Smartwork ASTR1010
Suppose you are transported to a planet with twice the mass of Earth, but the same radius of Earth. Your weight would __________ by a factor of __________.
increase; 2
The celestial equator
is directly above Earth's equator.
Polaris, the North Star, is unique because it
is the only star in the sky that doesn't move throughout the night.
Io has the most volcanic activity in the Solar System because
its interior is tidally heated as it orbits Jupiter.
If you went to Mars, your weight would be
lower because Mars has lower mass and a smaller radius that together produce a lower gravitational force.
The majority of stars, including the Sun, are on the main sequence. The masses and sizes of main-sequence stars in the H-R diagram are indicated in this figure. Study how the various properties of a main-sequence star are related to one another in the figure. Then select the properties in the list that would increase if the mass of a main-sequence star is increased.
luminosity, temperature, radius
Sunspots, flares, prominences, and coronal mass ejections are all caused by
magnetic activity on the Sun.
As a blackbody becomes hotter, it also becomes __________ and __________.
more luminous; bluer
Aside from their periods, short- and long-period comets differ because short-period comets
mostly orbit prograde, while long-period comets have either prograde or retrograde orbits.
The cosmological principle states that
on a large scale, the universe is the same everywhere at a given time
Kepler's second law says that
planets move fastest when they are closest to the Sun.
Earth's interior is heated by
radioactive decay and tidal effects
The circumference of a circle is equal to 2πr, where r is the radius. If the radius of Earth's orbit is 1.5 × 10^8 km, determine how fast Earth moves along its orbit. Assume there are 365 days in a year.
107588.70 km/hr
If it takes the Moon roughly 28 days to go once around Earth, how many degrees must the Moon move every day?
12.9 degrees
Particles at the very outer edge of Saturn's A Ring are in a 7:6 orbital resonance with the moon Janus. If the orbital period of Janus is 16 hours 41 minutes, what is the orbital period of the outer edge of Ring A?
14.3 hours
Write the following two values in standard notation. 1.60934 x 103 (the number of meters in a mile) 9.154 x 10-3 (Earth's diameter compared to the Sun's):
1609.34 0.009154
The arbitrary division where short-period comets end and long-period comets begin is 200 years. Using Kepler's third law for bodies orbiting the Sun, calculate the semimajor axes for the orbits of a short-period comet with a period of 91.0 years, and for a long-period comet of 1351.0 years. Semimajor axis of short-period comet: Semimajor axis of long-period comet:
20.2 AU 122.2 AU
How many parsecs are in 7,500 light-years? How many parsecs are in 10,000 light-years?
2300 pc 3070 pc
About how long does it take the Moon to orbit Earth?
29 days
How does the spectrum of a distant star reveal the star's chemical composition?
Dark lines, also called absorption lines, within the spectra are "fingerprints" for the different atoms and molecules within a star's atmosphere.
It is unlikely that the Moon formed elsewhere and was captured by Earth's gravity, since it may be impossible for the Earth to capture an object as large as the Moon. It is also of note that the Moon contains an unusually low quantity of volatiles, which are materials like water that are easily vaporized at high enough temperatures. Based on this, and given the moon's density, which of the following formation scenarios of the Moon most closely matches our observations?
The Moon accreted from the debris of the impact of a large object with the surface of the Earth.
For a pair of objects, the center of mass is located
along the line between the two objects, closer to the more massive object.
Saturn's bright rings are located within the Roche limit of Saturn. This supports the theory that these rings
are formed of moons torn apart by tidal stresses.
When light enters a medium from space it
slows down
Moons of the outer planets may provide a home for life because
some have organic molecules AND some have liquid water AND some have an interior source of energy.
In the proton-proton chain, four hydrogen nuclei are converted to a helium nucleus. This does not happen spontaneously on Earth because the process requires
very high temperatures and pressures.
About how long does it take Earth to go around its axis once?
1 day
A hypothetical planet has just two moons. The inner moon completes two orbits in the time it takes the outer moon to complete one. Imagine both are regular moons, meaning they orbit in the direction of the planet's rotation. How many times will the moons experience a "close approach" per complete orbit of the outer moon? These frames show the system every 1/2 orbit of the inner moon:
1 time
If a radioactive element has a half-life of 10,000 years, what fraction of it is left in a rock after 40,000 years?
1/16
If a radioactive element A decays into radioactive element B in 1 half-life of 20 seconds, then after 40 seconds
1/4 of element A will remain.
The following graph shows the number of sunspots counted on the Sun as a function of time. What is the period between the first and second solar cycle on this graph?
10 years
Now imagine that the outer moon has a retrograde orbit. This means the two moons will be orbiting in opposite directions. The inner moon will still complete two orbits for each orbit of the outer moon.Now how many close approaches will the moons experience?
3 times
About how long does it take Earth to orbit the Sun?
365 days
Your task is to convert 86,400 (the number of seconds in a day) and 0.0317 (the mass of a particular moon compared to the mass of its planet) to scientific notation. 86,400 = 8.64 × 10N Enter the correct value for N. 0.0317 = X × 10-2 Enter the correct value for X.(please use 4 decimal places in your answer)
4 3.1700
If the Moon were 2 times closer to Earth than it is now, the gravitational force between Earth and the Moon would be
4 times stronger.
If the radius of an object's orbit is reduced by a factor of 5.00, then in order for angular momentum to be conserved, the velocity must increase by a factor of .
5
Weight refers to the force of gravity acting on a mass. We often calculate the weight of an object by multiplying its mass by the local acceleration due to gravity. The value of gravitational acceleration on the surface of Mars is 0.38 times that on Earth. Assume your mass is 69.00 kg. Then your weight on Earth is 676.20 newtons (676.20 N = m × g = 69.00 kg × 9.8 m/s2). What would be your mass on Mars? What would be your weight on Mars?
69.00kg 256.96N
Assume that you and your sister can both throw a baseball at a speed of 70 km/h. If you are in an airplane traveling at 700 km/h and play catch with your sister who is near the front of the plane (you being toward the rear), how fast would the ball be traveling as seen by an observer on the ground when you throw the ball? How fast would the ball be traveling as seen by an observer on the ground when your sister throws the ball back to you?
770km/h 630 km/h
Two stars have the same luminosity, but Star A is 9.0 times farther away than Star B. How much fainter does Star A appear compared to Star B?
