Astronomy 101 Thought Questions - Fall 2007

Thought Questions for Astronomy 101 (Fall 2007)
Instructor: Eric Sandquist


Animations about Color

Animations about Blackbody Radiation

Concept Map about Earth's Atmosphere

Concept Map about Venus' Atmosphere

Thought Questions from first Midterm


Thought Questions for Midterm #2:

Question Topics:

Light
Atoms
Planet Atmospheres
Blackbody Radiation
Jovian Planets
Types of Spectrum
Terrestial Planet Geology
Formation of the Solar System

Light

Which size of tuning fork will produce the highest pitch (frequency) sound?

  1. The longest tuning fork.
  2. A middle-sized tuning fork.
  3. The shortest tuning fork.
  4. They will all produce sound of the same pitch.
Answer: 3. Hint: There is a relationship between the frequency of a wave and its wavelength, and sound is a kind of wave. High frequency means small wavelength, and small musical instruments can only create short wavelengths of sound.

What is the meaning of the pictured experiment?

  1. Prisms create new colors from white light.
  2. Prisms add new colors to white light.
  3. White light is a mixture of light with different colors.
  4. Yellow light is a mixture of light with different colors.
Answer: 3. Hint: The yellow light passing through the second prism does not become a second rainbow.

If the light hitting the prism goes through a red filter first, what will you end up seeing on the screen?

  1. The light that passes through the prism will be white.
  2. The light that passes through the prism will be red.
  3. The light that passes through the prism will be everything except red.
  4. No light will pass through the prism.
Answer: 2. Hint: The red filter blocks (or absorbs) all of the colors in the white light except for the red.

A person's clothes appear dark blue when the fluorescent lights (white light) are on. How will the person's clothes appear when the street lamp (which emits pure yellow light) is on?

  1. The clothes will appear blue.
  2. The clothes will appear green.
  3. The clothes will appear black.
  4. The clothes will appear yellow.
Answer: 3. Hint: If there is no blue light hitting the blue clothes, then none of the light will be reflected, and the clothes will apear black.

A person's clothes appear dark red when the fluorescent lights (white light) are on. How will the person's clothes appear when the street lamp (which emits pure yellow light) is on?

  1. The clothes will appear red.
  2. The clothes will appear orange.
  3. The clothes will appear black.
  4. The clothes will appear yellow.
Answer: 3. Hint: If there is no red light hitting the red clothes, then none of the light will be reflected, and the clothes will appear black.

If you look at a blue dot on the screen through a red filter, what will you see?

  1. A blue dot.
  2. A red dot.
  3. A black dot.
  4. A white dot.
Answer: 3. Hint: Only blue light is coming from the dot on the screen. However, the red filter only lets red light through, so no light gets through and it will appear black.

If you look at a red dot on the screen through a blue filter, what will you see?

  1. A blue dot.
  2. A red dot.
  3. A black dot.
  4. A white dot.
Answer: 3. Hint: Only red light is coming from the dot on the screen. However, the blue filter only lets blue light through, so no light gets through and it will appear black.

Compared to other colors of visible light, red light has

  1. higher energy and longer wavelength.
  2. lower energy and longer wavelength.
  3. lower energy and shorter wavelength.
  4. higher energy and shorter wavelength.
Answer: 2. Hint: Remember that red light has the longest wavelength of any kind of visible light. The energy is related to wavelength - longer wavelength means lower energy.

If you removed the green and orange light coming from an object that is releasing the mixture below, what would the spectrum look like?

Answer: A. Hint: Green and orange are kinds of light on their own.

Which of the following spectrums represents the light from red and blue TV dots?

Answer: D. Hint: A red dot on your TV screen don't exclusively release red light, but it does mostly release light near red in wavelength.

Which of the following is true?

  1. Radio photons have a longer wavelength than optical photons.
  2. X-ray photons have a larger frequency than optical photons.
  3. Infrared photons have a smaller energy than optical photons.
  4. All of the above.
  5. None of the above.
Answer: 4. Hint: How do energy, wavelength, and frequency relate to each other?


