ASTRONOMY 101 - Test 3 (chapter 6)

Which of the following types of material can condense into what we call ice at low temperatures? - Rock - Metal - Hydrogen compounds - Hydrogen and helium

Hydrogen Compounds (Hydrogen compounds such as water, ammonia, and methane are gaseous at high temperature but condense into ice at low temperature)

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

The terrestrial planets in our solar system are _______

Mercury, Venus, Earth, and Mars

Which of the following is not a major pattern of motion in the solar system? - Nearly all comets orbit the Sun in same direction and roughly the same plane. - All of the planets orbit the Sun in the same direction - counterclockwise as viewed from above Earth's north pole. - Most of the solar system's large moons orbit in their planet's equatorial plane. - The Sun and most of the planets rotate in the same direction in which the planets orbit the Sun.

Nearly all comets orbit the Sun in same direction and roughly the same plane (This statement is untrue because comets of the Oort cloud, which are the most numerous of all comets, have randomly oriented orbits going in all directions around the Sun)

Which of the following is not one of the four major features of the solar system? - Several exceptions to the general trends stand out. - The solar system contains eight planets plus dwarf planets (including Ceres, Pluto, and Eris). - Large bodies in the solar system have orderly motions. - Planets fall into two major categories (terrestrial and Jovian). - Swarms of asteroids and comets populate the solar system.

The solar system contains eight planets plus dwarf planets (including Ceres, Pluto, and Eris).

T/F: It is considered part of our inner solar system

True

T/F: It is frozen today, but once had flowing water

True

T/F: Jovian planets are larger in mass than terrestrial planets

True

T/F: Jovian planets are larger in size than terrestrial planets

True

T/F: Jovian planets have more moons than terrestrial planets

True

T/F: Jovian planets orbit farther from the Sun than terrestrial planets

True

T/F: The Sun contains more than 98% of all the mass in our solar system

True

T/F: The Sun is a star

True

T/F: The Sun is made mostly of hydrogen and helium

True

T/F: We have landed spacecraft on its surface

True

Suppose you view the solar system from high above Earth's North Pole. Is the following statement true or false? All the planets orbit counterclockwise around the Sun

True (This is a consequence of the way the planets formed in a spinning disk around the young Sun)

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 (After 10 years, only half of the original kilogram will remain. After 20 years half of that half, or one-quarter of the original amount, will remain)

When we say that Jovian planets contain significant amounts of hydrogen compounds, we mean all the following chemicals except: - carbon dioxide - methane - water - ammonia

carbon dioxide (It contains only carbon and oxygen, it doesn't contain hydrogen)

Today, scientists have a theory (the nebular theory) that explains all the major characteristics of the solar system. In science, we expect a theory like this not only to explain the observed characteristics of our solar system but also to __________.

make testable predictions about other solar systems

What new process was added to our theory of planet formation to explain these surprising extra-solar planets?

migration

In essence, the Kepler mission is searching for extra-solar planets by _____

monitoring stars for slight dimming that might occur as unseen planets pass in front of them

If we can measure the period of a star's "wobble" caused by an orbiting planet, and if we also know the mass of the star, we can calculate the _______

size of the planet's orbit

Which of the following correctly describe patterns of motion in the solar system? - All the planets (not counting Pluto) have nearly circular orbits. - All the planets (not counting Pluto) orbit the Sun in nearly the same plane. - Inner planets orbit the Sun in the opposite direction from the outer planets. - The outer planets are so large that they nearly collide with each other on each orbit. - The inner planets all rotate in the same direction (west to east) as Earth. - Planets closer to the Sun move around their orbits at higher speed than planets farther from the Sun.

- All the planets (not counting Pluto) have nearly circular orbits. - All the planets (not counting Pluto) orbit the Sun in nearly the same plane. - Planets closer to the Sun move around their orbits at higher speed than planets farther from the Sun.

