Astronomy Midterm

(a) Which is not true about the greenhouse effect? (b) What is not true about global warming?

? (not It is the natural heating mechanism of Earth's atmosphere) It is just another name for the greenhouse effect.

According to Kepler's third law, there is a relationship between the time a planet takes to revolve around the Sun and its _____.

? (not eccentricity)

Based on what you know about telescopes located in space, select all of the correct statements from the following list.

??

What evidence would you expect to find on the Moon if it had been subjected to plate tectonics? (Select all that apply.) Do you find such evidence?

?? No

You are sitting next to a person who has twice as much weight. You get up and move one seat over, doubling your distance from them. Did the gravitational force between you increase, decrease, or stay the same?

Gravitational force decreased.

Why did Copernicus have to keep small epicycles in his models? Which planet has the longest duration of retrograde motion as viewed from Earth? Which planet has the shortest duration of retrograde motion as viewed from Earth?

His model did not predict planetary positions as well as the Ptolemaic system. Neptune Mars

The scientist who formulated the three laws of planetary motion by analyzing the data on the precise location of planets in the sky was _____.

Johannes Kepler

A planet in our solar system whose composition resembles that of our Sun is _____.

Jupiter

Which of the following is NOT a terrestrial planet?

Jupiter

The planet closest to the Sun in the solar system is _____.

Mercury

What happened to the majority of the carbon dioxide that was formerly in Earth's atmosphere?

Most of it dissolved into the oceans and now is in the form of limestone rocks of Earth's crust.

(a) How was the Hawaiian-Emperor island chain formed? (b) How does the formation of the Hawaiian-Emperor island chain help in the understanding of tectonics?

Motion of the Pacific plate allowed volcanic hot-spots to punch through the crust. It is an example of tectonics and volcanism working together to form mountains.

What is, by far, the most abundant component of Earth's atmosphere?

N2

The first human being to step out onto the surface of another world was _____.

Neil Armstrong

Why did Newton conclude that gravity has to be mutual and universal?

Newton's third law stated that for every action there is an equal and opposite reaction, so he concluded gravity must be mutual. He reasoned that the Sun, the planets, and all their moons must also attract each other by mutual gravitation, so he concluded that gravity must be universal.

(a) According the solar nebula hypothesis, which of the following is true? (b) What is the reason for the answer to the previous question? (c) Is there any evidence to support the answers to the previous questions?

Planetary systems should be common. According to the theory, planets form from the gases surrounding a star after it forms. Yes; disks of gas and dust and actual planets have been discovered orbiting other stars.

Why does the amount of blackbody radiation emitted depend on the temperature of the object?

The temperature of a heated object determines how fast the particles vibrate or move within that material. Objects with large temperature have particles that are moving very -rapidly-. Particles that are moving -rapidly- will run into each other much more often than particles that are moving -slower- and on average will release -more- energy in each collision. Therefore, hot objects should radiate -more- energy than cooler objects.

What is the difference between speed and velocity?

The velocity of an object indicates both the object's speed (rate of motion) and its direction of motion.

Why do hot stars look bluer than cool stars?

The wavelength that a star radiates the most energy is inversely proportional to the temperature.

Which of the following ways that jovian (giant) planets differ from the terrestrial planets is NOT CORRECT?

jovians (being larger) rotate significantly more slowly than terrestrials

(a) Rank each atmospheric composition in order of when it occurred on Earth, oldest first: carbon dioxide, and oxygen. (b) Rank the following atmospheric gases in order of their abundance in Earth's current atmosphere: carbon dioxide, nitrogen, oxygen.

oldest: carbon dioxide youngest: oxygen most: nitrogen oxygen carbon dioxide least:

Which of the following statements about our Moon is FALSE?

on Earth, we can see all its sides in the course of a month as it goes around us

How fast do electro-magnetic waves travel?

at the speed of light

The most important function of an astronomical telescope is to _____.