Blackbody Radiation

If you watch the light bulb with only your eyes, what is going to happen to the light bulb filament as I increase its temperature?

  1. The filament will start out dark, then become faint and reddish, then become bright and white.
  2. The filament will start out dark, then become faint and white, then become bright and white.
  3. The filament will start out dark, then become faint and white, then become bright and red.
Answer: 1. Hint: The light bulb filament is a blackbody. As the temperature increases, both the color and brightness of the filament change. REMEMBER: "red hot" is NOT hotter than "white hot"!!!

At a particular temperature, the light bulb appears orangish in color if you look at it with only your eye. What color has to be added in large amounts to get it to appear whiter?

  1. red
  2. orange
  3. blue
Answer: 3. Hint: "White light" is a roughly equal mixture of all of the colors of the rainbow. If the filament appears orange, there is more red, orange, and yellow than there is green and blue.

As I increase the temperature of the light bulb filament, one student watches the the color blue in the rainbow, while another student watches the color red. What will the two students see?

  1. Both colors get brighter.
  2. The color blue gets brighter, but the color red gets fainter.
  3. The color red gets brighter, but the color blue gets fainter.
  4. Both colors get fainter.
Answer: 1. Hint: Photons of light are released during every collision between atoms in the filament. The higher the temperature, the more collisions occur. Every collision results in a release of light.

Which color will become visible last as the temperature of the light bulb filament is increased?

  1. red
  2. orange
  3. yellow
  4. green
  5. blue
  6. violet
Answer: 6. Hint: As the temperature increases, collisions become more violent (and more energetic) because the atoms are travelling faster. Photons with a lot of energy can only be created during the violent collisions.

Police are following a suspect at night in San Diego using an infrared camera. If the suspect jumps into the harbor, what will be seen on the camera?

  1. The suspect is dark, but becomes bright after jumping in.
  2. The suspect is dark, even after jumping in the water.
  3. The suspect is bright, even after jumping in the water.
  4. The suspect is bright, but becomes dark after jumping in.
Answer: 4. Hint: Normally humans release a lot of infrared light because of their temperatures. When the suspect jumps in the cold San Diego water, his skin immediately cools off and makes him "dim".

Using the graph below, which of the following best describes how star A compares to star B?

  1. Star A gives off more red light than star B.
  2. Both stars give off the same amount of red light.
  3. Star B gives off more red light than star A.
  4. None of the above.
Answer: 1. Hint: Find the wavelength with the color red. Notice that the curve for star A falls higher than the cure for star B, meaning star A releases more red light. Just because red is the brightest color for star B DOES NOT mean that it must be the brightest star in red light!

The graph below shows the blackbody spectra for three different stars. Which of the stars has the reddest peak wavelength?

  1. Star A.
  2. Star B.
  3. Star C.
Answer: 3. Hint: By "reddest peak wavelength", we mean the one that has the peak with the largest wavelength (most to the right).

The graph below shows the blackbody spectra for three different stars. Which of the stars has the highest temperature?

  1. Star A.
  2. Star B.
  3. Star C.
Answer: 1. Hint: Hot objects have short peak wavelength (most to the left), which makes them appear to have a bluer tint.

In the graph below, which of the statements best describes how star A appears in comparison to star B?

  1. Star A looks redder than star B.
  2. Both stars look reddish.
  3. Both stars look bluish.
  4. Star A looks redder than star B.
  5. None of the above.
Answer: 4. Hint: Star A is releasing much more blue light than red light, which makes it appear blue. Star B is the opposite - it will appear reddish.

Stars A and C sit at the same distance from you. According to the graph below, which of these statements is true?

  1. Star A is smaller than star C.
  2. Star A is larger than star C.
  3. The stars have the same size.
  4. It is impossible to tell from this graph.
Answer: 2. Hint: Both stars are the same temperature (their peaks are at the same wavelength), but star A is brighter. Star A must be larger (more surface to release light).

The Sun appears to have a yellow-white color to our naked eyes. If you were to look at another star that was hotter than the Sun, which of the following tints could it be?