All the following statements are true. Which of them are considered to be "exceptions" to the general trends described by the first three major characteristics of the solar system? (choose all that apply) - Jupiter's largest moon, Ganymede, is even larger than Earth's moon. - Our Moon has a diameter more than 1/4 the diameter of Earth. - Uranus rotates with an axis tilt that lies nearly in the ecliptic plane. - Pluto is in the outer solar system but is ice-rich in composition. - Venus rotates in a direction opposite to the rotation of the other terrestrial planets

- Our Moon has a diameter more than 1/4 the diameter of Earth. - Uranus rotates with an axis tilt that lies nearly in the ecliptic plane. - Venus rotates in a direction opposite to the rotation of the other terrestrial planets

The solar system contains vast numbers of small bodies, which we call asteroids when they are rocky and comets when they are icy. These small bodies are concentrated in the region(s) of the solar system that we call __________. (choose all that apply) - the Oort cloud - the asteroid belt - the Kuiper belt - the solar corona - the Doppler belt - the comet belt

- the Oort cloud - the asteroid belt - the Kuiper belt

Suppose you find a rock that contains 10 micrograms of radioactive potassium-40, which has a half-life of 1.25 billion years. By measuring the amount of its decay product (argon-40) present in the rock, you conclude that there must have been 80 micrograms of potassium-40 when the rock solidified. How old is the rock?

3.75 billion years (The current 10 micrograms of potassium-40 is 1/8 of the original 80 grams, which means the amount of potassium-40 has declined by a factor of 8. Therefore, three half-lives have passed (since 23 = 8) and the rock is 3 × 1.25 = 3.75 billion years old)

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

4.5 billion years (This age has been well-verified by numerous independent measurements)

According to modern science, what was the approximate chemical composition of the solar nebula?

98% hydrogen and helium, 2% everything else (the sun still has this basic composition today)

According to our basic scenario of solar system formation, why do the jovian planets have numerous large moons?

As the growing jovian planets captured gas from the solar nebula, the gas formed swirling disks around them, and moons formed from condensation accretion within these disks.

In what way is Venus most similar to Earth?

Both planets are nearly the same size (This similarity in size means the two planets are probably similar in their interior structures and fundamental properties)

Suppose you view the solar system from high above Earth's North Pole. Is the following statement true or false? All the planets except Uranus orbit the Sun counterclockwise; Uranus orbits in the opposite direction

False

Suppose you view the solar system from high above Earth's North Pole. Is the following statement true or false? The inner planets orbit the Sun clockwise while the outer planets orbit the Sun counterclockwise

False

Suppose you view the solar system from high above Earth's North Pole. Is the following statement true or false? The inner planets orbit the Sun counterclockwise while the outer planets orbit the Sun clockwise

False

T/F: Jovian planets are higher in average density than terrestrial planets.

False

T/F: The Sun's diameter is about 5 times that of Earth

False (In fact, the Sun's diameter is more like 100 times that of Earth. That is, Earth is smaller than a typical sunspot)

T/F: We could survive on Mars without spacesuits, as long as we brought oxygen in scuba tanks

False (You would die quickly without a pressurized spacesuit, and you'd need protection from the cold and the ultraviolet radiation from the Sun)

According to our present theory of solar system formation, which of the following best explains why the solar nebula ended up with a disk shape as it collapsed? - The force of gravity pulled the material downward into a flat disk. - The law of conservation of energy. - It was fairly flat to begin with, and retained this flat shape as it collapsed. - It flattened as a natural consequence of collisions between particles in the nebula

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

According to our theory of solar system formation, what three major changes occurred in the solar nebula as it shrank in size?

It got hotter (consequence of conservation of energy), its rate of rotation increased (consequence of conservation of angular momentum), and it flattened into a disk (consequence of collisions between objects in a spinning system)

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 (Therefore planetesimals were built only of metal and rock within the frost line, but beyond the frost line they included ices along with metal and rock.)