collect as much light as possible and bring it to a focus

A new technique called adaptive optics allows astronomers to _____.

compensate for changes in the Earth's atmosphere and achieve better resolution

Atoms typically consist of electrons, protons, and neutrons. The most common isotope of one element, however, only has two of these three types of particles. This element is _____.

hydrogen

Which of the following has the highest frequency?

gamma rays

Where in an atom would you expect to find electrons? Where in an atom would you expect to find protons? Where in an atom would you expect to find neutrons?

in an orbit around the nucleus within the nucleus within the nucleus

Frozen water exists on the lunar surface primarily in which location? Why?

in craters near the poles Because sunlight doesn't reach those areas as well so they stay frozen there.

If the frequency of an electromagnetic wave increases, does the number of wave peaks passing by you increase, decrease, or stay the same? Does the wavelength increase, decrease, or stay the same? Does the energy of the photon increase, decrease, or stay the same?

increase decrease increase

When an atom has lost one or more electrons, it is said to be _____.

ionized

The inner planets are made mostly of rock and metal because _____.

it was so hot where the inner planets formed that the lighter materials evaporated

The material that would eventually make all the major bodies in our solar system first gathered together as smaller pieces which astronomers call _____.

planetesimals

What produced the oxygen in Earth's atmosphere?

plants

In this figure you can see that different wavelengths of light are refracted (bent) by different amounts. Which wavelengths are bent by the greatest amount?

short wavelengths

Explain how each of Galileo's telescopic discoveries contradicted the Ptolemaic theory. Surface features on the Moon: Stars that are too faint to be seen with the naked eye: The moons of Jupiter: Sunspots: The phases of Venus:

showed that a heavenly body could be imperfect does not support or contradict the Ptolemaic theory showed that a heavenly body could have satellites ? Showed that the orbits of planets are elliptical showed that a planet orbited the Sun

When the Sun and Moon are lined up and pull together, the tides they raise are called _____.

spring tides

Wien's Law relates the wavelength at which a star gives off the greatest amount of energy to the star's _____.

temperature

(a) Which planets are more dense? (b) Based on the solar nebula theory, what is the reason for the observation in the previous question?

terrestrial planets Both of the above are true. - Terrestrial planets formed from solid material that condensed out of the solar nebula close to the sun, where it was too hot for them to capture gases. - Jovian planets started out with solid material as well, and were far enough from the sun for a layer of ice to form, after which they became massive enough to capture slower-moving gases.

Why does the Moon show phases in the course of a month?

the angle the Moon makes with the Sun changes and we see differing amounts of reflected sunlight

Which of the following descriptions is a definition of an astronomical unit (AU)?

the average distance between Earth and the sun

When a knowledgeable amateur astronomer tells you that she has a 14-inch telescope, what does the number 14 refer to?

the diameter of the primary lens or mirror

The ground state in an atom is _____.

the electron orbit with the lowest possible amount of energy

The seven days of the week are named after _____.

the seven "wandering" objects in the Sky that were visible to the ancients

Our best evidence and theoretical calculations indicate that the solar system began with a giant spinning system of gas and dust that scientists call _____.

the solar nebula

Which of the following characteristics do all four terrestrial planets have in common?

they all have solid surfaces with signs of geological activity on them

What is one important way in which both the Moon and Mercury are different from Earth?

they do not have an atmosphere

The light which allows you to see this very interesting exam is made up of waves. In these waves, the distance between crests is called the

wavelength

Which of the following is the Earth NOT located in?

we are located in all of the above - the Local Group of galaxies - the Milky Way Galaxy - the solar system - The Virgo supercluster

What is the most important reason that astronomers have learned more about our planetary system in the last 30-40 years than all of history before then?

we have been able to send spacecraft to gather information about planets and moons up close

Astronomers observe a typical star using a telescope and a spectrometer. They will see _____.

more than one of the above - an absorption spectrum - a continuous spectrum - an emission spectrum - a Doppler shift

(a) Where in the solar system are asteroids found? (b) How does the solar nebula theory help you understand the location of asteroids?

mostly in the belt between Mars and Jupiter, but in other orbits as well Both of the above are true. - Many of the asteroids are material that would have formed a terrestrial planet, but could not, due to gravitational pull from Jupiter. - Asteroids in places other than the belt are debris left over from the formation of the solar system.