  1. red
  2. yellow
  3. yellow-white
  4. blue-white
Answer: 4. Hint: As the temperature increases, what colors become most intense?

Two stars have the same size, but different surface temperatures: one has a temperature equal to that of the Sun (about 5800 degrees Kelvin), while the other has a temperature twice that. Which of the following is NOT true?

  1. The hotter star is brighter than the cooler star.
  2. The hotter star emits more blue light than the cooler star.
  3. The hotter star emits more red light than the cooler star.
  4. The most intense light from the hotter star has a longer wavelength than the most intense light from the cool star.
Answer: 4. Hint: A blackbody gets brighter as its temperature increases, and it emits more light at all wavelengths. However, the color of the most intense light becomes bluer (shorter wavelength).


Types of Spectrum

I have a jug of clear blue liquid. Which of the following is true?

  1. The liquid is not doing anything to the light that hits it.
  2. Most of the violet, blue, and green light is bouncing off the liquid and coming to your eyes.
  3. Most of the yellow, orange, and red light is bouncing off the liquid and coming to your eyes.
Answer: 2. Hint: The jug is not hot, so it is not emitting visible light. The fact that you see it is blue means that blue light (and similar colors) is reaching your eyes.

When I pass the jug of clear blue liquid in front of the light bulb, what will you see in the spectrum?

  1. The jug will make the violet, blue and green light more intense.
  2. The jug will make the yellow, orange, and red light more intense.
  3. The jug will remove most of the violet, blue, and green light.
  4. The jug will remove most of the yellow, orange and red light.
Answer: 4. Hint: The jug is not hot, so it is not emitting visible light. It is transparent. The fact that you see it is blue means that blue light is reaching your eyes. So in this case, some of the orange and yellow light is likely to be removed from the mixture of light coming from the light bulb.

Which of the following patterns most closely correponds to the pattern of lines you saw in the spectrum in class?

Answer: D. Hint: I include this question just to remind you that the pattern of lines can be used to uniquely identify the chemical creating the lines. (This spectrum was for hydrogen gas.)

Imagine that you are on the surface of Earth (below the atmosphere) and are observing the Sun. What kind of spectrum would you observe by analyzing the sunlight?

  1. a continuous spectrum
  2. an emission line spectrum
  3. an absorption line spectrum
Answer: 3. Hint: Light from a hot opaque object (the Sun) is passing through a cool gas (Earth's atmosphere). This is Kirchoff's third law.

Imagine that you are on looking at two different spectra of the Sun. Spectrum number #1 is obtained using a telescope in orbit high above Earth's atmosphere. Spectrum #2 is obtained using a telescope on Earth. Which spectrum comes from the telescope on Earth (#2)?

Answer: Bottom. Hint: Earth's atmosphere absorbs some of the sunlight passing through it, adding new lines to the spectrum.

Imagine that white light is falling on your red shirt. If you took a spectrum of the light reflecting off your shirt, what would you see?

  1. Red would be one of the brightest colors.
  2. Red would be one of the darkest colors.
  3. Red would be completely removed from the spectrum.
Answer: 1. Hint: The red you see is light reflected from the clothes. Other colors (like blue) would be absorbed by the chemical dyes in the shirt.


Atoms

Why do electrons move around the nucleus of the atom?

  1. There is no force on the electrons.
  2. A force must be continuously changing the direction each electron is moving in.
  3. There are two equal and opposite forces acting on each electron.
Answer: 2. Hint: Just like a satellite in orbit, there must be a net acting on the electron to have it move in a curved path (Newton's first law of motion).

The electrical force attracts an electron to a proton. To move an electron from a low orbit to a high orbit (farther from the proton), what has to happen?

  1. Energy has to be absorbed.
  2. Energy has to be released.
  3. Nothing has to happen - the electron will change orbits on its own.
Answer: 1. Hint: The electrical force attracts the electron to the nucleus and holds it in its orbit, so effort has to be spent to move the electron away.

A green photon must be absorbed to get an electron to move from the ground state to an excited state (a larger orbit). To get the electron to move to a higher excited state (an even larger orbit), what kind of photon might the electron be able to absorb?

