Question 1

What observation made of other stars seems to suggest the solar nebula theory is correct
A)Stars are found to exist more often in binaries than by themselves.
B)Protostars are seen to radiate much of their light at infrared wavelengths.
C)Nearby stars tend to be low-mass red dwarfs.
D)Young stars are found to have hot disks that surround them.

Accepted Answer

The observation that young stars have hot disks that surround them supports the solar nebula theory, which suggests that planets form from a disk of gas and dust surrounding a young star.

Question 2

On a photograph of the 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 1738 km
B)about 12 km
C)about 520 km
D)about 350 km
E)about 3.5 km

Accepted Answer

The physical diameter of the small crater can be found using a proportion based on the scale of the photograph. Since 30 cm on the photo represents 1738 km in reality, 0.2 cm would represent (0.2/30) * 1738 km, which calculates to approximately 11.59 km, rounding to about 12 km.

Question 3

51 Pegasi is important because
A)it is a pulsar with planets orbiting around it.
B)it is a star with a planet that is known to support intelligent life.
C)it is the largest satellite of Jupiter.
D)it is the largest known asteroid.
E)it is the first star like our Sun that was found to have a planet orbiting it.

Accepted Answer

51 Pegasi is the first star like our Sun that was found to have a planet orbiting it, marking a significant discovery in the search for exoplanets outside of our solar system. This discovery opened up the field of exoplanet research and has led to the discovery of thousands of other exoplanets.

Question 4

Part of the current atmosphere of Earth is believed to be
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)composed primarily of hydrogen and helium.
D)composed of gases that were outgassed from the heated rocks sometime after the planet formed.
E)the result of a collision between the Sun and another star.

Accepted Answer

The current atmosphere of Earth is believed to be composed primarily of gases that were outgassed from the heated rocks sometime after the planet formed. This outgassing produced water vapor, carbon dioxide, nitrogen, and other gases that make up the Earth's atmosphere today.

Question 5

The speed of the solar wind is approximately 400 km/s and the distance from the Sun to Saturn is 9.5 AU (1 AU = $1.5 × 10^8$ km). How long does it take a particle in the solar wind to reach Saturn
A)about 4.1 hours
B)about 4.1 days
C)about 41 days
D)about 4.1 years
E)about 41 years

Accepted Answer

The distance from the Sun to Saturn is 9.5 AU, which is $9.5 \times 1.5 \times 10^8$ km. The speed of the solar wind is 400 km/s. Time taken is distance divided by speed, which gives approximately 41 days.

Question 6

Venus is often called Earth's sister planet because it is similar to the Earth in terms of
A)mass.
B)size.
C)density.
D)mass, size, and density.

Accepted Answer

Venus is often called Earth's sister planet because it is similar to Earth in terms of its mass, size, and density. Both planets are approximately the same size and have similar densities, which means they are both rocky planets. However, Venus has a much thicker atmosphere than Earth, and its surface temperatures are much hotter due to the greenhouse effect caused by its atmosphere's high concentrations of carbon dioxide.

Question 7

If the terrestrial planets were formed by homogeneous accretion, then
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

Homogeneous accretion suggests that terrestrial planets started as collections of solid particles. These particles then melted due to heat from impacts, radioactive decay, or gravitational compression, leading to differentiation based on density. This process resulted in the formation of a high-density iron metal core surrounded by a low-density silicate crust.

Question 8

The planets all lie in nearly the same plane resulting in a disk-like structure for the solar system. This disk-like structure is believed to exist because
A)the solar nebula from which the planets formed had a disk-like structure.
B)the bipolar flow from the young Sun cleared all material out of the nebula except that 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 widely accepted theory for the formation of the solar system is the nebular hypothesis, which suggests that the Sun and planets formed from a rotating disk of gas and dust called the solar nebula. This disk-like structure of the solar system is therefore believed to be a result of the original disk-like structure of the solar nebula from which it formed.

Question 9

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

Accepted Answer

Planetesimals are small, solid objects that formed during the early stages of the solar system's formation from the gas and dust in the solar nebula. Asteroids are small, rocky bodies orbiting the Sun that are believed to be fragments left over from the formation of the solar system, making them the best choice for objects most like planetesimals.

Question 10

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.
E)The one that has liquid water on its surface.

Accepted Answer

According to the solar nebula theory, the closer a planet is to the star, the hotter it will be during its formation, which would result in the volatilization of many materials that would greatly affect its density. Therefore, the planet closest to the star would be expected to have the greatest uncompressed density.

Question 11

Compared to the terrestrial planets, Jovian planets
A)have a higher density.
B)have a smaller number of moons.
C)have a much larger diameters.
D)are much hotter.

Accepted Answer

Jovian planets are much larger in diameter than terrestrial planets.

Answer: B 
 Jovian planets generally have a much larger number of moons than terrestrial planets.

Answer: A and D 
 None of the other options are correct, but Jovian planets typically have a lower density and are not hotter than terrestrial planets.

Question 12

Condensation in the solar nebula probably led to the formation of
A)icy grains beyond the present orbit of Jupiter.
B)metallic grains near the present orbit of Mercury.
C)silicate grains near the present orbit of Earth.
D)icy grains beyond the present orbit of Jupiter, metallic grains near the present orbit of Mercury, and silicate grains near the present orbit of Earth.
E)None of the other choices are correct.