When a planet, in its orbit, is closer to the Sun, it _____.

moves faster than average

What phase of the Moon must it be to have a solar eclipse?

new moon

Which of the following statements about the nucleus of a typical atom (such as a carbon atom in your little finger) is FALSE?

the nucleus repels the electrons which move around it

Which of the following statements about electromagnetic radiation is FALSE?

the radiation consists of tiny charged particles given off by the nuclei of atoms

The period of the moon's rotation on its axis is _____.

the same as its revolution around the Earth

(a) What must be true about Earth's core to generate Earth's magnetic field? (b) Which of these conducting materials is not found in the Earth's core? (c) What must be true for a large portion of Earth's core in order for convection to occur?

All of the above must be true. - The material must be conductive. - The core must be rotating. - The material must convecting. copper It must be liquid.

What creates Earth's strong dipole magnetic field?

Convection in Earth's outer liquid iron-nickel core combined with Earth's rotation.

The Earth is closest to the Sun in which month of the year?

January

Where on Earth are two plates being pushed apart and new crust created?

along the center of the Atlantic Ocean and along the center of the Red Sea

The smaller objects in the solar system made of rock and metal (most of which orbit between Jupiter and Mars) are called _____.

asteroids

You have learned how astronomers talk about huge astronomical distances. Based on what you learned, select all of the correct statements from the following list.

- The distances to stars are measured in light years. - A light-year is larger than an astronomical unit. - Astronomers use the metric system for calculations.

What are Earth's core and mantle made of? (Select all that apply.) Explain how we know. (Select all that apply.)

- The mantle is made of rock. - The core is primarily made of iron and nickel. - using our understanding of planetary formation and internal differentiation - through chemical analysis of samples from material ejected from volcanoes - analyzing seismic waves through the Earth's interior

You have learned about the relative sizes of objects and the distances between them. Based on what you learned, select all of the correct statements from the following list.

- The solar system is part of our galaxy. - Earth is about 4 times the diameter of the moon. - Our galaxy is thousands of light-years across. - The sun is about 100 times the diameter of Earth.

Describe two ways an atom can become excited. (Select all that apply.)

- absorption of a photon - collisions

Summarize the four main hypotheses for the origin of the Moon.

- A large object collided with Earth and ejected a large amount of Earth's mass into space, which became the Moon. - The Moon formed elsewhere in the solar system and was captured by Earth. - The Moon and the Earth formed at the same time, but separately. - The Moon was once part of the Earth, but they separated early in their history.

The moon goes through a cycle of phases. This occurs because as the moon orbits Earth, differing parts of the side of the moon illuminated by the sun face toward Earth. Based on what you know about this cycle of phases, select all of the correct statements from the following list.

- During the new phase, no direct sunlight reaches the side of the moon facing Earth. - Quarter phases occur between the new and full phases. - Since a full moon occurs when the moon is on the opposite side of Earth as the sun, it is only visible at night.

Based on what you know about Newton and gravity, select all of the correct statements from the following list.

- Forces always occur in pairs. - A change in motion is called acceleration. - Changes in motion require force.

You have learned where Earth is in relation to the sun, other planets and galaxies. Based on what you learned, select all of the correct statements from the following list.

- Galaxies are composed of billions of stars. - The sun is a star. - The Milky Way is a spiral galaxy. - Earth and most of the other planets orbit the sun in nearly circular elliptical orbits.

Based on what you know about how astronomers use radio telescopes, select all of the correct statements from the following list.