  1. green
  2. red
  3. blue
Answer: 3. Hint: The farther the electron is moved away from the nucleus, the more energy is needed. Blue photons have more energy that red or green photons.

An atom has energy levels with energies of 0, 3, and 5 units. The energy level with an energy of 5 units is the outermost boundary of the atom. Assuming this atom has a single electron in the ``0'' energy level (the ground state), which of the following photon energies can the electron absorb to move it to another orbit?

  1. 3 units only.
  2. 3 units or 2 units.
  3. 3 units or 5 units.
  4. 3 units or 8 units.
  5. 5 units only.
  6. 8 units only.
Answer: 3. Hint: Absorbing 3 units of energy would get the electron to first excited state from the ground state. Absorbing 5 units get the electron to the second excited state from the ground state.

An atom has energy levels with energies of 0, 3, 9, and 10 units. The energy level with an energy of 10 units is the outermost boundary of the atom. Assuming this atom has a single electron in the ``3'' energy level, which of the following photon energies can the electron absorb? (There are two correct answers.)

  1. 1 unit.
  2. 3 units.
  3. 6 units.
  4. 8 units.
Answer: 3 or 4. Hint: Absorbing 6 units of energy would get the electron to the energy level having an energy of 9 units. Aborbing 8 units would give the electron enough energy to get past the energy level having 10 units, which means the electron could be removed ("ionization").

Atom X has energy levels with energies of 0 and 10 units. Atom Y has energy levels with energies of 0 and 12 units. In each atom, an electron moves from the upper energy level to the lower energy level, emitting a single photon in the process. Which of the photons has longer wavelength?

  1. The photon from atom X.
  2. The photon from atom Y.
  3. The photons will have the same wavelength.
Answer: 1. Hint: A photon of long wavelength has relatively little energy.


Terrestrial Planet Geology

Mountain ranges form where plates are
  1. pushing against each other
  2. pulling apart.
  3. sliding by each other in opposite directions.
  4. sliding in the same direction.
Answer: 1. Hint: When the plates run into each other, one plate "crumples" and forms mountains as the other plate slides under.

What happens to the crust where extension occurs?

  1. It bulges upward, forming a mountain range.
  2. It sinks down into the mantle, forming a basin.
  3. It stretches, forming cracks and valleys.
  4. Nothing, Extension does not change the crust.
Answer: 3. Hint: In this case, the crust is stretched out, and when it "tears" it forms cracks and valleys.

Imagine an impact occurred on the continental plate millions and millions of years ago, leaving a crater near the base of the volcano. Why would there be little evidence of this crater found today?

  1. The continental plate would be melted, along with the crater.
  2. More recent impacts would make craters that would erase the old ones.
  3. Lava flows from the volcano would cover it up over time.
Answer: 3. Hint: Volcanoes sit on continental plates that don't get melted during plate tectonics, but they do put out a lot of lava...

In the image below, how heavily covered with craters is Mars?

  1. The surface was almost entirely covered with craters.
  2. There was a medium number of craters, spread all over the surface.
  3. There was a medium number of craters, mostly on one side of the planet.
  4. There were a small number of visible craters.
  5. There were no craters visible.
Answer: 3. Hint: This is mostly a test of your skills at observing. The northern hemisphere of Mars has very few craters compared to the southern hemisphere - possibly because there was once an ocean in the north.

Is there a relationship between the number of craters and either the distance of the planet from the Sun or the size of the planet?

  1. Planets that are closer to the Sun have more craters.
  2. Planets that are closer to the Sun have fewer craters.
  3. Larger planets have more craters.
  4. Larger planets have fewer craters.
  5. There is no apparent relationship.
Answer: 4. Hint: This may not seem to make sense, but the larger planets definitely have fewer craters. Some reasons: their atmospheres help melt smaller space rocks before they hit the surface, water erosion can erase some craters, and volcanic activity or tectronics can cover them up or completely destroy them.

Imagine the pictures below were taken of an area of the Moon with craters at various times in the past. What is the correct order of the pictures from past to present?

