Exam 2 Preview
Which of the following planets or moons has an atmosphere with about 90 times the surface pressure of Earth's. a. Mercury b. Venus c. Mars d. Titan
b. Venus
Mars space probes
1964 Mariner 4- flyby, first picture 1971 Mariner 9- orbiter 1975 Viking 1&2- orbiters and landers 1996 Mars Global Surveyor- orbiter 2003 Spirit and Opportunity- rovers 2012 Curiosity- rover 2020- Curiosity II planned
Venus space probes
1970 Venera 7- the first lander (of any planet) 1975 Venera 9- the first pictures from the surface 1978 Pioneer- orbiter, the first radar map of the surface 1989 Magellan- orbiter, high resolution topographic maps 2010 Akatsuki- orbiter, rescued from failure and there now
Mercury space probes
1974 Mariner 10- multi-flyby 2004 Messenger- orbiter 2018 bepiColombo- orbiter
My Very Eager Mother Just Served Us Noodles
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune
Which of these planets is the farthest from the Sun? a. Mars b. Mercury c. Venus d. Earth
a. Mars
Which of the following planets can be said to have almost no atmosphere? a. Mercury b. Venus c. Earth d. Mars
a. Mercury
As viewed from the star Polaris, Venus a. rotates clockwise and goes around the Sun counter-clockwise. b. rotates counter-clockwise and goes around the Sun clockwise. c. rotates clockwise and goes around the Sun clockwise. d. rotates counter-clockwise and goes around the Sun counter-clockwise. e. does not rotate at all.
a. rotates clockwise and goes around the Sun counter-clockwise.
If you are told that an object that weighs 20 Newtons is raised a distance of 10 meters, you know that. a. the force of gravity on the object is 20 Newtons. b. the mass of the object is 20 Newtons. c. the force of gravity on the object is 10 meters. d. the mass of the object is 10 meters. e. the acceleration of the object is 200 kilogram-meters.
a. the force of gravity on the object is 20 Newtons.
Suppose that you drop two objects from the same height at the same time. Both objects are heavy enough to be unaffected by air resistance. If one object is twice as heavy as the other, Aristotle would predict that a. the heavier object would hit the ground long before the lighter one. b. the lighter object would hit the ground long before the heavier one. c. both objects would hit the ground at the same time.
a. the heavier object would hit the ground long before the lighter one.
Suppose that you try to lift an object by exerting an upward force of 5 Newtons on it. If gravity exerts a force of 20 Newtons downward on the object, what is the total force on the object? a. 15 Newtons upward. b. 15 Newtons downward. c. 5 Newtons upward. d. 5 Newtons downward. e. 25 Newtons downward.
b. 15 Newtons downward.
The first successful soft landing on the Moon was Surveyor 1 in a. 1958. b. 1966. c. 1969. d. 1972. e. 1974.
b. 1966.
Which of the following types of objects include things that could reasonably be described as "flying rocks" or, for the larger ones, "flying mountains?" a. Comets. b. Asteroids. c. Kuiper Belt Objects. d. Jovian Planets.
b. Asteroids.
Which of the following objects has no magnetic field at all? a. Mercury b. Earth's Moon c. Mars d. Jupiter e. Saturn
b. Earth's Moon
A planet that is following Kepler's Laws, accelerates a. in the direction of the planets motion. b. toward the Sun. c. away from the Sun. d. between the direction of the planets motion and the direction from the planet to the Sun. e. opposite to the direction of the planets motion.
b. toward the Sun.
The Law of Inertia says that if an object is not acted on by any outside force, its acceleration a. will always be a constant. b. will always be zero. c. will be zero if the object is at rest and not zero if the object is moving. d. can have any value at all.
b. will always be zero.
The average radius of the Earth's orbit is a. 0.1 au. b. 0.01 au. c. 1.0 au. d. 2.0 au. e. 5 au.
c. 1.0 au.
What total force will cause an object with a mass of 1kg to gain 5 meters per second every second? a. 1 Newton. b. 9.8 Newtons. c. 5 Newtons. d. 10 Newtons. e. 2.5 Newtons.
c. 5 Newtons. F= ma F= 1 X 5
The density of water is 1000kg/m³, the density of rock is about 3000kg/m³, and the density of iron is 7800kg/m³. Which of the following densities is closest to the average density of the Earth? a. 700kg/m³ b. 1300kg/m³ c. 5200kg/m³ d. 3900kg/m³ e. 10,000kg/m³
c. 5200kg/m³
The current model for the way that planets acquire magnetic fields requires which of the following combinations of things? a. rotation and an iron core. b. only an iron core. c. rotation and a core that contains a liquid electrical conductor. d. only a core that contains a liquid electrical conductor. e. rotation and a core that contains liquid iron.
c. rotation and a core that contains a liquid electrical conductor.
