed from the heated rocks sometime after the planet formed
D)hydrogen and helium from a collision between the Sun and another star

Accepted Answer

The gases in the Earth's current atmosphere are believed to be the result of outgassing from heated rocks sometime after the planet formed.

(Note: A is incorrect because the original hydrogen and helium gas would have escaped due to the planet's low gravity. B is incorrect because the melting and vaporizing of glaciers would not contribute significantly to the composition of the entire atmosphere. D is incorrect because a collision between the Sun and another star is unlikely to have occurred.)

Question 9

According to the condensation sequence,what should condense as solids closest to the Sun?
A)hydrogen and helium
B)metals and metal oxides
C)silicates
D)ices of water, methane, and ammonia

Accepted Answer

According to the condensation sequence, metals and metal oxides condense first as solids closest to the Sun due to their high melting points. As we move away from the Sun, the temperature decreases and other compounds like silicates and ices of water, methane, and ammonia can condense. However, hydrogen and helium, being gases, do not condense into solids at the temperatures found close to the Sun.

Question 10

What is the main improvement of the Kepler spacecraft compared to other planet-finding methods?
A)Kepler can detect signs of life on planets.
B)Kepler can detect planets outside the Milky Way.
C)Kepler can detect many more planets.
D)Kepler can detect much smaller planets.

Accepted Answer

Kepler's main improvement compared to other planet-finding methods is its ability to detect much smaller planets, even those as small as Earth-sized. Other methods often rely on detecting the gravitational wobble of a star caused by the presence of a planet, which is much more difficult to observe for smaller planets.

Question 11

How is the density different in different interior regions of a terrestrial planet?
A)higher density core and lower density mantle
B)lower density core and higher density mantle
C)there is no way to measure changes in interior density
D)there is no separation according to density

Accepted Answer

Typically, the core of a terrestrial planet is composed of denser materials such as iron and nickel, while the mantle is composed of less dense materials such as silicates. Therefore, the core has a higher density compared to the mantle.

Question 12

-The diagram illustrates the radioactive decay of Potassium (⁴⁰K),which has a half-life of 1.3 billion years.If a lunar rock is found that currently contains 5 grams of ⁴⁰K,and it is determined that the sample contained 20 grams when it was formed,how old is the lunar rock?
A)2.6 billion years
B)3.9 billion years
C)5.2 billion years
D)6.5 billion years

Accepted Answer

The rock originally had 20 grams of ⁴⁰K and now has 5 grams. This means it has gone through two half-lives (20g to 10g to 5g). Since each half-life is 1.3 billion years, the rock is 2.6 billion years old (1.3 billion years x 2).

Question 13

If a star is found with five planets orbiting it,and a process like that described in the solar nebula theory formed the planets,which of the planets would be expected to have the greatest uncompressed density?
A)the one farthest from the star
B)the one with the greatest mass
C)the one with the greatest radius
D)the one closest to the star

Accepted Answer

According to the solar nebula theory, planets form from the accretion of solid particles and the subsequent growth of planetesimals. As these planetesimals grow, they start to gravitationally attract gas in the surrounding protoplanetary disk. The gas that is accreted onto the planetesimals contributes to the planet's overall mass and also compresses the solid material, increasing its density. 
Therefore, the planet closest to the star would experience the greatest amount of gravitational attraction from the gas and dust in the protoplanetary disk, and would therefore have the greatest amount of compression and the highest uncompressed density.

Question 14

Why is 51 Pegasi so important?
A)because it is a pulsar with planets orbiting around it
B)because it is a star with a planet that is known to support intelligent life
C)because it is the largest satellite of Jupiter and is suspected to have liquid oceans
D)because it is the first star similar to our Sun that was found to have a planet orbiting it

Accepted Answer

51 Pegasi is important because it was the first star similar to our Sun that was found to have a planet orbiting it. This discovery opened up new possibilities in the search for exoplanets and greatly advanced our understanding of planetary systems beyond our own.

Question 15

Select the answer below where the grains are correctly matched with the location where they condensed from the solar nebula.
A)icy grains near the present orbit of Mercury
B)metallic grains near the present orbit of the Earth
C)icy grains beyond the present orbit of Jupiter
D)metallic grains beyond the present orbit of Jupiter

Accepted Answer

Icy grains condensed further out from the Sun, where temperatures were low enough for water to freeze and solidify into ice. Jupiter is located beyond the "frost line," which marks the boundary between the inner, rocky planets and the outer, gas and ice giants. Therefore, icy grains condensed beyond the present orbit of Jupiter.

Question 16

Suppose that Mercury grew to its present size in 1 million years,through the accretion of particles averaging 100 g each.On average,how many particles did Mercury capture each second? Note: Mercury has a mass of 3.3×10²³ kg and a radius of 2439 km.
A)about 67 particles per second
B)about 100 million particles per second
C)about 100 billion particles per second
D)about 3.3×10²¹ particles per second

Accepted Answer

To find the number of particles captured per second, divide Mercury's total mass by the mass of each particle, then divide by the total number of seconds in 1 million years. This calculation results in approximately 100 billion particles per second.