  1. I, II, III
  2. I, III, II
  3. II, III, I
  4. II, I, III
  5. III, I, II
  6. III, II, I
Answer: 4. Hint: Craters that overlap help: the one on the "bottom" must have been there the longest. The total number of craters also helps: more creaters means that it has been longer since something has "cleaned" the surface.

The dark grey area is one of the Moon's maria. How old is the lava in it compared to the other craters?

  1. The lava is probably older than most of the craters.
  2. The lava is probably about the same age as most of the craters.
  3. The lava is probably younger than most of the craters.
Answer: 3. Hint: Again, the idea of "overlapping" helps tell which feature was laid down most recently.

In the picture of Mars' surface below, there are several overlapping features. ``A'' is a volcano, ``B'' and ``C'' are craters, and ``D'' is the surface of the flat plain that surrounds everything. Keeping in mind that the surface of the plain {\it might} have been covered up by lava from another volcano, which is the correct order of their ages (from oldest to youngest)?

  1. D, A, B, C
  2. D, C, A, B
  3. D, A, C, B
  4. B, C, A, D
  5. A, C, D, B
  6. A, D, C, B
Answer: 5. Hint: Look carefully at what overlaps what. Volcano "A" must be oldest because everything overlaps it. Crater "C" has obliterated part of "A" put has been filled in by the lava flow that formed the plain "D". "D" has covered over the lower parts of "A". The crater "B" overlaps both the "A" and "D", so it must be youngest.

In the picture of Mars' surface below, which is older?

  1. The large crater.
  2. The erosion channels.
  3. They are about the same age
Answer: 1. Hint: It appears as if some runoff water broke through the side of the crater, and left some mud on the floor of the crater.

In the picture of Mars' surface below, "A" is the set of gullies, "B" is the crater and splashed rock on the right side, and "C" is the crater at the top. What is the order from oldest to youngest?

  1. A, B, C
  2. A, C, B
  3. B, A, C
  4. B, C, A
  5. C, A, B
  6. C, B, A
Answer: 5. Hint: The crater at top is overwritten by gullies, and the crater at the side has covered up some of the gullies.

In the picture of Venus' surface below, "1" is the set of long cracks (from tectonics), and "2" and "3" are lava domes. What is the order from oldest to youngest?

  1. 1, 2, 3
  2. 2, 1, 3
  3. 2, 3, 1
  4. 1, 3, 2
  5. 3, 1, 2
  6. 3, 2, 1
Answer: 3. Hint: Look at how the two lava domes over lap each other, and how the cracks cut through the domes.

Is there a relationship between the number of volcanoes and either the distance of the planet from the Sun or the size of the planet?

  1. Planets that are closer to the Sun have more volcanoes.
  2. Planets that are closer to the Sun have fewer volcanoes.
  3. Larger planets have more volcanoes.
  4. Larger planets have fewer volcanoes.
  5. There is no apparent relationship.
Answer: 3. Hint: Smaller planets cool off faster because they don't insulate themselves well. The example I used in class was comparing a cooked meatball and a cooked turkey. The inside of a turkey can stay hot hours after it has been taken out of the oven.

Suppose a terrestrial planet the same age as Earth is discovered orbiting another star, and it is your job to predict what it is like. If the planet is known to have mass and size smaller than Venus, but more than Mars, what would be the best prediction based on our understanding of the solar system?

  1. It should have no volcanoes.
  2. It should have volcanoes, but they may or may not be active.
  3. It should have a number of active volcanoes spread evenly over the surface.
  4. It should have a large number of active volcanoes found only in small areas of the surface.
Answer: 2. Hint: Mars has dormant volcanoes. Venus has a fairly large number of active ones (astronomers think). Without knowing exactly how massive this new planet is, we won't be able to predict with any confidence whether the volcanoes are active or not.


Planet Atmospheres

When light from the Sun passes through the gas in a planet's atmosphere, what happens?

