Deck 3: The Solar System

Question 1

Newton's modification of Kepler's Third Law lets us measure the mass of the Sun.

Answer 1

True

Question 2

Kepler based his theories on the precise planetary observations of Tycho Brahe.

Answer 2

True

Question 3

Mercury, with a higher eccentricity orbit, should change its orbital speed more than do Venus or Earth.

Answer 3

True

Question 4

Galileo's observations of the entire phase cycle of Venus proved that Ptolemy's epicycles could not be correct in keeping Venus between us and the Sun.

Question 5

Galileo's observations of sunspots proved the Sun was rotating, like the Earth.

Question 6

It the mass of a body were doubled, its gravity would become 4 times stronger.

Question 7

Transits of Venus were critical in early determinations of the AU.

Question 8

Like the Sun and the Moon, the stars appear to move from west to east from one day to the next.

Question 9

All the jovian planets lie beyond the asteroid belt.

Question 10

Newton's Laws completely replaced the incorrect work of Kepler.

Question 11

The parallax shift of a star would be greater if viewed from Mars than from Earth.

Question 12

Kepler found the orbits of planets are ellipses, not circles.

Question 13

The eccentricity of a perfectly circular orbit is 1.

Question 14

Like the Sun and the Moon, the planets appear to move from west to east from one day to the next.

Question 15

Newton's Law of Gravity would explain why Saturn, so far from the Sun, moves so slowly across the sky.

Question 16

A planet (or comet) will speed up as it approaches the Sun.

Question 17

Kepler determined the shape of each planet's orbit by triangulation from different points on Earth's orbit, using observations made at many different times of the year.

Question 18

When a planet retrogrades, it appears to move westward.

Question 19

The orbits of most of the planets in our solar system have eccentricities close to zero.

Question 20

According to Newton's second law, if you double the force acting on a body, the acceleration will double.

Question 21

Scientists today do not accept the Ptolemaic model because

A) it is ancient history.
B) it was too complicated, compared to Copernicus' heliocentric model.
C) it has been shown that Ptolemy faked his data.
D) it had no explanation for retrograde motion.

Question 22

The most accurate Greek attempt to explain planetary motion was the model of

A) Aristotle.
B) Pythagoras.
C) Hipparchus.
D) Ptolemy.
E) Erastothenes.

Question 23

On which of these assumptions do Ptolemy and Copernicus agree?

A) The Earth must be the center of all motion in the Cosmos.
B) All orbits must be perfect circles.
C) The Sun was bigger than the Earth.
D) Venus must always stay between us and the Sun.
E) The Sun must orbit us, but the planets do orbit the Sun.

Question 24

The Ptolemaic model of the universe

A) explained and predicted the motions of the planets with deferents and epicycles.
B) is the basis of our modern cosmology.
C) could not account for the stellar parallax observed by Hipparchus.
D) describes the orbits of the planets as being ellipses, not circles.
E) always kept Mars and Mercury between the Earth and Sun.

Question 25

Which of the following is a contribution to astronomy made by Galileo?

A) The astronomical telescope can show us far more detail than the eye can.
B) Jupiter has four moons orbiting it.
C) The Moon has craters, mountain, valleys, and dark flat areas on its surface.
D) Venus appears almost fully lit when it lies on the far side of the Sun.
E) all of the above

Question 26

Which of these was NOT seen telescopically by Galileo?

A) Sunspots
B) Venus' phase cycle
C) Four moons around Jupiter
D) Stellar parallax
E) Craters and mare on the Moon

Question 27

Occam's Razor

A) divides the inner planets from the outer planets.
B) tells scientists to use the simplest model, all other things being equal.
C) is the term that describes how thin the rings of the Jovian planets are.
D) describes how a planet's orbital period and distance from the Sun are related.
E) is the tool that Copernicus used to shave.

Question 28

According to Copernicus, the retrograde motion for Mars must occur

A) at inferior conjunction, when Mars laps the Earth and passes between us and the Sun.
B) at superior conjunction, when Mars lies on the far side of the Sun.
C) at quadrature, when Mars lies exactly 90 degrees east or west of the Sun.
D) at greatest elongation, when Mars can get up to 47 degrees from the Sun.
E) at opposition, when the Earth overtakes Mars and passes between Mars and the Sun.

Question 29

Which of these observations of Galileo refuted Ptolemy's epicycles?