81 times fainter
A bar is a measure of atmospheric pressure, where one bar is equivalent to Earth's atmospheric pressure at sea level. Venus's atmosphere has a pressure of 92 bars. Water pressure in Earth's oceans increases by one bar for every 10 m of depth. How deep would you have to go to experience pressure equal to the atmospheric surface pressure on Venus?
920 meters deep
A new star is forming inside this glowing cloud of gas. The dark band in the middle is made of a disk of thick dust, which obscures the light within it and hides the forming star from view. Newly forming stars are surrounded by gas and dust. Based on this observation, what is the most likely scenario for the formation of the Solar System?
A cloud of gas and dust collapsed into a flattened disk, within which the Sun and planets formed.
Which of the following is a reason that all large astronomical telescopes are reflecting telescopes?
A.Reflecting telescopes are not as heavy as refracting telescopes. B.Reflecting telescopes minimize chromatic aberration. D.Reflecting telescopes can be designed to be shorter than refracting telescopes.
Choose all that apply. CCD cameras are better astronomical detectors than the human eye because
A.the integration time can be longer. B.their quantum efficiency is higher. D.they can observe at wavelengths beyond the visible.
Sort each scenario into the category indicating whether or not the car is accelerating.
Accelerating = Slowing Down (Decreased Speed), Speeding Up (Increased Speed), Constant Speed when turning Not Accelerating = Constant Speed and Constant Velocity (straight)
What determines an asteroid's shape? Compare the images of asteroids below and choose the answer that best fits your observations.
Asteroids have a range of sizes, with the largest being spherical and the smaller ones irregular in shape.
Based on the relation shown here between rising carbon dioxide (CO2) concentrations and average global temperatures, what is a logical prediction about what would happen if CO2 levels were to continue to rise?
Average global temperatures would increase.
Why did the Moon move away from Earth billions of years ago?
Back when the Moon was formed, the tidal forces between Earth and the Moon were much stronger. As these tidal forces acted between Earth and the Moon, a natural part of this interaction was the Moon being moved into a higher orbit, triggering the Moon to begin receding from Earth.
If your hypothesis has passed nine tests, but fails the tenth one, what do you do?
Change the hypothesis or create a new one, then come up with new predictions and conduct more tests.
After it was discovered, astronomers predicted Uranus's orbit using Newton's laws of motion and gravity, which had worked extremely well for all of the other planets. To their surprise, they found that their observations of Uranus's motion through the sky did not match their predictions. Which of the following would be the most logical next step?
Check for other previously undiscovered factors that might alter Uranus's orbit while still allowing it to obey Newton's laws of motion and gravity.
The figure shows the orbits of several short-period comets as viewed from above the Solar System, as well as the orbits of some planets. Sort the given bodies by the direction of their orbital motion.
Clockwise: Comet Halley Counterclockwise: Saturn, Jupiter, Comet Encke
The following image represents a section of the H-R diagram. Use the image as a guide to rank the stars according to their relative temperatures, from coolest to hottest.
Coolest = Betelgeuse Aldebaran The Sun Polaris Vega Hottest = Rigel
Which way do most objects travel when viewed from far above the North Pole of Earth?
Counterclockwise
What is the small object to the right of the asteroid Ida?
Dactyl, its moon
On which of the following does plate tectonics occur?
Earth
Lava flows on the Moon and Mercury created large, smooth plains. We don't see similar features on Earth because
Earth has plate tectonics that recycle the surface.
The Sun rotates once every 25 days relative to the stars. The Sun rotates once every 27 days relative to Earth. Why are these two numbers different?
Earth moves in its orbit during this time.
If the Sun instantaneously stopped giving off light, what would happen on Earth?
Earth would get dark 8 minutes later.
What causes the angle of the Sun to change over the year?
Earth's North Pole always points in the same direction in space. Sometimes this is toward the Sun, and sometimes it's away from the Sun.
A lunar eclipse occurs when the ________ shadow falls on the ________.
Earth's; Moon
Order the following images from smallest to largest structure to give our cosmic address.
Earth, Solar System, Milky Way Galaxy, Local Group
What did Kepler's 1st law introduce to orbits that removed the need for all epicycles?
Elliptical orbits
A chunk of iron weighing a few kilograms flies into the inner Solar System, is captured by Earth's gravity, enters the atmosphere burning brightly, and lands on solid ground. Three different names apply to the different stages of its journey. Place them in order from first to last.
First Stage = Meteoroid Meteor Last stage = Meteorite
Label the positions in the Earth's orbit with the appropriate day in the Northern Hemisphere. In the diagram shown, north is up and south is down. The direction of the Earth's axial tilt is exaggerated.
First, day of summer, fall, winter, and spring
Energy stored in matter itself—mass energy—can be very powerful. Per Einstein's famous equation E = mc2, energy is equivalent to mass times a constant (the speed of light squared). The speed of light is very large, so just a small amount of mass can result in a very large amount of energy. How can mass turn into energy?Consider the two most common elements in the universe: hydrogen and helium. As shown in this figure, a hydrogen nucleus (where most of its mass is contained) is made of one proton (p). A helium nucleus is made of two protons and two neutrons (n). Nuclear reactions can change what a nucleus is made of.The mass of hydrogen is 1.6726 x 10-27 kg, and the mass of helium is 6.6465 x 10-27 kg. Given this, which of the following nuclear reactions would result in a decrease of total mass, and thus a release of energy, while keeping the same number of particles involved?
Four hydrogen nuclei combine into one helium nucleus.
The image provided shows a light source moving relative to three different observers: Fred, Velma, and Daphne. If the light source is emitting green light and moving with sufficient speed, identify which colors each person could possibly see.
Fred - Red Light Velma - Blue Light Daphne - Green Light
Study the size difference of the gas giants as shown in the above image (distance from the Sun increases from left to right), and choose the best explanation below for your observations.
Gas giants decrease in size with increased distance from the Sun because the Solar Nebula was less dense farther out.
The diagram shown illustrates the location of the Solar System's eight planets and three large dwarf planets. Sort each object according to its basic composition.