Accepted Answer

Condensation in the solar nebula led to the formation of different types of grains at different distances from the forming Sun. The cooler temperatures beyond Jupiter allowed for the condensation of icy grains, while closer to the Sun metallic grains formed due to higher temperatures and silicate grains formed in between. Therefore, option D is correct as it includes all three types of grains formed in the solar nebula at different distances.

Question 13

The condensation sequence suggests that ____________ 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

The condensation sequence suggests that the substances with higher melting and boiling points will condense as solids closest to the Sun. Metals and metal oxides have higher melting points compared to silicates and ices of water, methane, and ammonia, and hydrogen and helium are gases at standard temperatures and pressures. Therefore, metals and metal oxides should condense as solids closest to the Sun as per the condensation sequence.

Question 14

The solar nebula theory is NOT able to explain which of the following observed characteristics of the solar system
A)common direction of rotation of the planets
B)common direction of revolution of the planets
C)the formation of hydrogen atoms in the solar system from subatomic particles
D)the density of the Jovian planets

Accepted Answer

The solar nebula theory is able to explain the common direction of rotation and revolution of the planets and the density of the Jovian planets, but it is not able to explain the formation of hydrogen atoms in the solar system from subatomic particles. This is due to the fact that the solar nebula theory only describes the physical processes occurring during the formation of the solar system, and not the chemical processes that produced hydrogen atoms.

Question 15

The diagram below 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)6.5 billion years
B)19.5 billion years
C)2.6 billion years
D)3.9 billion years
E)4.6 billion years

Accepted Answer

The answer of The diagram below illustrates the radioactive decay...

Question 16

Protoplanets of the Jovian planets could have grown very hot from
A)heat from the Sun.
B)radioactivity of light elements such as hydrogen and helium.
C)the infall of material at high velocity.
D)tidal forces due to the Sun.
E)collisions with large planetesimals.

Accepted Answer

The infall of material at high velocity during the formation of the protoplanets could have caused them to heat up. This is due to the conversion of gravitational potential energy into thermal energy, resulting in high temperatures.

Question 17

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 $3.3 × 10^{23}$ kg and a radius of 2439 km.
A)about 24 particles per second
B)about $3.3 × 10^{21}$ particles per second
C)about 67 particles per second
D)about 100 million particles per second
E)about 100 billion particles per second

Accepted Answer

The answer of Suppose that Mercury grew to its present...

Question 18

The large planetesimals would have grown faster than the smaller planetesimals because
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.
E)All of the other choices are correct.

Accepted Answer

The larger planetesimals would have had stronger gravity, and thus would have been able to pull in more material during the accretion process. This would have allowed them to grow faster than the smaller planetesimals. Choice A is incorrect because the speed of the planetesimal would not necessarily affect its growth rate. Choice C is partially correct, as there would have been more material available near the larger planetesimals, but this is not the only reason for their faster growth rate. Choice D is not a factor in the growth rate of planetesimals. Therefore, the best answer is B.

Question 19

The uncompressed density of a planet in our solar system
A)is greatest for the Jovian planets.
B)is greatest for the planets closest to the Sun.
C)is greatest for the planets furthest from the Sun.
D)is greatest for the planets with the largest mass.
E)is greatest of the planet with the largest radius.

Accepted Answer

The uncompressed density of a planet, which is a measure of its density without the effects of gravitational compression, is greatest for the terrestrial planets closest to the Sun (Mercury, Venus, Earth, Mars). These planets are composed primarily of rock and metal, which are denser materials compared to the gas and ice that make up the Jovian (gas giant) planets further from the Sun.

Question 20

The most important effect in clearing the solar nebula of gas and dust was
A)impacts by planetesimals.
B)the solar wind.
C)the Sun's magnetic field.
D)the asteroid belt.
E)radiation pressure.

Accepted Answer

Radiation pressure from the Sun's intense light and heat was the most important effect in clearing the solar nebula of gas and dust.

Quiz 15: The Origin of the Solar System

What observation made of other stars seems to suggest the solar nebula theory is correct

On a photograph of the 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

51 Pegasi is important because

Part of the current atmosphere of Earth is believed to be

The speed of the solar wind is approximately 400 km/s and the distance from the Sun to Saturn is 9.5 AU (1 AU = $1.5 × 10^8$ km) . How long does it take a particle in the solar wind to reach Saturn

Venus is often called Earth's sister planet because it is similar to the Earth in terms of

If the terrestrial planets were formed by homogeneous accretion, then

The planets all lie in nearly the same plane resulting in a disk-like structure for the solar system. This disk-like structure is believed to exist because

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

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

Compared to the terrestrial planets, Jovian planets

Condensation in the solar nebula probably led to the formation of

The condensation sequence suggests that ____________ should condense as solids closest to the Sun.

The solar nebula theory is NOT able to explain which of the following observed characteristics of the solar system

The diagram below 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

Protoplanets of the Jovian planets could have grown very hot from

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 $3.3 × 10^{23}$ kg and a radius of 2439 km.

The large planetesimals would have grown faster than the smaller planetesimals because

The uncompressed density of a planet in our solar system

The most important effect in clearing the solar nebula of gas and dust was