Which are larger? Terrestrial or Jovian planets

Jovian

Does this statement apply to the formation of Terrestrial planets or Jovian planets? accreted from icy planetesimals

Jovian planets

Does this statement apply to the formation of Terrestrial planets or Jovian planets? ejected icy planetesimals that are now Oort cloud comets

Jovian planets

Does this statement apply to the formation of Terrestrial planets or Jovian planets? formed in a region of the solar system with lower orbital speeds

Jovian planets

Does this statement apply to the formation of Terrestrial planets or Jovian planets? formed in regions cold enough for water to freeze

Jovian planets

Does this statement apply to the formation of Terrestrial planets or Jovian planets? large moons formed in surrounding disks of material

Jovian planets

The Jovian planets in our solar system are _______

Jupiter, Saturn, Uranus, and Neptune

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

Leftover planetesimals that never accreted into planets (Asteroids are the rocky leftovers of the inner solar system and comets are the icy leftovers of the outer solar system)

How do scientists determine the age of the solar system?

Radiometric dating of meteorites

Does this statement apply to the formation of Terrestrial planets or Jovian planets? accreted from planetesimals of rock and metal

Terrestrial planets

Does this statement apply to the formation of Terrestrial planets or Jovian planets? surfaces dramatically altered during the heavy bombardment

Terrestrial planets

Which of the following is not a major difference between the terrestrial and Jovian planets in our solar system? - Terrestrial planets orbit much closer to the Sun than Jovian planets. - Jovian planets have rings and terrestrial planets do not. - Terrestrial planets contain large quantities of ice and Jovian planets do not. - Terrestrial planets are higher in average density than Jovian planets.

Terrestrial planets contain large quantities of ice and Jovian planets do not (Terrestrial planets actually contain very little ice, because they are made mostly of metal and rock.)

According to our present theory of solar system formation, which of the following statements about the growth of terrestrial and Jovian planets is not true? - The Jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal. - Swirling disks of gas, like the solar nebula in miniature, formed around the growing Jovian planets but not around the growing terrestrial planets. - Both types of planet begun with planetesimals growing through the process of accretion, but only the Jovian planets were able to capture hydrogen and helium gas from the solar nebula. - The terrestrial planets formed inside the frost line of the solar nebula and the Jovian planets formed beyond it.

The Jovian planets began from planetesimals made only of ice, while the terrestrial planets began from planetesimals made only of rock and metal. (The planetesimals in the outer solar system were not made only of ice: they also contained rock and metal. Remember, if it's cold enough for ices to condense from hydrogen compounds, it's certainly cold enough for rock and metal to condense as well)

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

The Moon formed from material blasted out of the Earth's mantle and crust by the impact of a Mars-size object (This is now considered the most likely explanation for the origin of our Moon)

Which of the following is not evidence supporting the idea that our Moon formed as a result of a giant impact? - The Moon's average density suggests it is made of rock much more like that of the Earth's outer layers than that of the Earth as a whole. - The Moon has a much smaller proportion of easily vaporized materials than Earth. - Computer simulations show that the Moon could really have formed in this way. - The Pacific Ocean appears to be a large crater - probably the one made by the giant impact.

The Pacific Ocean appears to be a large crater - probably the one made by the giant impact. (The Pacific Ocean is not an impact crater. Moreover, since the continents are rearranged with time, we can be sure that the giant impact occurred long, long before there was a Pacific Ocean)

The following statements are all true. Which one counts as an "exception to the rule" in being unusual for our solar system? - Saturn has no solid surface. - The diameter of Earth's Moon is about 1/4 that of Earth. - Venus does not have a moon. - Jupiter has a very small axis tilt

The diameter of Earth's Moon is about 1/4 that of Earth. (This makes the Moon surprisingly large compared to other planet/moon size differences in our solar system)

What do we mean by the period of heavy bombardment in the context of the history of our solar system?

The first few hundred million years after the planets formed, which is when most impact craters were formed (The heavy bombardment ended once most of the objects that could create impacts had either crashed into a planet or attained a stable orbit around the Sun)

What do we mean by accretion in the context of planet formation?