  1. The gas removes light having specific wavelengths and produces an absorption line spectrum.
  2. The gas adds light having specific wavelengths and produces an emission line spectrum.
  3. The gas adds all kinds of light and produces a continuous spectrum.
  4. The gas doesn't do anything to the light, leaving a continuous spectrum.
Answer: 1. Hint: Some of the light passing through the atmosphere gets absorbed. See earlier thought questions on light.

What gas in Earth's atmosphere is suspected of causing global warming?

  1. ozone
  2. nitrogen
  3. carbon dioxide
Answer: 3. Hint: Carbon dioxide is the only gas in the atmosphere of Venus, and look what happened with it...

Earth emits a continuous spectrum of light because it is a dense, opaque object with a temperature. Earth's average temperature is similar to that of a human being. What kind of light does Earth emit the most of?

  1. Visible light.
  2. Infrared light.
  3. Ultraviolet light.
  4. Actually the Earth doesn't emit light.
Answer: 2. Hint: The visible light that comes from the Earth is reflected sunlight - Earth does not release visible light on its own because it is not hot enough. Cooler blackbodies release longer wavelength light... like infrared.

What would happen to Earth's temperature if Earth were more reflective?

  1. It would go up
  2. It would go down.
  3. It wouldn't change.
Answer: 2. Hint: Less energy would get absorbed by Earth, so that it wouldn't warm up as much. This partly why people worry about the melting of the polar ice caps with respect to global warming.

What might Mars have been like if it had had a mass and size more like Venus and Earth?

  1. Mars would have active volcanoes today.
  2. Mars would have had a thicker atmosphere.
  3. Mars would have more water, but all or most of it would be ice.
  4. all of the above
  5. none of the above
Answer: 4. Hint: Compare what Venus and Earth are like: they both appear to have active volcanoes, and relatively thick atmospheres. Because Mars would still be cooler than Earth (since it is farther away from the Sun), it probably would have been able to keep more water, although in the form of ice.

The temperature of the parts of Jupiter's atmosphere that we can see from space is around -200 degrees F. What would we see if we look at the visible light portion of Jupiter's spectrum?

  1. A continuous spectrum
  2. An emission line spectrum
  3. An absorption line spectrum
Answer: 3. Hint: The planet is colder than a person, so it can't be emitting visible light. It can absorb some of the Sun's light, while it reflects the rest.


Jovian Planets

Neptune is a deep blue color. Which of the following could be a reason for this?

  1. Neptune is hot enough to be releasing mostly blue light.
  2. Neptune is cold enough to be releasing mostly blue light.
  3. Gases in Neptune's atmosphere absorb most of the blue light coming from the Sun.
  4. Gases in Neptune's atmosphere absorb most of the red light coming from the Sun.
Answer: 4. Hint: Neptune is too cold to release any visible light - what we see is reflected sunlight, which is white. So, for it to appear blue, it has to remove the red light from the mix of light.

Below is a picture of Saturn's moon Enceladus. Which of the following statements about its surface is probably true?

  1. All parts of its surface froze over at about the same time.
  2. The lower left part of the surface probably froze over before the upper right.
  3. The upper right part of the surface probably froze over before the lower left.
Answer: 3. Hint: Notice the lack of craters in the lower left.

You just bought what your jeweler said was a solid gold ring, but you don't trust the jeweler. You measure the mass on a scale and find it to be 10 grams. You measure the volume by dropping it in a full glass of water and measuring how much water spills out. You find out that the volume of the ring is 1.2 cubic centimeters. Which of the following is true?

  1. It is OK - the ring is solid gold.
  2. That *$(#%@ jeweler ripped you off.
  3. There is no way to tell.
Answer: 2. Hint: The average density (total mass divided by total volume) is less than 10 grams per cubic centimeter. The density of pure gold is about 19 grams per cubic centimeter.

A planet discovered orbiting another star was found to have a mass that is 0.7 times Jupiter's mass, and a size that is 1.4 times Jupiter's size (so that its volume is 2.7 times greater than Jupiter's). Which of the following is true?

