Exam 2 Astronomy
Consider the first major feature (orderly motions). Which of the following correctly describe patterns of motion in our solar system?
*All the planets orbit the Sun in nearly the same plane. *The Sun and most of the planets rotate in the same direction that the planets orbit. *Planets have nearly circular orbits.
Sort the following hypothetical discoveries into the appropriate bins as follows: *Consistent with theory: The statement describes a discovery that we could reasonably expect to find if the nebular theory is correct. *Not consistent with theory: The statement describes a discovery that would force us to modify or discard the nebular theory.
*Consistent: -Beyond its jovian planets, a star has two ice-rich objects as large as Mars. -A star has 20 planets -A star is surrounded by a disk of gas but has no planets. -Of a star's 5 terrestrial planets, 1 has a moon as large as Earth's moon. * Not Consistent: -A star has 9 planets, but none orbit in close to the same plane. -All 6 of a star's terrestrial planets have a moon as large as Earth's moon. -A star's 4 jovian planets formed in its inner solar system and its 4 terrestrial planets formed farther out. -A star's 5 terrestrial planets orbit in the opposite direction of its 3 jovian planets.
Click the third tab (labeled "Global Warming"), then explore the graph and the expanded views you will find by clicking the "?" buttons. Which of the following statements are supported by the data shown?
*Earth's global average temperature has generally risen over the past century. *Atmospheric carbon dioxide levels have risen dramatically over the past century. *Rises in global average temperature tend to be closely associated with rises in atmospheric carbon dioxide concentration.
Complete the sentences correctly.
*If you stand on a scale on the Moon, your weight will be different than it is on Earth but your mass will be the same. *If your momentum is changing, then a(n) net force must be acting on you. *If you are in free-fall, then your weight will be zero. *An object's momentum is its mass times its velocity, and we say that it has angular momentum if it is rotating or turning on a curved path. *On Earth, the acceleration of gravity tells us that the velocity of a falling object increases by about 10 m/s for each second it falls.
Match the words at the left to the correct blanks in the sentences at right.
*Io is the most volcanically active world in the solar system. *Jupiter has three moons for which there is evidence of a global, subsurface ocean of liquid water, with the strongest evidence favoring an ocean on Europa. *The two moons that are larger than the planet Mercury are Titan and Ganymede, which is also the largest of Jupiter's moons (and largest moon in the solar system). *Spacecraft images show fountains of ice spraying into space from Saturn's moon Enceladus. *Scientists have detected lakes of liquid methane and ethane on the surface of Titan.
In analyzing the data from your program, you discover one star that dims by about 0.1% for about two hours on every 63rd day. Assuming the dimming is caused by a single planet, what would you conclude about this planet?
*It has an orbital period of 63 days. *Its size (area of disk) is about 0.1% of the star's size.
Now consider the second major feature (two types of planets). Which of the following statements are true for the terrestrial and jovian planets in our solar system?
*Jovian planets have more moons than terrestrial planets. *Jovian planets are larger in mass than terrestrial planets. *Jovian planets are larger in size than terrestrial planets. *Jovian planets orbit farther from the Sun than terrestrial planets.
Match the words at the left to the correct blanks in the sentences at right.
*Meteor showers are associated with debris from comets. *Pieces of asteroids that have fallen to Earth are called meteorites. *Leftover planetesimals that formed in the region of the solar system now occupied by the jovian planets are called comets. *The objects that are sometimes visible in the night sky with long tails are comets. *Ceres, Pluto, and Eris are all round in shape and classified as dwarf planets. *Leftover planetesimals that formed inside the frost line are known as asteroids.
All the following statements are true. Which of them are considered to be "exceptions" to the general trends described by the first three major features of the solar system?
*Our Moon has a diameter more than 1/4 the diameter of Earth. *Uranus rotates with an axis tilt that lies nearly in the ecliptic plane. *Venus rotates in a direction opposite to the rotation of the other terrestrial planets.
Based on the nebular theory as it explains our own solar system, which of the following should we expect to be true for other star systems?