A) The complete cycle of Venus' phases
B) The rotation of sunspots across the Sun's surface
C) The revolution of Jupiter's moons around it
D) The craters on the Moon
E) The visibility of many more stars with the telescope

Question 30

Of all the terrestrial planets, Mercury's orbit is most eccentric and tilted most above the ecliptic.

Question 31

A fatal flaw with Ptolemy's model is its inability to predict the observed phases of

A) the Sun during an eclipse.
B) the Moon in its monthly cycle.
C) Mercury and Venus.
D) Mars and Jupiter.
E) Jupiter and Saturn.

Question 32

Which of the following describes parallax?

A) It is best measured over exactly one year intervals.
B) It is inversely proportional to the distance to the star.
C) It was first observed by Galileo with his new telescope.
D) It is only applicable to objects within the solar system.
E) It is more accurate as the distances to objects becomes greater.

Question 33

To fully describe the apparent motion of the planets in the sky, Ptolemy's model invoked

A) ellipses.
B) constant speeds.
C) a heliocentric view.
D) epicycles.
E) Occam's Razor.

Question 34

Due to their great masses, all four jovian worlds are much denser than the Earth.

Question 35

Which of the statements below is part of both the Ptolemaic and Copernican models?

A) The Earth orbits the Sun once a year.
B) The Sun lies in the center of the Cosmos.
C) The Moon orbits the Earth once a month.
D) Epicycles are needed to explain retrograde motion of the planets.
E) Venus' epicycle must always lie between us and the Sun.

Question 36

A star with a large parallax

A) is at a great distance from Earth.
B) is moving at a great speed with respect to Earth.
C) is at a short distance from Earth.
D) is moving at a slow speed with respect to Earth.
E) is not moving with respect to Earth.

Question 37

All the terrestrial planets lie inside the asteroid belt.

Question 38

Scientists today do not accept the Ptolemaic model because

A) it is ancient history.
B) it was too complicated, compared to Copernicus' heliocentric model.
C) it has been shown that Ptolemy faked his data.
D) it had no explanation for retrograde motion.
E) the work of Tycho and Kepler showed the heliocentric model was more accurate.

Question 39

Which of the following was NOT a contribution of Galileo to astronomy?

A) Sunspots showed the Sun was rotating on its axis, like the Earth does.
B) The four moons of Jupiter are a model for the solar system motions in general.
C) The phases of Venus prove it orbits completely around the Sun.
D) The changing appearance of Saturn's rings corresponds to our seasons.
E) The craters and mountains of the Moon prove it a world in its own right.

Question 40

The heliocentric model was actually first proposed by

A) Aristotle.
B) Archimedes.
C) Aristarchus.
D) Alexander the Great.
E) Hipparchus.

Question 41

Tycho Brahe's contribution to Kepler's Laws of Planetary Motion were

A) his detailed and accurate observations of the planet's position.
B) his observations of Jupiter's moons.
C) a mathematical explanation of epicycles.
D) a precise lunar calendar.
E) the correct explanation of lunar phases.

Question 42

Jupiter lies about 5 AU from the Sun, so at its distance

A) the Sun's gravity is just as strong as it is here at Earth.
B) the Sun's gravity must be five times stronger to hold massive Jupiter in orbit.
C) the Sun's gravity is five times weaker there than at one AU distance.
D) the Sun's gravity is 25 times weaker than its pull on the Earth.
E) the Sun's gravity is so weak that ultimately Jupiter will escape the solar system.

Question 43

Upon which point do Copernicus and Kepler disagree?

A) The Moon orbits the Earth.
B) The Earth orbits the Sun.
C) Retrograde motion occurs when one planet overtakes another.
D) The orbits of the planets are ellipses, with one focus at the Sun.
E) Venus will appear as a crescent when she retrogrades between us and the Sun.

Question 44

Galileo found the rotation period of the Sun was approximately

A) a day.
B) a week.
C) a month.
D) three months.
E) a year.

Question 45

The planet's orbital period is

A) the time it takes it to rotate and have the same face toward us again.
B) the time it takes to return to the same location in the sky, relative to the Sun.
C) the time it takes for a satellite to orbit it.
D) the time it takes for it to retrograde back to the same position as we pass it.
E) the time its magnetic field takes to spin once.

Question 46

Which concept was NOT a part of Kepler's Laws of Planetary Motion?

A) All planetary orbits are ellipses.
B) The square of the planet's period is equal to the cube of its average distance.
C) A planet must move fastest in its orbit at perihelion.
D) Epicycles are needed to explain the varying brightnesses of the planets.