  1. The planet has a higher density than Jupiter, meaning that it is a terrestrial planet.
  2. The planet has a lower density than Jupiter, meaning that it is a jovian planet.
  3. The planet has a lower density than Jupiter, but it is not possible to tell what kind of planet it is.
  4. The planet has a higher density than Jupiter, but it is not possible to tell what kind of planet it is.
Answer: 2. Hint: The planet has less mass than Jupiter, and it is spread out over a larger volume, so that its average density must be less than Jupiter's. This makes its average density even less like a terrestrial planet (which has higher density).


Formation of the Solar System

If your daring professor sits in the ``CHAIR OF DEATH'' with his arms outstretched and starts himself rotating, what will happen if he pulls his arms in toward his body?

  1. He will start to spin much slower.
  2. He will keep spinning at the same speed.
  3. He will start to spin much faster.
  4. Something horrible will happen...
Answer: 3. Hint: If you have ever watched ice skaters, this should be easy.

What will happen if he moves his arms up and down, parallel to his spin axis?

  1. He will start to spin much slower.
  2. He will keep spinning at the same speed.
  3. He will start to spin much faster.
  4. Something even more horrible will happen...
Answer: 2. Hint: A little harder, but again it comes from watching ice skaters.

What would happen to a cloud that collapsed without any rotation at all?

  1. There would not be planets orbiting the Sun.
  2. The planets would be closer to the Sun.
  3. The planets would be farther from the Sun.
Answer: 1. Hint: With rotation, the collapsing gas can start to orbit the Sun once it starts moving fast enough (like an ice skater pulling in her arms).

What kind of material would you expect to be able to condense out of the gas closest to the Sun?

  1. Snowflakes (icy material).
  2. Dust grains made of rocky material.
  3. Metallic dust grains.
  4. Liquid hydrogen droplets.
Answer: 3. Hint: Which of the substances above melts at the highest temperature? Rocky materials are a close second.

We believe that the denser planets tend to be located nearer the Sun because

  1. it is predicted by Newton's Laws
  2. the gravity of the Sun affects them more.
  3. it was hotter near the Sun when these planets formed.
Answer: 3. Hint: The density of a planet does not affect how strong the gravity is - remember that it just depends on mass. Rock and metal was the only solid raw material available for the terrestrial planets because of the high temperature.

Which of the following statements describes the meaning of condensation?

  1. Solid objects colliding and sticking.
  2. Solid objects colliding and breaking up.
  3. Solid or liquid material turning into gas.
  4. Gas turning into solid or liquid.
Answer: 4. Hint: When water condenses on your soda bottle, what is happening?

Which of the following pairs of planets formed at temperatures below the freezing point of water?

  1. Mercury and Venus
  2. Venus and Earth
  3. Mars and Jupiter
  4. Earth and Jupiter
  5. Jupiter and Saturn
Answer: 5. Hint: Jupiter and Saturn got so big because they had more raw material to start with --- namely, hydrogen compounds like water that could condense into icy material.

Would it have been possible for a large Jupiter-like planet to form in the location of Mars?

  1. yes
  2. no
Answer: 2. Hint: Was the temperature at the location of Mars hotter or colder than the freezing point of water in the early solar system?

As more and more planetesimals get stuck together, new collisions will occur

  1. more frequently.
  2. at about the same rate.
  3. less frequently.
Answer: 3. Hint: As the planetesimals collide and stick, there are fewer objects left to collide. It gets harder for them to bump into each other because there is more space between them.

Which of these facts is NOT explained by nebular theory?

  1. There are two main types of planets: terrestrial and jovian.
  2. Planets orbit in the same direction and plane.
  3. The existence of asteroids and comets.
  4. The number of planets of each type (4 terrestrial and 4 jovian).
Answer: 4. Hint: The number of planets depends on chance --- there could have been more or less depending on how many collisions there were during the formation of the solar system.


Some of the questions above are taken from the following sources:

J. P. Adams, D. J. Loranz, E. E. Prather, and T. F. Slater. Lecture Tutorials for Introductory Astronomy -- Instructor's Guide, 2002 (Prentice Hall).


Number of accesses:

Last update: October 30, 2007