*Planetary systems should generally have all planets orbiting in nearly the same plane. *Planetary systems should be common. *Jovian planets always form farther from their star than terrestrial planets. *Many extrasolar planets should fall into the terrestrial or jovian categories.
For the purposes of seeking a theory to explain the formation of the solar system, we identify four major features of our solar system. Which of the following represent these four major features?
*Several exceptions to the general trends stand out. *Planets fall into two major categories (terrestrial and jovian). *Swarms of asteroids and comets populate the solar system. *Large bodies in the solar system have orderly motions.
Suppose you monitor a large number (many thousands) of stars over a period of 3 years, searching for planets through the transit method. Which of the following are necessary for this program to detect an extrasolar planet around one of these stars?
*The planet must have an orbital period of less than about 1 year. *As seen from Earth, the planet's orbit must be seen nearly edge-on (in the plane of our line-of-sight). *You must be able to precisely measure variations in the star's brightness with time.
What are four key features of our solar system that any theory of solar system formation must be able to explain?
*There are vast numbers of asteroids and comets. *Planets fall into two major categories: jovian and terrestrial *There are a few notable "exceptions to the rules." *There are clear patterns to the rotation and orbits of large bodies in the solar system.
Suppose you drive from home to your child's school, pick her up, and drive back home, covering a total distance of 25 miles in 1 hour. Which of the following statements are true?
*Your velocity is different on the return home than it is on the way to school *Your average speed for the trip is 25 miles per hour. *You must accelerate when you reach the school.
Click on the first tab at the top of the interactive figure (labeled "The Greenhouse Effect"), then explore what happens as you click among the buttons (labeled "none," "low," "medium," and "high") that adjust the greenhouse gas concentration. Which of the following occur as the greenhouse gas concentration increase?
*more infrared light is absorbed in the lower atmosphere *the average surface temperature rises
Which of the following are forms of light (electromagnetic radiation)?
*radio waves *ultraviolet *infrared *gamma rays *X rays *visible light *microwaves
The solar system contains vast numbers of small bodies, which we call asteroids when they are rocky and comets when they are icy. These small bodies are concentrated in the region(s) of the solar system that we call __________.
*the Kuiper belt *the Oort cloud *the asteroid belt
Which method(s) are based on the gravitational tug a planet exerts on its star and hence can tell us about a planet's mass?
*the astrometric method *the Doppler method
What percentage of the mass of the solar nebula consisted of elements other than hydrogen and helium?
2 percent
Directly detecting an Earth-size planet around one of the nearest stars (besides the Sun) is roughly equivalent to trying to take a picture of a ball point from a pen at a distance of about ________ kilometers.
4000
In order for an atom to absorb a photon (a particle of light),
A.)the photon must have enough energy to remove an electron from the atom. C.)the photon must have energy matching the difference in energy between energy levels in the atom. A or C
As you've seen, the nebular theory predicts that a cloud that gives birth to planets should have the shape of a spinning disk. Which observable property of our solar system supports this prediction
All the planets orbit the Sun in the same direction and in nearly the same plane
Which of the following is not evidence supporting the idea that our Moon formed as a result of a giant impact?
The Pacific Ocean appears to be a large crater-probably the one made by the giant impact.
Compare the acceleration the Moon experiences due to the Earth's gravity and the acceleration the Earth experiences due to the Moon's gravity.
The acceleration of the Moon is greater than the acceleration of the Earth.
Compare the force of gravity on the Moon due to the Earth, and the force of gravity on the Earth due to the Moon.
The forces are equal and opposite.
If one drops a golf ball and a bowling ball simultaneously from the same height above the ground, what will happen? Neglect the effects of wind or air resistance.
The golf ball and the bowling ball will hit the ground at the same time.
Which of the following scenarios would allow an astronomer to measure the density of an extrasolar planet?
The mass of the planet can be measured using the Doppler method, and the planet also transits its star.
Consider the planet that causes the stellar motion shown in Plot 2 (be sure you have clicked the "Plot 2" button in the lower window of the animation). What can be said about a different planet orbiting the same star with an orbital period of 500 days?