A full cycle of day and night on Mars is called a `sol.' In terms of 24 hour Earth days, a Martian sol is a. about 27 Earth days. b. slightly shorter than one Earth day. c. slightly longer than one Earth day. d. about 687 Earth days. e. about 11 hours.
c. slightly longer than one Earth day.
Since the last Apollo mission to the Moon and the last Soviet LUNA sample-return mission a. there have been no spacecraft sent there at all. b. spacecraft began to be sent there again by 1980. c. spacecraft began to be sent there again by 1994. d. spacecraft began to be sent there again starting in 2003. e. spacecraft began to be sent there again starting in 2007.
c. spacecraft began to be sent there again by 1994.
When Newton calculated the magnitude of the acceleration of Earth's Moon relative to the Earth, and compared it to the acceleration of falling objects on the surface of the Earth, he found that a. the accelerations were the same. b. the Moon's acceleration was larger. c. the Moon's acceleration was smaller.
c. the Moon's acceleration was smaller.
For an object that is moving along a straight path, the acceleration is a. zero b.the distance the object travels divided by the time it takes. c. the change in the object's speed divided by the time it takes. d. the time the object is moving divided by the distance it travels during that time. e. the time the object is moving divided by the change in its speed during that time.
c. the change in the object's speed divided by the time it takes.
Viking 1 and 2 were sent to explore a. the planet Venus. b. Earth's Moon. c. the planet Mars. d. the planet Jupiter. e. the planet Neptune.
c. the planet Mars.
The Soviet Union had a secret program to put the first human on the Moon. This program a. never got beyond the planning stage. b. built a Moon rocket, but never test fired it. c. successfully test launched a Moon rocket that worked but was cancelled by the Politburo. d. test launched their Moon Rocket several times, but it blew up each time.
d. test launched their Moon Rocket several times, but it blew up each time.
In Newton's theory of gravity, everything is attracted a. only to the Sun. b. only to the center of the Earth. c. only to massive heavenly objects such as the Sun, Moon, planets, and the Earth. d. to every other object in the universe. e. to the center of the universe.
d. to every other object in the universe.
An ion rocket engine produces 50 Newtons of thrust. What acceleration can it give to a space probe with a mass of 10,000kg? a. 5 m/s². b. 5000 m/s². c. 0.5 m/s². d. 0.05 m/s². e. 0.005 m/s².
e. 0.005 m/s².
Why couldn't we just fly a Space Shuttle to the Moon for at least a fly-by? a. The Space Shuttle needed the support of Earth's atmosphere. b. All of the Space Shuttle flights were reserved for other things. c. We had already been to the Moon. d. The Space Shuttle would not have enough fuel to make it back to Earth. e. The Space Shuttle did not have enough fuel to reach escape velocity.
e. The Space Shuttle did not have enough fuel to reach escape velocity.
Which of the following planets has no magnetic field of any kind? a. Mercury b. Venus c. Mars d. Jupiter e. Saturn
b. Venus
A solar sail is a large sheet of light-reflecting plastic spread on an extremely low-mass framework and attached to a spacecraft. Sunlight exerts a force on the sail and moves the spacecraft. Suppose the spacecraft has a total mass of 5000kg (including the sail) and sunlight exerts a total force of 5N on the sail. What will be the acceleration of the spacecraft? a. 0.001m/s². b. 5m/s². c. 0.05m/s². d. 5000m/s². e. 25,000m/s².
a. 0.001m/s².
The first space probes to land on another planet were from the a. Russian Venera series. b. The US Pioneer series. c. The European Venus Express series. d. The Viking series. e. The Voyager series.
a. Russian Venera series.
Which of the following planets has no moons at all? a. Venus b. Earth c. Mars d. Jupiter e. Neptune
a. Venus
The ancient greeks thought that a. a heavy object should fall faster than a lighter object because the heavy object is pulled down with more force. b. a light object should fall faster than a heavier object because the lighter object offers less resistance to motion. c. a heavy object should fall at the same speed as a lighter object because the heavier object feels more force but the lighter object offers less resistance to motion.
a. a heavy object should fall faster than a lighter object because the heavy object is pulled down with more force.
Space probes often use gravitational slingshot maneuvers. The main purpose of these maneuvers is to a. change the direction and speed of the probe without using rockets. b. launch probes from Earth orbit without using rockets. c. see more planets in a single trip. d. arrive at the destination at the right time.
a. change the direction and speed of the probe without using rockets.
The magnetic field of Mars is a. essentially zero. b. about 1% of the Earth's magnetic field. c. Similar in intensity to the Earth's magnetic field. d. about 10 times the intensity of the Earth's magnetic field. e. about 100 times the intensity of the Earth;s magnetic field.
a. essentially zero.