- Radio waves can travel through obstacles that block out waves of visible light. - Radio telescopes have to be larger than optical telescopes, since radio waves are longer than visible light waves.

According to the solar nebula theory, why is Earth's orbit nearly in the plane of the Sun's equator?

As gas particles orbited the Sun, collisions caused the particles to settle in a disk at roughly a right angle to the Sun's rotation axis.

Why does the Moon not have an atmosphere?

Because the Moon's mass is so small, its gravity cannot prevent gas molecules from quickly escaping into space.

How does the large-impact hypothesis explain the moon's lack of iron?

Both planetesimals were differentiated, and the two iron cores went to Earth.

Why do different atoms have different lines in their spectra?

Different atoms have different lines in their spectra because different elements have different energy levels for the -electrons- . The total number of protons, neutrons, and electrons that the individual atom contains determines the -electrons- energy levels; therefore, the number of protons, neutrons, and electrons determines where the energy levels are to be for the atoms and these energy levels control the energies of the transitions that can occur.

Which of the following statements about eclipses of the Sun is true?

For a total eclipse of the Sun to happen, the Moon must get directly in front of the Sun, as seen from Earth

Why is an absorption spectrum especially useful for astronomers?

It has dark lines in it that allow astronomers to determine what elements are in the star

(a) What did Plato propose about all heavenly motion? (b) Why did Plato propose what he did about heavenly motion and the shape of heavenly objects? (c) What effect did Plato's proposal have on future astronomers?

It is in circular paths. because he believed the sphere to be the most perfect geometrical form His idea od a sphere being the most perfect geometric form influenced astronomical theories for literally hundreds of years.

What is the likely source of Earth's early atmosphere that consisted of carbon dioxide and water vapor?

It was outgassed from Earth's interior during volcanic activity and it arrived in the form of icy planetesimals that impacted Earth.

How does Kepler's first law of planetary motion overthrow one of the basic beliefs of classical astronomy? How about Kepler's second law?

Kepler's first law says that the orbits of the planets are ellipses, rather than perfect circles or series of epicycles. Kepler's second law says that the planets speed up and slow down during their orbits, rather than remain in uniform motion.

Why do solar eclipses happen only at new moon? Why not every new moon?

Since the shadow of the Moon extends directly away from the Sun, a solar eclipse can occur only when the Moon is between the Earth and the Sun. Solar eclipses don't occur every new moon because of the Moon's orbital tilt.

Briefly describe the greenhouse effect.

Sunlight is absorbed by Earth's surface then reemitted as infrared radiation. Greenhouse gasses absorb this radiation, resulting in a higher surface temperature for the planet.

How can the Doppler effect explain wavelength shifts in both light and sound?

The Doppler effect is produced when the source and observer of a wave are moving relative to each other, regardless of the type of waves produced.

In Ptolemy's model, how do the epicycles of Mercury and Venus differ from those of Mars, Jupiter, and Saturn?

The epicycles of Mercury and Venus were attached to a line joining Earth and the Sun. The epicycles of Mars, Jupiter, and Saturn revolved around Earth independently of the Sun.

What distinguishes Earth's inner core from its outer core?

The inner core is solid, and the outer core is liquid.

Why does the same side of the moon always face Earth?

The moon rotates in the same direction that it revolves and the moon's period of rotation is equal to its orbital period.

Explain how we can deduce the temperature of a star by determining its color.

The peak wavelength of a blackbody spectrum, which is the color, is inversely proportional to its temperature.

Why are near-infrared telescopes located on mountaintops and ultraviolet telescopes in Earth orbit?

The primary infrared blocker, water vapor, is mostly in the lower atmosphere and the primary ultraviolet blocker, ozone, is located high in the atmosphere, far above mountaintops.

The 17th century astronomer who kept a roughly 20 year continuous record of the positions of the Sun, Moon, and planets was _____.

Tycho Brahe

Why can't the Moon be eclipsed when it is halfway between the nodes of its orbit?