The planet must be closer to the star.
Suppose that for one of the planets detected by the transit method in your program, you conduct follow-up observations using the Doppler method. What key additional information will you learn?
The planet's mass and average density.
Consider only the first major feature, which concerns observed patterns of motion in the solar system. Scientifically, which of the following possible conclusions is justified from the patterns of motion alone?
The planets were not each born in a separate, random event
Which one of the following is not one of the four major features of the solar system?
The solar system contains eight planets plus dwarf planets (such as Ceres, Pluto, and Eris).
Notice that the planets with the largest radii all fall in the category of "hot Jupiters," which means Jupiter-like planets that are hot because they orbit close to their stars. Which of the following best explains why these planets are large in radius?
Their high temperatures make their atmospheres expand to larger radii.
Which of the following best describes the nature of planetary rings?
They are composed of countless individual particles.
Any object moving towards or away from the Earth will show a Doppler shift when observed from Earth.
True
Moving two objects 10 times closer to each other will increase their gravitational attraction 100 times.
True
The Moon is constantly falling toward Earth.
True
You are currently emitting electromagnetic waves.
True
Two hypothetical discoveries in Part A deal with moons that, like Earth's moon, are relatively large compared to their planets. Which of the following best explains why finding 1 planet with such a moon is consistent with the nebular theory, while finding 6 planets with such moons is not consistent?
Unusually large moons form in giant impacts, which are relatively rare events.
The two jovian planets that contain the highest proportions of hydrogen compounds are ___________.
Uranus and Neptune
Now click the second tab (labeled "Terrestrial Planet Temperatures"), then explore what happens as you click the button that allows you to add or remove greenhouse gases. Which terrestrial planet would have its surface temperature the most dramatically changed if its greenhouse gases were removed from its atmosphere?
Venus
The planet in our solar system with the highest average surface temperature is ________.
Venus
We now know of many Jupiter-size planets around other stars. Suppose that future observations show that one of these planets has two orbiting moons. What additional information, if any, would we need to decide whether these moons experience tidal heating?
We need to know their orbital periods.
Which of the following statements is not one of Newton's Laws of Motion?
What goes up must come down.
Which object is likely to be the coldest? The object whose light spectrum is brightest in the
X-rays.
For an object producing a thermal spectrum, a higher temperature causes the spectrum to have ___________.
a peak intensity located at shorter wavelength
According to the laws of thermal radiation, hotter objects emit photons with _________.
a shorter average wavelength
We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. What observational evidence confirms that tidal heating is important on Io?
active volcanoes on Io
Consider the hypothetical discovery from Part A reading: "A star's 5 terrestrial planets orbit in the opposite direction of its 3 jovian planets." This discovery would be inconsistent with the nebular theory because the theory holds that __________.
all the planets formed in a rotating, disk-shaped nebula
When the atom's electrons step down to lower energy levels in a thin cloud of hot gas, what is produced?
an emission line spectrum
According to our present theory of solar system formation, why were solid planetesimals able to grow larger in the outer solar system than in the inner solar system?
because only metal and rock could condense in the inner solar system, while ice also condensed in the outer solar system
Today, scientists have a theory (the nebular theory) that explains all the major characteristics of the solar system. In science, we expect a theory like this not only to explain the observed characteristics of our solar system but also to predict __________.
general characteristics of other solar systems
The greenhouse effect raises Earth's surface temperature (from what it would be otherwise) because the infrared light radiated by Earth's surface __________.
is absorbed by greenhouse gases, slowing the escape of this energy to space
Orbital resonance also gives Europa an elliptical orbit, so it experiences tidal heating, too. However, Europa experiences less tidal heating than Io, because Europa __________ than Io.
is farther from Jupiter
Io experiences tidal heating primarily because __________.
its elliptical orbit causes the tidal force to vary as Io orbits Jupiter.