Gaseous - Jupiter, Saturn, Uranus, Neptune Rocky - Mercury, Venus, Earth, Mars, Ceres Rock/Ice Mixture - Pluto, Eris
Sort the positions marked on the diagram of Earth into categories based on whether they are experiencing high or low ocean tides when the Moon is in the location shown. You may neglect the effects of Earth's rotation.
Hight Tide: 0,180 Low Tide: 90, 270
Label these important reference points. Their location in your sky depends on your location on Earth.
Horizon, North Celestial Pole, Zenith, Celestial Equator
The Voyager spacecraft made close-up observations of Saturn's rings that seemed to have no explanation. In particular, Saturn's F Ring appeared twisted, which apparently did not follow Newton's law of gravity and the expected orderly orbits of particles through collisions and gravitational interactions. Given this observation, what is the most logical step in the scientific process?
In keeping with the laws of physics, further observations must be made to search for previously undiscovered objects that might gravitationally influence the rings.
A clue to the process of planetary formation comes from meteorites, which are pieces of debris that have fallen from space to Earth. Most meteorites are made of materials that have remained unchanged since the time that the Solar System was first forming, which make them excellent indicators of what conditions were like during that time. Study this picture of a meteorite that has been sliced open to show its interior, and use your observations to determine the most likely formation scenario for a planet.
Individual particles in the nebula stick together to form larger pieces which later collide with and stick to other pieces to gradually form larger objects, which eventually grow to the size of a planet.
Planets must form somehow within the flattened protoplanetary disk. A clue to this process comes from meteorites, which are pieces of debris that have fallen from space to Earth. Most are made of materials that have remained unchanged since the time that the Solar System was first forming, which make them excellent indicators of what conditions were like during that time. Study this picture of a meteorite that has been sliced open to show its interior, and use your observations to determine the most likely formation scenario for a planet. Scroll down and select the best answer below.
Individual particles in the nebula stick together to form larger pieces, which later collide with and stick to other pieces to gradually form larger objects, which eventually grow to the size of a planet.
Sort the particles into the categories describing whether they are input particles that get used up in the reaction, new output particles persisting after the reaction, or intermediate particles that exist only temporarily during the reaction.
Input - Hydrogen, Electron Output - Neutrino, Gamma Ray, Helium-4 Intermediate - Deuterium, Helium-3, Postiron
Because of its small size, Mercury has lost most of its internal heat from its formation and is nearly geologically dead. Io is smaller than Mercury, but it is the most geologically active object in the Solar System, with volcanic eruptions constantly repaving its surface. This image shows a couple of volcanic eruptions as they happen. Of the four large Galilean moons orbiting Jupiter, Io is the closest to the planet. Considering Io's size and location in the Solar System, what is the most likely reason for Io's high level of geological activity?
Io's proximity to Jupiter provides a current source of internal heat.
If a quantity is conserved, it means that it
It doesn't change
Uranus is visible to the naked eye, a bit brighter than the faintest naked-eye stars. However, it was not until well after the invention of the telescope in the late 18th century that Uranus was accidently discovered. How could people have missed this naked-eye planet until then? Compare Uranus's properties in the following chart to the other planets, then select the option that could explain why Uranus was harder to discover.
It has a longer orbital period than Jupiter and Saturn.
What is a neutrino? Did the neutrino enter the reaction, or was the neutrino produced in the reaction?
It is an almost massless, neutral particle that is produced in nuclear processes. The neutrino was produced in the reaction.
What determines if a planet is Superior?
It is farther from the Sun than the Earth
Whether a planet has an atmosphere or not depends on a number of factors: mass, temperature, composition of the crust, volcanic activity, and complex evolutionary processes. Rank the planets according to how well they retain their atmospheres, using the following criteria: • The planet that still maintains its primary atmosphere, ranks first. • The planet that lost its primary atmosphere but retains a dense secondary atmosphere, ranks second. • The planet that lost its primary atmosphere and retains a tenuous secondary atmosphere, ranks third. • The planet that retained neither its primary nor secondary atmospheres, ranks last.
Jupiter (Most successful) Venus Mars Mercury (Least Successful)
The radiation belts around Jupiter are much stronger than those found around Earth because
Jupiter rotates faster than Earth.
Beside rings, all of the giant planets have many moons that orbit them, some of which are comparable in size to Mercury. Compare the following images of the Moon, Mercury, and Jupiter's moon, Io, and choose the image that has the geologically youngest surface (has been changed most recently). Note: There is a difference between volcanoes, which look like circular blemishes on the surface, and impact craters.
Jupiter's Moon, Io
Suppose you read on the Web that a new planet has been found. Its average speed in its orbit is 33 kilometers per second (km/s). When it is closest to its star, it moves at 31 km/s, and when it is farthest from its star, it moves at 35 km/s. This story is in error because
Kepler's second law says the planet must move fastest when it is closest, not
Research has supported the hypothesis that the wind is responsible for the motion of sailing rocks. There is evidence that wind can set the rocks moving when the ground becomes muddy or when thin layers of ice form beneath the rocks. This scenario has not been falsified by any tests conducted so far, and it is currently the favored explanation within the scientific community. What is the next step in the scientific process?
Make further predictions about this hypothesis and conduct more tests, abandoning or revising the hypothesis if any of the tests are failed.
Once we have come up with a number of plausible hypotheses to explain the "sailing rocks" phenomenon shown, what is the next step we should take, according to the scientific method?
Make predictions for each hypothesis, which will be observed if that hypothesis is correct.
In 1500s, Copernicus reintroduced the heliocentric model that the ancient Greeks had rejected, and it began to gain favor among some scientists. He suggested that the planets all orbit around the Sun in perfect circles, as shown in the figure to the right. This offers a much more elegant explanation of retrograde planetary motion than the geocentric model. What would be the next step in the scientific process for the Copernican heliocentric model?
Make predictions from Copernicus's model, and verify them with observations.
Rank, from greatest (at top) to smallest (at bottom), the seasonal variations of the terrestrial planets.
Mars (Greatest) Earth Venus Mercury (Smallest)
What is the most likely reason for the different levels of geological activity between the Galilean moons?
Moons farther away from Jupiter experience weaker tidal heating.
Sort each picture of the Moon by the phase it is in. You may need to use the scroll bar to see all four categories.