When the Moon is halfway between the nodes, it would be approximately 5 degrees above or below the ecliptic, and hence, could not be directly opposite the Sun.

A car is on a circular off ramp of an interstate and is traveling at exactly 25 mph around the curve. Does the car have velocity? Does the car have acceleration? Is the car decelerating?

Yes Yes No

Does Tycho's model of the Universe explain the phases of Venus that Galileo observed? Why or why not?

Yes. In Tycho's model all planets except Earth orbit the Sun, and the Sun orbits Earth once each day. In this model Venus shows a full set of phases.

Which statement below best describes the difference between your mass and your weight?

Your mass is a measure of the amount of matter that you contain and your weight is a measure of the amount of gravitational pull that you experience.

Newton showed that to change the direction in which an object is moving, one needs to apply _____.

a force

Which of the following is not an advantage that a reflector telescope has over a refractor telescope?

a reflector doesn't have to deal with the twinkling of the stars, as a refractor does

From a particular location on Earth, why can we see many more total eclipses of the Moon than total eclipses of the Sun?

a total lunar eclipse is visible over a much larger part of the Earth's surface than a total solar eclipse

To go from a lower level in an atom to a higher level, an electron must _____.

absorb a photon of energy

In what ways is Earth unique among the Terrestrial worlds?

all of the above - oceans - a nitrogen-oxygen atmosphere - life

Which of the following is due to the moon's small size?

all of the below - The moon has no atmosphere. - The moon does not have a dipole magnetic field. - The moon does not have plate tectonics. - The moon's surface geology is dominated by impact craters.

In the future, several students living on board a space station decide to have a race among different types of electromagnetic radiation. Which of the following travels through space the fastest?

all of these travel through space at the same speed - visible light - infrared - x-rays - radio waves

An artist who likes working with sources of light decides to make a modern sculpture out of electrified glass tubes that contain very thin (rarified) neon gas. When the sculpture is finished, and the electricity is turned on, the tubes glow with a rich red color. What we are seeing is _____.

an emission spectrum

What kind of spectrum does a neon sign produce? Describe this process. What colors are associated with a neon sign?

an emission spectrum An emission spectrum occurs when low-density gases emit light at specific wavelengths and the light excites the electrons in the atoms. The color produced has to do with the gas not being so dense.

The average temperature on planet Earth is higher than you would expect just from the heating of sunlight alone. What is the explanation for this?

carbon dioxide (and other gases) in the atmosphere cause a greenhouse effect

The way scientists know that a hypothesis in astronomy is a reasonable description of nature is to _____.

do experiments and observations about the predictions of the hypothesis

By the term universe, astronomers mean _____.

everything that we can observe

Two versions of an element with different numbers of neutrons are called _____.

isotopes

We have two waves of light, A and B. Wave A has a higher frequency than wave B. Then wave B must have _____.

longer wavelength

An astronomer discovers a new star and wants to measure its temperature. She would typically do this by _____.

making a blackbody curve and finding the wavelength of the peak (maximum)

(a) Mercury's core is probably which of the following? (b) What evidence do astronomers have for the answer to the previous question? (c) Mercury's core is probably which of the following? (d) What evidence do astronomers have for the answer to the previous question?

partially molten a weak magnetic field metallic Mercury is small and of high density.

Not all wavelengths of electromagnetic radiation can penetrate the Earth's atmosphere. Of the following types of waves that come from space, which one are you likely to be able to detect most easily from our planet's surface?

radio waves of the wavelength that carry FM broadcasts

All the planets (without exception) _____.

revolve around the Sun in the same direction

Which theory of the Moon's origin do astronomers (and the evidence) favor?

the giant impact theory

A single star in the process of forming starts by spinning slowly (while it is quite large and relatively cool.) As the star collapses under the pull of its own gravity, its size decreases. As a result, its rate of spinning _____.

will increase