Question 17

How do debris disks and planet-forming disks differ?
A)Debris disks have higher density than planet-forming disks.
B)Debris disks contain larger amounts of gas than planet-forming disks.
C)Debris disks are found around older stars than those with planet-forming disks.
D)Only debris disks are expected to be affected by the gravity of planets within them.

Accepted Answer

Debris disks are often found around older stars that have already formed planets, whereas planet-forming disks are found around younger stars that are still in the process of forming planets. Debris disks are also composed mainly of smaller, rocky or icy debris left over from planet formation, while planet-forming disks contain gas and dust that can clump together to form larger planetesimals. Choice A and B are incorrect, as debris disks typically have lower density and less gas than planet-forming disks. Choice D is partially correct, as planets can affect the structure of debris disks, but they can also affect the formation of planets within planet-forming disks.

Question 18

Where in our solar system do we find the planet with the greatest uncompressed density?
A)Uncompressed density is greatest for the Jovian planets.
B)Uncompressed density is greatest for the planets closest to the Sun.
C)Uncompressed density is greatest for the planets farthest from the Sun.
D)Uncompressed density is greatest for the planets with the largest mass.

Accepted Answer

The planet with the greatest uncompressed density is Earth, which is one of the planets closest to the Sun.

Question 19

The planets all lie in nearly the same plane,resulting in a disk-like structure for the solar system.What is believed to be the reason for this disk-like structure?
A)The solar nebula from which the planets formed collapsed into a disk-like structure.
B)The bipolar flow from the young Sun cleared all material out of the nebula except the material in the disk.
C)Jupiter's gravity was great enough to pull all of the other planets to the plane of its orbit.
D)The Milky Way galaxy from which the planets condensed has a disk-like structure.

Accepted Answer

The most accepted explanation for the disk-like structure of the solar system is that it resulted from the solar nebula collapsing into a disk-like structure. The solar nebula was a cloud of gas and dust that collapsed due to gravitational forces and formed the Sun and the planets. As the cloud rotated, it flattened into a disk-like structure due to conservation of angular momentum. This disk-like structure then led to the formation of the planets, which all orbit in nearly the same plane.

Question 20

On a photograph of the Earth's moon,the Moon measures 30 cm in diameter and a small crater measures 0.2 cm.The Moon's physical diameter is 1738 km.What is the physical diameter of the small crater?
A)about 12 km
B)about 120 km
C)about 350 km
D)about 1738 km

Accepted Answer

The scale of the photograph is 1738 km / 30 cm. Using this scale, the physical diameter of the crater is (0.2 cm * 1738 km) / 30 cm = 11.586 km, which is approximately 12 km.

Quiz 12: The Origin of the Solar System

What could have caused the proto-Jovian planets to grow very hot?

Based on current observations,which of the following has a heavy element core and a very compressed liquid layer and atmosphere,both composed mostly of hydrogen?

The age of the solar system is believed to be approximately 4.6 billion years.On what data is this estimate based?

Which one of the following objects is most like the planetesimals that formed in the solar nebula?

Why was the Tagish Lake meteorite important?

The terrestrial planets are thought to have formed by accreting solid planetesimals,all with about the same composition.What does this mean?

Why would the larger planetesimals have grown faster than the smaller planetesimals?

Which of the following is believed to form part of the current atmosphere of the Earth?

According to the condensation sequence,what should condense as solids closest to the Sun?

What is the main improvement of the Kepler spacecraft compared to other planet-finding methods?

How is the density different in different interior regions of a terrestrial planet?

-The diagram illustrates the radioactive decay of Potassium (⁴⁰K) ,which has a half-life of 1.3 billion years.If a lunar rock is found that currently contains 5 grams of ⁴⁰K,and it is determined that the sample contained 20 grams when it was formed,how old is the lunar rock?

If a star is found with five planets orbiting it,and a process like that described in the solar nebula theory formed the planets,which of the planets would be expected to have the greatest uncompressed density?

Why is 51 Pegasi so important?

Select the answer below where the grains are correctly matched with the location where they condensed from the solar nebula.

Suppose that Mercury grew to its present size in 1 million years,through the accretion of particles averaging 100 g each.On average,how many particles did Mercury capture each second? Note: Mercury has a mass of 3.3×10²³ kg and a radius of 2439 km.

How do debris disks and planet-forming disks differ?

Where in our solar system do we find the planet with the greatest uncompressed density?

The planets all lie in nearly the same plane,resulting in a disk-like structure for the solar system.What is believed to be the reason for this disk-like structure?

On a photograph of the Earth's moon,the Moon measures 30 cm in diameter and a small crater measures 0.2 cm.The Moon's physical diameter is 1738 km.What is the physical diameter of the small crater?