New = Black
Uranus's orbit did not appear to behave according to Newton's laws of motion and gravity. The most likely culprit for Uranus's misbehaving orbit was the gravitational influence of another planet. Using Newton's laws, astronomers were able to calculate exactly where they would expect this still-undiscovered planet to be. When telescopes were pointed at this position, Neptune was seen. What does this imply?
Newton's laws have been verified by yet another test, so we should use them with high confidence until and unless they are falsified by future tests.
The scientific method works well when it is used properly, but ignoring the rules, not looking at results in an objective manner, and flat-out cheating can lead to bad science. We must therefore be careful along every step of the scientific process, including the selection of which evidence to consider for a hypothesis. Consider the following scenario: A person sees a UFO in the middle of the night while walking alone on the beach. No other evidence of the UFO is left behind at the scene. Would the anecdotal verbal account from this witness be valid scientific evidence of the event?
No, because follow-up tests conducted by others cannot verify it.
Label these important places on the celestial sphere.
North Celestial Pole, South Celestial Pole, Celestial Equator, Ecliptic
Ganymede, Europa, and Io share a 4:2:1 resonance in their orbits around Jupiter. If Io's orbital period is 1.77 days, what are the orbital periods of Europa and Ganymede? Note that Io is the innermost of the three moons, and Ganymede is the outermost.
Orbital Period of Europa: 3.54 days Orbital Period of Ganymede: 7.08 Days
Studying the climate on other planets is important to understanding the climate on Earth because
Other planets offer a range of extremes to which Earth can be compared AND underlying physical processes are the same on every planet AND comparing climates on other planets helps scientists understand which factors are important.
If all the inner planets formed from the same processes, why would Earth and Mars be the only ones with moons? One possibility is that it was difficult for the inner rocky planets to acquire moons, and Earth and Mars obtained theirs only through some lucky event. We can compare the three moons to each other and to other objects in the inner Solar System to get an idea of what might have happened. Shown below are images of the moons, with information about their sizes and densities. Also shown are the sizes and densities of some other relatively small objects in the inner Solar System.
Phobos and Deimos have properties that suggest that they are the same type of object as c-type asteroids.
Why do photons take so much longer than neutrinos to emerge from the Sun?
Photons interact strongly with matter, while neutrinos do not.
In 2006, shortly after the discovery of Eris, the International Astronomical Union settled on a physically meaningful definition of a planet: an object that orbits around the Sun, is large enough to be spherical, and has cleared the neighborhood around it of other objects orbiting the Sun. An object that meets the first two criteria, but not the last, was given the new classification of dwarf planet. Sort the objects below according to how they are classified under these new definitions.
Planet - Earth, Saturn Dwarf Planet - Ceres, Pluto, Eris Not a Planet or Dwarf - Eros, Io
The following chemicals either have been or are now part of terrestrial planet atmospheres. Determine whether each is found in either a planet's primary or secondary atmosphere.
Primary Atmosphere - Helium, Hydrogen Secondary Atmosphere - Carbon Dioxide, Nitrogen, Oxygen, Water
Sort each of the five terrestrial bodies into the appropriate category based on the type of atmosphere it currently retains, if any.
Primary Atmosphere - None Secondary Atmosphere - Venus, Mars, Earth No Atmosphere - Mercury, Earth's Moon
As shown here, the eye is an optical device that has several components that are analogous to features of another optical device—the telescope. Match each telescope component with its ocular equivalent. You may need to use the scrollbar to view all of the categories.
Pupil - Aperture Retina - CCD Optic Nerve - Wiring to Computer Lens - Objective Lens Iris - N/A
The problem of atmospheric seeing motivated the development of adaptive optics. This technology can correct for the change in the path of light in real time, with mirrors that deform to redirect the light rays back into a straight path to the detector. This produces images with much higher resolution, as in the figure below. The original view of the object is on the left; the version improved with adaptive optics is on the right. Besides adding adaptive optics to a telescope, what else can be done to reduce the effects of seeing?
Put the telescope at a higher altitude (the height above sea level).
Which of the following can be observed from Earth's surface?
Radio Waves, Visible Light
Electrons prefer to be in the lowest ground state energy level and will therefore spontaneously fall back to this state when excited, releasing the excess energy in the form of light emitted in a random direction. Given this, what would observer 2 (who does not see the star through the gas) observe in the spectrum of the cloud of gas in the picture above? Select the appropriate spectrum below.
Red to Purple, All Black, Lime Green Line in the Middle
Chromatic aberration occurs when white light passes through a lens and the colors of light separate and refract at different amounts. The provided figure depicts chromatic aberration, but with the colors removed for the sake of the question. Rank each of the following colors by how much each refracts, from most (at top) to least (at bottom).
Refracts Most = Blue Green (in the middle) Refracts Least = Red
The colored bands of Jupiter and Saturn are due in part to their compositions: Water and ammonia clouds reflect white light, and ammonium hydrosulfide clouds reflect brown and red light. Alternating cells of rising and falling air can bring ammonia to higher altitudes, where it can condense into visible clouds, or they can push the air down into lower altitudes, making the deeper ammonium hydrosulfide cloud layer visible. The bands of Jupiter are more obvious than those of Saturn, with brighter and more highly varying colors. Compare the cloud layers of Jupiter and Saturn shown to determine why.
Saturn's different cloud layers are deeper, making them harder to see.
On rare occasions, comets have been seen orbiting the Sun. These are planetesimals made of rock and ice that become visible to us when their ice sublimates at the closest approach to the Sun, making them glow brightly and grow tails. Where do they come from? We can answer that question by studying the orbits of the comets that pass close enough to us that we can observe them. We see two distinct types of orbits: short-period and long-period comets.
Short-period comets come from some location near the ecliptic plane of the Solar System, and long-period comets come from farther away, with random directions in a spherical distribution around the Sun.
The following graph shows multiple transit events recorded while observing a star. The colored arrows indicate transits caused by three different planets. Rank the orbital periods of these planets, from shortest to longest.
Shortest Period - Red Planet Blue Planet Longest Period - Purple Planet
Asteroids are
Small rock and metal objects orbiting the sun
Examine the following images that were taken simultaneously of the same part of the Sun but at different wavelengths. What do the images tell you about the relationship between sunspots and solar flares?
Solar flares happen where there are sunspots.
How could Cassini "contaminate" a moon?
Some microorganisms from Earth can survive the environment of space, thus contaminating any moon they land on.