Question 47

Which of these was a contribution of Newton to astronomy?

A) Artificial satellites could be put into orbit about the Earth.
B) The Sun's gravity is greatest on a planet at perihelion, so the planet must speed up.
C) The Moon pulls as strongly on us as we do on it.
D) His differential calculus lets us calculate planetary motions more accurately.
E) All of these were due to Newton's work.

Question 48

It took two centuries for the Copernican model to replaced the Ptolemaic model because

A) in Copernicus' time, there were no telescopes.
B) the Church wouldn't let anyone talk about Copernicus' model for 200 years.
C) there was no scientific evidence to support either model until Galileo made his observations.
D) the Ptolemaic model was simpler and more aesthetically pleasing.
E) the Copernican model required complicated new terms to explain it correctly.

Question 49

Given that the planet orbiting the nearby star 51 Pegasi is about 20X larger than the Earth, but 400X more massive, on that world you would weigh

A) the same as you do here.
B) twice as much as you do here.
C) half as much as you do here.
D) 20X more that you do here.
E) 400X more than you do here.

Question 50

The Law of Universal Gravitation was developed by

A) Kepler.
B) Galileo.
C) Newton.
D) Copernicus.
E) Einstein.

Question 51

According to Kepler's third law, the square of the planet's period in years is

A) equal to its perihelion distance from the Sun in AU.
B) inversely proportional to its mass in kilograms.
C) equal to the fourth power of its average temperature in degrees Kelvin.
D) proportional to the cube of its semimajor axis in AU.
E) equal to the square of its aphelion distance in AU.

Question 52

A circular orbit would have an eccentricity of

A) 0.
B) between 0 and 0.5.
C) between 0.5 and 1.
D) exactly 1.0.
E) infinity.

Question 53

What contribution to astronomy was made by Tycho Brahe?

A) The planets' orbits around the Sun are ellipses, not circles.
B) The Earth is not the center of the Universe.
C) His observations of planetary motion with great accuracy proved circular orbits could not work.
D) His telescope revealed the moons of Jupiter before Galileo noted them.
E) Retrograde motion must be explained by epicycles larger than those of Ptolemy.

Question 54

How much stronger is the gravitational pull of the Sun on Earth, at 1 AU, than it is on Saturn at 10 AU?

A) 5X
B) 10X
C) 25X
D) 100X
E) 250X

Question 55

What does Kepler's third law imply about planetary motion?

A) All planets orbit the Sun at the same speed.
B) Planets closer to the Sun orbit at a slower speed than planets further from the Sun.
C) Planets further from the Sun orbit at a slower speed than planets closer to the Sun.
D) Planets further from the Sun orbit at a faster speed than planets closer to the Sun.
E) This law implies nothing about a planet's motion.

Question 56

The force of gravity varies with the

A) product of the two masses.
B) inverse of the distance separating the two bodies.
C) inverse square of the distance separating the two bodies.
D) Both A and B are correct.
E) Both A and C are correct.

Question 57

A planet whose distance from the Sun is 3 AU would have an orbital period of how many Earth-years?

A) 3
B) $\sqrt { 27 }$
C) $\sqrt { 3 }$
D) 9
E) 81

Question 58

Kepler's first law worked, where Copernicus' original heliocentric model failed, because Kepler described the orbits as

A) elliptical, not circular.
B) much larger than Copernicus had envisioned.
C) around the Sun, not the Earth.
D) being on equants instead of epicycles.
E) complex, with epicycles to account for retrograde motions.

Question 59

The force of gravity between two objects

A) increases with the masses of the bodies, but decreases with their separations.
B) increases with the masses of the bodies, but decreases with the square of the distances between them.
C) increases with the square of their masses, but decreases with the cube of their periods of orbit about the Sun.
D) depends on the density, not the mass of the bodies.
E) depends on the temperature, density, and size of the bodies.

Question 60

According to Newton's Law of Universal Gravitation, if the Moon were three times further from Earth, the force by Earth on the Moon would

A) increase by a factor of 3.
B) decrease by a factor of 3.
C) increase by a factor of 9.
D) decrease by a factor of 9.
E) stay the same.

Question 61

Mercury's most unusual orbital feature, as compared to the other planets, is

A) the size of its orbit.
B) the shape of its orbit.
C) its orbital period.
D) the size of the planet.
E) that it has no moons.