The growth of planetesimals from smaller solid particles that collided and stuck together (At first, accretion probably arose from electrostatic attractions, but as planetesimals grew larger their gravity allowed them to accrete more efficiently (as long as they didn't suffer collisions with similar-size planetesimals))

According to our theory of solar system formation, which law best explains why the solar nebula spun faster as it shrank in size? - The law of conservation of energy - Einstein's law E = mc^2 - The law of conservation of angular momentum - The law of universal gravitation

The law of conservation of angular momentum (To conserve angular momentum, the cloud particles had to move faster around the cloud center as their distance from the center decreased)

According to our theory of solar system formation, which law best explains why the central regions of the solar nebula got hotter as the nebula shrank in size? - The law of conservation of angular momentum - The two laws of thermal radiation - Newton's third law - The law of conservation of energy

The law of conservation of energy (As it shrank in size, gas particles lost gravitational potential energy. Since energy must be conserved, this energy became thermal energy)

Many meteorites appear to have formed very early in the solar system's history. How do these meteorites support our theory about how the terrestrial planets formed?

The meteorites appearance and composition is just what we'd expect if metal and rock condensed and accreted as our theory suggests (in other words, meteorites support our models of how accretion should have occurred)

Consider only the observed patterns of motion in the solar system. Scientifically, which of the following possible conclusions is justified from the patterns of motion alone? - The planets were not born within the past million years, but instead they must have been born billions of years ago. - The planets started out quite small and grew to their current sizes as they gradually accreted more material. - The planets were born from a giant cloud of gas that rotated in the same direction that the Milky Way Galaxy rotates. - The planets were not each born in a separate, random event.

The planets were not each born in a separate, random event.

What is the primary basis upon which we divide the ingredients of the solar nebula into four categories (hydrogen/helium; hydrogen compound; rock; metal)?

The temperatures at which various materials will condense from gaseous form to solid form

Why are terrestrial planets denser than Jovian planets?

The terrestrial planets formed in the inner solar nebula, where only dense materials could condense.

According to our present theory of solar system formation, how did Earth end up with enough water to make oceans?

The water was brought to the forming Earth by planetesimals that accreted beyond the orbit of Mars

About 2% of our solar nebula consisted of elements besides hydrogen and helium. However, the very first generation of star systems in the universe probably consisted only of hydrogen and helium. Which of the following statements is most likely to have been true about these first-generation star systems? - Like the jovian planets in our solar system, the jovian planets in these first-generation systems were orbited by rings. - There were no comets or asteroids in these first-generation star systems. - These first-generation star systems typically had several terrestrial planets in addition to jovian planets. - Jovian planets in these first-generation star systems had clouds made of water and other hydrogen compounds.

There were no comets or asteroids in these first-generation star systems.

What was so surprising about the first extra-solar planets that they forced a change in our theory of planet formation?

They were massive like Jupiter, but very close to their host star.

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 (why we say that we and our planet are made from "star stuff.")

Which planet listed below has the most extreme seasons? - Earth - Uranus - Mars - Jupiter

Uranus (seasons are caused primarily by axis tilt. Uranus essentially rotates on its side compared to its orbit, giving it very extreme seasons)

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

Venus, its extreme temperature is caused by its very strong greenhouse effect

According to our present theory of solar system formation, list the major ingredients of the solar nebula in order from the most abundant to the least abundant

hydrogen and helium gas; hydrogen compounds; rock; metal

Compared to the distance between Earth and Mars, the distance between Jupiter and Saturn is _________

much larger

In essence, the nebular theory holds that __________

our solar system formed from the collapse of an interstellar cloud of gas and dust (this cloud of gas is called the solar nebula)

If we can measure the period of a star's "wobble" caused by an orbiting planet, we know the _______

period of the planet's orbit

Now consider why the observed patterns of motion lead to the conclusion that the planets were not born in separate, random events. The reason for this conclusion is that, if the planets had been born in separate, random events, we would expect that __________.

planetary orbits would have many different orientations and directions, rather than all being in the same direction and in the same plane

How is Einstein's famous equation, E = mc^2, important in understanding the Sun?

the Sun generates energy to shine by losing 4 million tons of mass each second

Complete this statement. The larger the decrease in the star's brightness as the planet transits in front of a star, _______

the larger the size of the planet