Which of the following is the biggest disadvantage of putting a telescope in space?
Space telescopes are much more expensive than similar ground-based telescopes.
From the vantage point of Earth in the diagram shown, how will the parallax of Star A compare to that of Star B?
Star A has twice the parallax of Star B.
Stars A and B appear equally bright, but star A is twice as far away from us as star B. Which of the following is true?
Star A is 4 times as luminous as star B.
The following graphs plot the number and latitude of sunspots. The top graph shows the number of sunspots counted on the Sun as a function of time. The bottom graph plots individual sunspot latitudes on the Sun as a function of time. It is sometimes called a "butterfly diagram" because of its shape. Identify the statement that best describes how the latitude of sunspots varies over a sunspot cycle, which is defined to begin at solar minimum.
Sunspots are at higher latitudes at the beginning of a cycle, and lower latitudes at the end of the cycle.
Newton determined that the force of gravity on an object is proportional to its mass, causing its mass to be canceled out (Newton's second law) and resulting in a constant acceleration. If the laws of physics are universal, then Newton should be able to apply his discoveries about gravity on Earth to the motion of the planets in our Solar System. Newton's third law says that for every force there is an equal reaction force in the opposite direction. What does this imply about the force of gravity associated with a person standing on the Earth?
The Earth's gravity pulls downward on the person, and the person's gravity pulls upward on the Earth.
The Moon's bulge used to be nonaligned with the line connecting the Earth and the Moon, just like Earth's bulge is now. Earth pulled on the bulge of the Moon, slowing its rotation until it was aligned with the Earth. Therefore, we always see only one side of the Moon from Earth (synchronous rotation, as shown in the figure). If these tidal forces naturally cause synchronous rotation for each object, why is the Moon currently in synchronous rotation with the Earth, but the Earth is not in synchronous rotation with the Moon?
The Moon is much less massive than the Earth, so it will take longer for it to slow the Earth into synchronous rotation.
There is friction between the layers of the Earth, which causes the tidal bulge to be dragged along as the Earth rotates, pulling it out of alignment with the line connecting the Moon and Earth. The gravity of this off-center bulge has an effect on the Moon. Study the above figure, and choose the statement below that follows from it.
The Moon used to be closer to Earth than it is now.
Why does a solar eclipse move across the surface of the Earth?
The Moon's motion from west to east, with respect to the stars, causes the Moon's shadow to move from west to east.
Weather is quite different from climate. Weather describes short-term variations in temperature in a localized place on Earth, while climate refers to the overall average temperature in a large region over a long period of time. To get an accurate indication of where Earth's temperature is heading in the long term, we must look back over a long period of time at the average behavior of the climate as a whole, ignoring short-term changes in weather. With this in mind, study the plot below. How has the global climate been changing over the past 100+ years?
The climate is getting warmer with time.
Why do Jupiter and Saturn appear red/white and brownish orange, while Uranus and Neptune are blue? From the following figures displaying the composition of the Jovian planets with depth, choose the most likely reason for this difference. Note that we are looking at/through the upper cloud layers of each planet, which gives us the perception of a visible surface. Labels of "ice" in the figure refer to clouds made of tiny ice crystals, not a solid layer of ice.
The cloud tops of Jupiter and Saturn have a different composition from the cloud tops of Uranus and Neptune.
The nebular theory states that star systems form by the gravitational collapse of a cloud of gas and dust that, to match observations, must flatten into a disk within which planets can form. Why would this flattening occur? Consider the law of conservation of angular momentum, which states that a quantity related to the size of an object (its moment of inertia) times the speed of rotation (angular speed) has to remain the same at all times as long as no outside forces act on that object. Based on this law, if a collapsing cloud is isolated in space with no external forces, what must happen to it as its size decreases?
The cloud will spin faster.
The following graph shows the concentrations of carbon dioxide (CO2) and methane (CH4) in Earth's atmosphere for the past few hundred thousand years along with global temperatures. How do the current levels of carbon dioxide and methane in the atmosphere compare with the values seen over the last 800,000 years?
The current concentrations of both are far higher than the rest of the graph.
Newton's second law says that the acceleration (a) of an object depends on its mass (m) by the equation: a=F/m F is the force that is causing the object to accelerate. In the case of dropping objects from a height, the force that causes them to accelerate toward the Earth is gravity. If the acceleration of objects dropped from a height does not depend on the object's mass (as shown by Galileo's experiment), what does this imply about the force of gravity?
The force of gravity increases with increased mass.
Newton developed a universal law of gravitation that can be used under most circumstances, not just for objects on the surface of the Earth. Here is the law:𝐹=𝐺(𝑚1𝑚2)/𝑟2 where G is a constant. Think about what happens when you increase and decrease each of the variables in Newton's equation for the gravitational force between two objects of mass m1 and m2, a distance r from one another. Given your results, what is the likely cause of Kepler's observation that planets travel faster when they are closer to the Sun?
The force of gravity is stronger closer to the Sun.
From our vantage point on Earth, it looks like the Earth is stationary, and the Sun, Moon, stars, and planets are orbiting around us. Humans believed this geocentric (Earth-centered) view of the universe for the majority of history. The geocentric model of the universe looked like the left figure shown, with all celestial objects orbiting Earth in perfect circles. The brightest planets are visible to the naked eye, and they move through the background of the stars from one night to the next. Study the picture, which shows Mars's position with respect to the stars over the course of many nights. What can you conclude from this, assuming that the geocentric model holds that the Sun, Moon, and planets like Mars all orbit around Earth in simple circles?
The geocentric model is wrong because it falsely predicts that Mars should always move in the same direction with respect to the stars.
How does the heliocentric model explain the retrograde motion of Mars?
The heliocentric model explains retrograde motion because Mars only appears to move backward as Earth passes it in its orbit around the Sun.
If the Moon had twice the mass that it does, how would the strength of the lunar tides change?
The highs would be higher and the lows would be lower.
To explain the fact that summer is hotter than winter, we can hypothesize that seasons are caused by a variable distance between the Earth and the Sun at different times of the year. Now consider the following facts that relate to this hypothesis:- The Earth's orbit is elliptical (not a perfect circle).- The Southern Hemisphere experiences opposite seasons from the Northern Hemisphere.- The intensity of light from a source is stronger closer to the source.- The Earth's closest approach to the Sun is in January.Is the hypothesis that the seasons are caused by a variable distance between the Earth and the Sun verified or falsified by the evidence?