Question 62

The average density of each planet in the solar system is determined by taking its mass and dividing that by its

A) radius.
B) diameter.
C) surface area.
D) radius squared.
E) volume.

Question 63

Which statement about the motion of the planets is INCORRECT?

A) Most orbit above the Sun's equator.
B) All revolutions of major planets are counterclockwise.
C) The orbits of most planets are almost circular, with low eccentricities.
D) Most planets move in the Earth's equatorial plane.
E) Most planets rotate in the counterclockwise direction when viewed from the North.

Question 64

How do the densities of the jovian and terrestrial planets compare?

A) Made from the same solar nebula, they are all similar.
B) More massive jovians all have high densities, compared to the tiny terrestrials.
C) All terrestrials are more dense than any of the jovians.
D) The closer a planet lies to the Sun, the less its density.
E) No real pattern here; densities vary greatly and are very individual to each world.

Question 65

The plane in which almost all planets orbit the Sun is called the

A) equator of the solar system.
B) ecliptic.
C) equant.
D) node.
E) galactic plane.

Question 66

Galileo's observations of the phases of ________ could not be explained by Ptolemy's epicyclic model.

Question 67

What aspects of the planets orbits are nearly the same for most planets?

A) Orbital period and shape
B) Shape and tilt from the ecliptic
C) Shape and distance from the Sun
D) Orbital period and distance from the Sun
E) Tilt from the ecliptic and distance from the Sun

Question 68

During the eighteenth and nineteenth centuries, attempts to precisely measure the astronomical unit relied largely on rare

A) total solar eclipses.
B) transits of the inferior planets across the Sun.
C) passages of comets close to the Earth.
D) maximum elongations of Venus.
E) oppositions of Mars.

Question 69

What is TRUE about solar system densities?

A) The denser planets lie closer to the Sun.
B) In differentiated bodies, the denser materials lie near their surfaces.
C) The asteroids all have about the same density.
D) Saturn has the same density as water.
E) Planetary density increases with increasing distance from the Sun.

Question 70

In order to determine the mass of a planet by applying Newton's laws of motion and gravity, the planet must have

A) rings.
B) moons.
C) a solid surface.
D) a known size and distance from Earth.
E) planets further from the Sun than itself.

Question 71

How does Newton's Universal Law of Gravitation explain Kepler's laws?

A) Universal gravitation implies that the orbits of the planets must be elliptical (Kepler's first law).
B) Universal gravitation implies that the planets will sweep out equal areas in equal times (Kepler's second law).
C) Universal gravitation implies that the planets further from the Sun will move more slowly than the planets closer to the Sun (Kepler's third law).
D) Universal gravitation implies that when a planet is closer to the Sun in its orbit, it will move faster than when it is farther from the Sun (Kepler's second law).
E) Both C and D are correct.

Question 72

Galileo's discovery of four moons orbiting ________ provided new support for the ideas of Copernicus.

Question 73

Planets do not move on a straight line. According to Newton's First Law of Motion, that means that there must be an outside ________ acting on them.

Question 74

According to Newton's second law, when the same force acts on two bodies, the body with the larger mass will have the ________ acceleration.

Question 75

Because he failed to observe stellar ________, Aristotle wrongly concluded we could not be in orbit around the Sun.

Question 76

To explain retrograde motion as well as changes in planetary brightness, Ptolemy's model used ________.

Question 77

Today we rely largely on what technique to precisely measure distances in the solar system?

A) Transits of Venus across the Sun
B) Radar echo timings
C) Measurement of stellar parallaxes.
D) Timings of the eclipses of its moons by Jupiter's shadow
E) Precise measurements of length of the year with atomic clocks

Question 78

Masses of the planets are easiest to determine if

A) they are terrestrial and the extra size of the planet's disk can be measured.
B) they are jovian and their oblateness can be found.
C) they have natural satellites whose motions can be precisely measured.
D) they are dense and easily deflect the path of passing spacecraft.
E) they move rapidly and their periods are easily measured.

Question 79

Planetary orbits

A) are evenly spaced throughout the solar system.
B) are highly inclined to the ecliptic.
C) are almost circular, with low eccentricities.
D) have the Sun at their exact center.
E) are spaced more closely together as they get further from the Sun.

Question 80

Which of the following are the jovian planets?

A) Jupiter, Saturn, Uranus, Neptune, and Pluto
B) Only Jupiter
C) Only Jupiter and Saturn
D) Jupiter, Saturn, Uranus, and Neptune only
E) Everything past Mars and the asteroid belt