Red light has a _____ wavelength and a _____ frequency than does blue light.
longer, lower
In essence, the Kepler mission is searching for extrasolar planets by____________.
monitoring stars for slight dimming that might occur as unseen planets pass in front of them
Suppose that you had "X-ray vision" that allowed you to see X rays. What would you notice when you looked at a friend standing near you that you could not notice with your visible light vision alone?
nothing
The "giant impact hypothesis" refers to the idea that ___________.
our Moon formed when a Mars-size object collided with the young Earth.
Now consider why the observed patterns of motion lead to the conclusion that the planets were not born in separate, random events. The reason for this conclusion is that, if the planets had been born in separate, random events, we would expect that __________.
planetary orbits would have many different orientations and directions, rather than all being in the same direction and in the same plane
If you have a telescope that is observing light with wavelengths of a few meters, you are observing __________.
radio waves
How do scientists determine the age of the solar system?
radiometric dating of meteorites
We can see each other in the classroom right now because we
reflect visible light.
X ray photons have a _____ wavelength, _____ frequency, and _____ energy than do ultraviolet photons.
shorter, higher, higher
We know how fast a star in the galaxy is moving away from us on the basis of its
spectrum
In the context of studying major bodies of our solar system, what category of object does our Moon best fit?
terrestrial world
Everything looks red through a red filter because
the filter transmits red light and absorbs other colors.
Observations show that interstellar clouds can have almost any shape and, if they are rotating at all, their rotation is not perceptible. However, the nebular theory predicts that a cloud will rotate rapidly once it shrinks to a relatively small size. What physical law explains why a collapsed cloud will rotate rapidly?
the law of conservation of angular momentum
The nebular theory also predicts that the cloud should heat up as it collapses. What physical law explains why it heats up?
the law of conservation of energy
Which of the following properties can be inferred from the star's orbital period?
the planet's orbital radius
The lithosphere of a planet is the layer that consists of
the rigid rocky material of the crust and uppermost portion of the mantle.
Newton's second law states: sum of forces = mass × acceleration. According to this, what property can you determine if you observe the acceleration of an object with a known mass?
the sum total of all forces acting on the object
Suppose that two objects collide. Which of the following things is NOT the same both before and after the collision?
the total temperature of the objects
Which method of planetary detection works only for planets that happen to orbit their star with an orientation that causes them to pass directly in front of the star as seen from Earth?
the transit method
Why are astronauts (and other objects) weightless inside the International Space Station as it orbits Earth?
they are in free-fall
Consider the hypothetical discovery from Part A reading: "Beyond its jovian planets, a star has two ice-rich objects as large as Mars." This discovery is consistent with the nebular theory, because this theory predicts that _________.
this might have happened in our own solar system if it had taken longer for the solar wind to clear the solar nebula
Which planet search technique is currently best suited to finding Earth-like planets?
transit
The difference between speed and velocity is that ________.
velocity also includes a direction
In which of the following cases would you feel weightless?
while falling from a roof
Is it possible to determine the planet's mass from the star's velocity curve?
yes, by measuring both the star's orbital period and its change in velocity over the orbit
Most continuous spectra are examples of what we also call thermal radiation spectra. Why do we call them "thermal" spectra?
Because the peak wavelength of the spectrum depends on the temperature of the object producing the spectrum.
Most interstellar clouds are made mostly of hydrogen (because hydrogen is the most common element in the universe). Why are these clouds usually dominated by the color red?
Because the strongest visible emission lines from hydrogen are red.
Three planets are circled on the planetary mass-radius diagram shown at left. Rank these planets, along with Earth and Jupiter, in order of mass, from highest to lowest. Rank from highest mass to lowest mass. To rank items as equivalent, overlap them.
COROT-14b, Jupiter, HAT-P32b, Kepler 10b, Earth
Click the fourth tab (labeled "Computer Models"), then explore how the graph changes as you click among the three buttons to its left. What is the primary message of the full graph (with all three curves shown)?
Climate models successfully reproduce the major recent trend in temperature data only if both human and natural factors are included.
The nebular theory also predicts that the cloud will flatten into a disk as it shrinks in size. Which of the following best explains why the collapsing cloud should form a disk?