The hypothesis is falsified because some of the evidence is against it.
If you use the same force to push on two different cars, which will have the bigger acceleration?
The less massive one
Which is not true about the vernal and autumnal equinoxes?
The motion of the stars in the sky on the equinoxes is different than on other days.
What happens to the appearance of an object as it gets hotter?
The object gets brighter. The object gets bluer.
The rings of Saturn were discovered by Galileo using the first telescope to gaze at the night sky. They are bright and large enough to be visible even with the smallest of astronomical telescopes. If Saturn's rings are made of individual small particles at varying distances from the planet, and given what you know of the laws of physics as governed by gravity, how would you expect these particles to behave?
The particles closer to Saturn will orbit faster around the planet than those farther away.
Rank the following in order of size, from smallest to largest.
The radius of Earth, A light-minute, The distance from Earth to the Sun, A light-hour, The radius of the Solar System, A light-year
What is the primary reason the Moon cooled quicker than the Earth?
The radius of the Moon is less than Earth.
Celestial motions over time periods longer than a day are less obvious. Say you went out at exactly the same time each night and looked at the sky, noting the position of a specific set of stars at that time with respect to reference objects on Earth, such as trees and buildings. The following figure shows how the stars would change position. Based on this figure, what is the most correct conclusion?
The stars appear to move westward from one night to the next.
How would you explain the difference in cratering between these two pictures?
The surface on the right has experienced more recent volcanism or erosion than the surface to the left.
Space telescopes that exist in orbit above most of Earth's atmosphere are expensive, so they must therefore be supported with a very compelling motivation. If you were trying to justify funding for a space telescope in orbit around the Earth, which of the following would be the best argument to use?
The telescope could observe wavelengths of light that are not visible from the ground.
When we are faced with more than one hypothesis that has not been falsified by the evidence, Occam's razor tells us that the one that makes the fewest assumptions is most likely to be correct. An assumption is a condition that must be true for our hypothesis to work, but that we cannot prove one way or the other. Which of the following hypotheses about the bizarre motion of sailing rocks relies on the fewest assumptions?
The wind moves the rocks.
The following graph shows the relative concentrations of carbon dioxide (CO2) and methane (CH4) in Earth's atmosphere for the past few hundred thousand years. What, if any, correlation is there between the concentrations of carbon dioxide and methane?
Their concentrations appear to rise and fall together.
Imagine that you are observing a car that is out of control and spinning on the ice on the highway. The car suddenly stops spinning and starts spinning in the other direction as it slides down the highway. In order for this to happen, what must have taken place?
There must have been external forces acting on the car—for example, the spinning car struck another car.
Astronauts in a space shuttle can float while orbiting Earth. Why are these astronauts weightless?
They are falling around Earth at the same rate as the shuttle.
Why are Ganymede and Callisto geologically dead while the other two Galilean moons of Jupiter are active?
They are farther from Jupiter.
Why does the angle of the Sun's rays matter in regard to Earth's seasons?
They are more spread out if they strike at an angle.
Kuiper Belt objects (KBOs) are actually comet nuclei. Why do they not display comas and tails?
They are too far from the Sun.
Why don't we see cars as bluer when they approach and redder when they recede?
They are too slow.
This chapter deals with leftover planetesimals. What became of most of the others?
They became part of larger bodies.
Why are dwarf planets considered planets despite being smaller than some moons?
They do not orbit a body other than the Sun.
How did the ancients know the planets were different from the stars?
They saw that the planets move with respect to the stars over the course of many nights.
There is a particle produced in the Sun's nuclear reactions that we can use to directly study what is happening in the interior. Neutrinos are weakly interacting particles, and they have almost no mass and no charge. They are not affected at all by the nuclear strong force. As neutrinos travel through the Sun's dense interior, how will their path change due to the presence of the gravitational, electromagnetic, and nuclear strong forces around them?
They will not change at all.
Why were the exposures in this article taken 6 months apart?
This provides the largest possible angular shift of the star between exposures.
The diagram shown indicates the location of exoplanets orbiting their star. The light green ring represents the habitable zone for that star. Determine whether each of the planets in this system is located in a region that is too hot, too cold, or just right for liquid water to potentially exist on the surface.
Too hot for liquid water - Planet b, c, d, e Too cold for liquid water - None Just right for liquid water - planet f
According to the object orbits shown on the vertical axis at left of the graph, identify each orbit as either unbound, circular, or elliptical.
Unbound: Orbit 3 and 4 Circular: Orbit 1 Elliptical: Orbit 2
Which of the giant planets has the most extreme seasons?
Uranus
Neptune's existence was predicted because
Uranus did not obey Newton's laws of motion.
Do a web search for Solar System objects that have a possibility for life. Which one of these objects has the least chance of harboring life?
Venus
Which of the following worlds does not show evidence of the current presence of liquid or frozen water?
Venus
Venus is hot and Mars is cold primarily because
Venus has a much thicker atmosphere.
The following graph shows the concentrations of carbon dioxide (CO2) and methane (CH4) in Earth's atmosphere for the past few hundred thousand years along with global temperatures. What is the correlation between concentrations of these two chemicals and global temperature?
When concentrations are high global temperatures are high.
If Earth's axis were tilted by 45°, instead of its actual tilt, how would the seasons be different than they are currently?
Winters would be colder.
The atmosphere absorbs some light before it can reach a telescope's detector, making objects appear fainter. The exact amount of absorption depends on the wavelength of light being observed, as shown in this graph of the percentage of light that can make it through the atmosphere to the ground. 0% transparency (atmosphere is opaque) means no light gets through, and 100% transparency means all the light gets through. The type of light per wavelength is labeled at the bottom of the figure. Visible light is marked by the rainbow. Based on the above graph, which of these types of light from astronomical sources are not observable from the ground?
X-Ray, Infrared at 100 micrometer, Ultraviolet at 100cm, Gamma Ray
Imagine a planet moving in a perfectly circular orbit around the Sun. Is this planet experiencing acceleration?
Yes. It is changing its direction of motion all the time.
Imagine you are walking along a forest path. Which of the following is not an action-reaction pair in this situation?
You push down on Earth; Earth pushes you forward.
A light wave does NOT require
a medium in which to propagate
When an electron moves from a higher energy level to a lower energy level in an atom,
a photon is emitted.
The nucleus of a comet is mostly
a porous mix of ice and dust.
According to the data, the global average temperature of the Earth is increasing. Based on the two plots below, what is likely causing this?
a sudden increase in the strength of the greenhouse effect over the past 100-200 years
The average distance of Mars from the Sun is 1.4 AU. How bright is the Sun on Mars compared with its brightness on Earth?
about 2 times fainter
If you wanted to search for faint rings around a giant planet by sending a spacecraft on a flyby, it would be best to make your observations
after the spacecraft passed the planet.
For a system in which a planet orbits a star, the center of mass is located
along the line between the planet and the star, closer to the star.
The oxygen molecules in Earth's atmosphere
are the result of life.
Where on Earth can you stand and, over the entire year, see the entire sky?
at the equator
If you were standing at Earth's North Pole, where would you see the north celestial pole relative to your zenith?
at the zenith
The "square" in the inverse square law for intensity of light means that
at three times the distance, the intensity is 1/9 as great.
As a comet leaves the inner Solar System, its ion tail points
away from the Sun.
The tilt of Jupiter's rotational axis with respect to its orbital plane is 3°. If Earth's axis had this tilt, then the seasons on Earth would
be much less extreme.
Why is Jupiter reddish in color?
because of the composition of its atmosphere
When objects get really hot, they turn
blue
When you look at the sky on a dark night and see stars of different colors, which are the hottest?
blue
Imagine that you observe a star/planet system, edge-on. When the planet is moving away from Earth, the light from the star is
blueshifted
Light acts like
both a wave and a particle
An object in a(n) __________ orbit in the Solar System will remain in its orbit forever. An object in a(n) __________ orbit will escape from the Solar System.
bound; unbound
The horizon is defined
by the direction perpendicular to a line to the zenith.
The main greenhouse gases in the atmospheres of the terrestrial planets are
carbon dioxide and water vapor
Over the last 800,000 years, Earth's temperature has closely tracked
carbon dioxide levels in the atmosphere.
No matter where you are on Earth, stars appear to rotate about a point called the
celestial pole
An inferior planet is one that is
closer to the Sun than Earth is.
Perihelion and aphelion describe the points in an orbit that are ___ (respectively) the Sun
closest to and farthest from
When hydrogen is fused into helium, energy is released from
conversion of mass to energy.
Looking down on Earth from above the North Pole, the Moon orbits Earth
counterclockwise
The similarity of Mars' tiny moons to asteroids suggests that they wandered away from the nearby asteroid belt and were captured by Mars' gravity. It is difficult to explain, however, how a relatively small planet like the Earth would be capable of capturing an object as large as the Moon. If it wasn't captured, then it must have either formed simultaneously with the Earth or separated from the Earth due to some event that happened later. We can get an idea of which scenarios are reasonable by looking at the composition of the two, which we can gather from their densities. Examine the figure below, which shows the approximate density of the Earth's layers in g/cm3. If the density of the Moon is 3.34 g/cm3, which layer of the Earth is it most similar to?
crust
As wavelength increases, the energy of a photon __________ and its frequency __________.
decreases; decreases
Cameras that use adaptive optics provide higher spatial-resolution images primarily because
deformable mirrors are used to correct the blurring due to Earth's atmosphere.
Differentiation refers to materials that are separated based on their
density
Which of the following mechanisms contribute significantly to the formation of planetary rings?
destruction of a moon by tidal forces
This image was taken in infrared light by Hubble's NICMOS camera in September 1997. It shows a young star cluster within the Milky Way Galaxy. Why do the stars appear to be different colors?
difference in temperature
Individual cloud layers in the giant planets have different compositions. This happens because
different volatiles freeze out at different temperatures.
A light-year is a measure of
distance
Which is not a reason for the large size of volcanoes on Mars compared to Earth's smaller volcanoes?
distance from the Sun
When Earth catches up to a slower-moving outer planet and passes it in its orbit, in the same way that a faster runner overtakes a slower runner in an outside lane, the outer planet
exhibits retrograde motion.
You see the Moon rising, just as the Sun is setting. What phase is the Moon in?
f
The dynamo theory says that a planet will have a strong magnetic field if it has
fast rotation and a liquid core.
Gravitational interactions with moons produce
fine structure within rings.
Imagine two objects moving away from you. Object A is faster than object B. You will observe that the light
from both objects is redshifted.
CCD cameras have much higher quantum efficiency than other detectors. As a result, CCD cameras can
generate a signal from fewer photons.
Uranus and Neptune are different from Jupiter and Saturn in that Uranus and Neptune
have a higher percentage of ices in their interiors.
Identify the element whose emission spectrum is shown in the graph by comparing it to the known spectra of five different elements.
helium
Oort Cloud objects will only pass close to Earth and become comets if their orbits are:
highly elliptical.
This NASA image shows the first five planet discoveries of the Kepler mission, as well as all known exoplanets in the universe. Based on their size and orbital distance, the Kepler exoplanets are most likely which kind of planet?
hot Jupiters
Occam's razor states that
if two hypotheses fit the facts equally well, choose the simpler one.
At the densities of the Sun, hydrogen nuclear fusion can occur at temperatures greater than about 10 million degrees Kelvin (K). Based on these graphs of the Sun's pressure, density, and temperature in its interior, where are the nuclear reactions occurring?
in a central region 20% the size of the entire Sun
If the velocity of a charged particle is perpendicular to the magnetic field, the magnetic force on the particle will cause it to move
in a circle.
A meteoroid is found _____________, a meteor is found ____________, and a meteorite is found ________________.
in space; in the atmosphere; on the ground
If the distance between Earth and the Sun were cut in half, the gravitational force between these two objects would
increase by a factor of 4.
Arrays of radio telescopes can produce much better resolution than single-dish telescopes because they work based on the principle of
interference
The nebular hypothesis describes what happens when a cloud collapses into a star system. Where does the majority of the angular momentum of the original cloud go?
into the orbital angular momentum of planets
The radial velocity method preferentially detects:
large planets close to the central star.
The spectroscopic radial velocity method preferentially detects
large planets close to the central star.
The transit method preferentially detects
large planets close to the central star.