Colliding cloud particles exchange angular momentum and, on average, end up with the rotation pattern for the cloud as a whole.
Sort each item into the appropriate bin based on which type of spectrum it represents. Drag each item into one of the bins below.
Continuous: -a graph of this spectrum shows a smooth curve -arises from relatively dense objects like light bulb filaments, rocks, and people -the only one of the spectra below that does not give us information about chemical composition Emission Line Spectrum: -produced by thin or low-density clouds of gas -a graph of this spectrum has upward spikes Absorption Line Spectrum: -a graph of this spectrum is a curve with sharp, downward dips -produced when starlight passes through a thin or low-density clouds of gas
Electrons orbit an atomic nucleus like planets orbit the Sun.
False
Grass is green because it absorbs green light, reflecting all other colors.
False
When energy is converted from one form to another, a tiny amount is inevitably lost.
False
Consider the same set of planets as in Part A. Rank these planets in order of radius, from largest to smallest. Rank from largest radius to smallest radius. To rank items as equivalent, overlap them.
HAT-P32b, COROT-14b, Jupiter, Earth, Kepler 10b
The solar system has two types of planets, terrestrial and jovian. According to the nebular theory, why did terrestrial planets form in the inner solar system and jovian planets in the outer solar system?
Ices condensed only in the outer solar system, where some icy planetesimals grew large enough to attract gas from the nebula, while only metal and rock condensed in the inner solar system, making terrestrial planets.
As you saw in Part A, Io's elliptical orbit is necessary to its tidal heating. This elliptical orbit, in turn, is a result of the orbital resonance among Io, Europa, and Ganymede. This orbital resonance causes Io to have a more elliptical orbit than it would otherwise, because __________.
Io, Europa and Ganymede periodically return to the same orbital positions, creating the same gravitational tugs
Consider the elliptical orbit of a comet around the Sun. Where in its orbit does it have the largest amount of total orbital energy?
It always has the same total orbital energy.
According to our theory of solar system formation, what three major changes occurred in the solar nebula as it shrank in size?
It got hotter, its rate of rotation increased, and it flattened into a disk.
Which of the following best explains why Kepler 10b is called a "super-Earth"?
It has similar composition to Earth, but is more massive.
What do we mean by the frost line when we discuss the formation of planets in the solar nebula?
It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense.
Suppose that, overall, your 3-year transit program detects planets orbiting about 1% of the stars that you are monitoring. What should you conclude?
It is likely that most stars in your survey are orbited by planets.
According to the nebular theory, how did the Kuiper belt form?
It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet.
What happens to the energy that the ground absorbs in the form of visible sunlight?
It is returned upward in the form of infrared light.
On a cloudless day, what happens to most of the visible light headed toward Earth?
It reaches Earth's surface, where some is reflected and some is absorbed.
Which planet has a ring system?
Jupiter, Uranus, Saturn, Neptune
Consider the same set of planets as in Part A, but without Earth. Rank these planets in order of average density, from highest to lowest. Rank from highest density to lowest density. To rank items as equivalent, overlap them.
Kepler 10b, COROT-14b, Jupiter, HAT-P32b
We expect a scientific theory to be able to make predictions that can be tested. Which of the following is a prediction of the nebular theory that has been verified by observations?
Many stars should have planets.
Which of the following lists the planets of our solar system in the correct order from closest to farthest from the Sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Compare lead at 500 K with gold that is 400 K. Which of the following statements apply to the infrared radiation those substances emit? Assume that the sizes and shapes of the lead and gold samples are identical and opaque to radiation. Why are astronauts weightless in the Space Station?
One cannot tell from the information provided, since the infrared spectrum from the lead sample will be very different from the spectrum of the gold sample.
Which of the following is an example of reflection or scattering?
Red light hits a red sweatshirt
Assume that the light curve shown below represents data from repeated transits by one planet in your sample. Which of the numbered points represents the time when the planet is directly in front of its star as viewed from Earth?
Reference HW 5 (Question 16)for picture 3