When an object is farther away, it appears to move _____ against the background than a closer object.
less
Refraction is caused by
light changing speed and bending as it enters a new medium.
The connection between gravity and orbits enables astronomers to measure the __________ of stars and planets.
masses
When viewed through a telescope, Uranus and Neptune are distinctly bluish green in color. What gas is responsible for this striking appearance?
methane
When observed from two widely separated locations, an object appears to move _____ against the background than when observed from two locations near one another.
more
As two objects orbit one another, they are always
on opposite sides of the center of mass, traveling in opposite directions in space.
Two stars are of equal luminosity. Star A is 3 times as far from you as star B. Star A appears _________ star B.
one-ninth as bright as
If the star Polaris has an altitude of 35°, then we know that
our latitude is 35° north.
Suppose an earthquake occurs on an imaginary planet. Scientists on the other side of the planet detect primary waves but not secondary waves after the quake occurs. This observation suggests that
part of the planet's interior is liquid.
If we were to take a snapshot of where the photons are inside the Sun, and which direction they are traveling, we would find that
photons are traveling in all directions.
Hydrostatic equilibrium in the Sun means that
pressure balances the weight of overlying layers.
The structure of the Sun is determined by both the balance between the forces due to _______ and gravity and the balance between energy generation and energy _______.
pressure; loss
As energy moves out from the Sun's core toward its surface, it first travels by _______, then by _______, and then by _______.
radiation; convection; radiation
The words weather and climate
refer to very different time scales AND refer to very different size scales.
Since angular momentum is conserved, an ice-skater who throws her arms out will
rotate more slowly.
This image shows the relative sizes of the terrestrial planets and their order from the Sun (closest toward the left, farthest toward the right). Assume that, based on crater counts, the geological age of the planetary surfaces from oldest to youngest is Mercury, Mars, Venus, Earth. Based on the information above, which of the following properties of a planet is most important in determining its level of recent geological activity?
size
Imagine that a star-forming cloud collapses but retains all of its mass in a single blob. In order to conserve angular momentum, the cloud must
spin faster
Imagine that a star-forming cloud collapses but retains all of its mass in a single blob. In order to conserve angular momentum, the cloud must
spin faster.
If Earth shrank to a smaller radius but kept the same mass, the gravitational force between Earth and the Moon would
stay the same
Volcanoes on Enceladus affect the E Ring of Saturn by
supplying ring particles.
Scientists determine the geological history of the moons of the outer planets from
surface features.
Select the main processes that build up structures on the terrestrial planets.
tectonism, impacts, volcanism
The spectral type of a star is directly related to its color. Recall that a star emits light as a blackbody, which has a particular shape to its spectrum, as shown in this figure. Based on this, what basic property of a star determines its color (and thus its spectral type)?
temperature
When a boat moves through the water, the waves in front of the boat bunch up, while the waves behind the boat spread out. This is an example of
the Doppler effect.
Spring tides occur only when
the Moon is in new or full phase
We always see the same side of the Moon because
the Moon rotates once each revolution.
The primary factor in Earth's tides is
the Moon's gravity.
The chemical compositions of Jupiter and Saturn are most similar to those of
the Sun
Newton's second law of motion states that
the acceleration of an object is proportional to the net force acting on it.
Observations of excited gas in the lab show that every element, molecule, and ion has its own unique set of possible electron energy levels, as shown in the emission spectra below. Based on this fact, what can we find from the wavelengths of absorption lines seen in the spectrum of a star?
the composition of any gas between the light-emitting "surface" of the star and the observer
Meteorites can provide information about all of these except
the current climate of Mars.
The tilt of Earth's axis causes the seasons because
the days are longer in summer AND the rays of light strike the ground more directly in summer.
The direction of revolution in the plane of the Solar System was determined by
the direction of rotation of the original cloud.
Zonal winds on the giant planets are stronger than those on the terrestrial planets because
the giant planets rotate faster.
Auroras are the result of
the interaction of particles from the Sun and Earth's atmosphere and magnetic field.
Scientists know the history of Earth's magnetic field because
the magnetic field freezes into rocks, and plate tectonics spreads the rocks out.
Sunspots change in number and location during the solar cycle. This phenomenon is connected to
the magnetic field of the Sun.
Subsequent semi-diurnal (twice daily) tides happen precisely once every 12 hours and 25 minutes. Given what you know of the motions of the Earth and Moon, where is this extra 25 minutes likely coming from?
the orbit of the Moon around the Earth
Hadley circulation is broken into zonal winds by
the planet's rapid rotation.
Deep in the interiors of the giant planets, water is still a liquid even though the temperatures are tens of thousands of degrees above the boiling point of water. This can happen because
the pressure inside the giant planets is so high.
Compared to your mass on Earth, on the Moon your mass would be
the same; mass doesn't change.
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the surface of Earth
The seasons are caused by
the tilt of the Earth's axis.
Geologists can find the relative ages of impact craters on a world because
the top layer of impact craters is the youngest.
Sunspots appear dark because
they are cooler than their surroundings.
Less massive molecules tend to escape from an atmosphere more often than more massive ones because
they are moving faster.
Spacecraft are the most effective way to study planets in our Solar System because
they can collect more information than is available just from images.
Congress tasked NASA with searching for near-Earth objects because
they might impact Earth, as others have in the past.
What causes the Moon to always keep the same face toward Earth?
tidal locking
Astronomers cannot use parallax to find the distance to most stars. This is because the stars are
too far away.
Imagine that you observe a star-planet system, edge-on. When the planet is moving away from Earth, in which direction is the star moving?
toward Earth
All weather and wind on Earth are a result of convection in the
troposphere
Convection in the _________ causes weather on Earth.
troposphere
Astronomers use two points in Earth's orbit to get the best possible parallax measurement. Even better measurements would be possible with observations from
two points in the orbit of Mars, separated by half a Martian year.
The ozone layer protects life on Earth from
ultraviolet radiation
Under what lighting conditions are the tiny dust particles, found in some planetary rings, best observed?
viewed from the shadowed side of the planet, looking toward the Sun
If a moon revolves opposite to a planet's rotation, it probably
was captured after the planet formed.
The "second" high tide is caused by
weaker gravity pulling on Earth on the side opposite the Moon.
The force of a magnetic field on a stationary charge is
zero