The Lunar Maria are thought to have been caused by ancient a. lava flows from large impacts. b. oceans of water that have since evaporated. c. bombardment by charged particles from the Sun. d. dust storms in an atmosphere that has now vanished.
a. lava flows from large impacts.
The observed magnetic field of Mercury is surprising because it was expected to have a. no magnetic field at all because it rotates so slowly. b. no magnetic field at all because its density indicates only a small iron core. c. a much larger magnetic field because of its huge iron core. d. a magnetic field similar to Earth's because it is a terrestrial planet.
a. no magnetic field at all because it rotates so slowly.
It is expected that a normal terrestrial planet, with no accidental encounters that could add or subtract moons, should have a. no moon b. just one moon c. a family of moons, all orbiting in the plane of the planets equator
a. no moon
It is currently thought that moons typically do not form near a. Jovian planets such as Jupiter and Saturn. b. Terrestrial planets such as Earth and Mars. c. Any planets of isolated stars. d. Any planets of binary star systems.
b. Terrestrial planets such as Earth and Mars.
Why don't we just shoot all of our really nasty waste products into the Sun where they could not possibly bother anyone? a. One person's trash is another person's treasure. Maybe someone will buy it from us. b. The Sun is actually the hardest part of the Solar System to get to from here. c. If we drop our trash out of orbit, it might end up anywhere. d. It might bounce back at us. e. The Space Shuttle is not flying anymore and the Russians do not want to cart our trash.
b. The Sun is actually the hardest part of the Solar System to get to from here.
A book, weighing 10 Newtons, sits on a table. Which of the following pairs of forces is an action-reaction pair? a. The force of gravity on the book and the force that the table exerts on the book. b. The force that the book exerts on the table and the force that the table exerts on the book. c. The force of gravity on the book and the force that the book exerts on the table. d. The force of gravity on the book and the force of gravity on the table. e. The force that the book exerts on the table and the force of gravity on the table.
b. The force that the book exerts on the table and the force that the table exerts on the book.
You are standing in an elevator that is accelerating upward at 1m/s². Which of the following pairs of forces is an action-reaction pair that have to be exactly equal and opposite to each other? a. The force of gravity on you and the force that the floor of the elevator exerts on you. b. The force that the floor of the elevator exerts on you and the force that you exert on the floor of the elevator. c. The force of gravity on you and the force that you exert on the floor of the elevator. d. None of these pairs because acceleration requires an unbalanced force.
b. The force that the floor of the elevator exerts on you and the force that you exert on the floor of the elevator.
Water ice can be found on all but one of these planets. Which one has no ice? a. Mercury b. Venus c. Earth d. Mars
b. Venus
A lunar crater is best described as a. any large flat area that is lower than the surrounding area. b. a circular ring wall surrounding a flat area. c. a mountain in the center of a flat area. d. a large, deep hole in the Moon.
b. a circular ring wall surrounding a flat area.
In comparison to Kepler's Laws of Planetary Motion, Newton's theory of Universal Gravitation predicted a. exactly the same motions. b. almost the same motions but with corrections. c. a completely different set of motions. d. the same motions interpreted differently.
b. almost the same motions but with corrections.
On Earth, you might find a temperature of 59°F on a Spring or Fall day in the temperate zone. On Mars, you might expect that temperature a. only at the poles. b. at noon near the equator. c. nowhere on Mars. d. almost anywhere on Mars when the Sun is shining.
b. at noon near the equator.
When a space probe uses a gravitational slingshot maneuver, it a. reverses gravity to repel the probe. b. comes close to a planet to change the probe's speed and direction. c. uses a counterweight on the end of a long cable or tether to change its speed and direction. d. converts its rotational motion into forward motion.
b. comes close to a planet to change the probe's speed and direction.
Which of the following objects would be most likely to have a long elliptical orbit that takes it from far outside the orbit of Mars to a close approach to the Sun? a. asteroid b. comet c. planet
b. comet
The discovery that there is water ice on the Moon has motivated many nations to launch Moon missions because it a. indicates that life might have originated on the Moon. b. could make a Moon base possible. c. complicates the already difficult problem of explaining how the Moon formed. d. could be mined and sent back to the Earth.
b. could make a Moon base possible.
Apollo 11 made the first a. landing on the Moon by a spacecraft. b. crewed landing on the Moon. c. crewed orbit of the Moon. d. test of docking procedures in lunar orbit.
b. crewed landing on the Moon.
Freely falling objects with different masses fall with the same acceleration because a. they have the same amount of inertia. b. gravity exerts more force on the more massive object. c. gravity acts with the same force on both objects. d. gravity acts with less force on the more massive object. e. there is no air resistance.
b. gravity exerts more force on the more massive object.
A model in which the Moon forms from the same rotating cloud of gas and dust as the Earth would predict that the Moon's orbit should be a. in the plane of the ecliptic. b. in the plane of the Earth's equator. c. perpendicular to the plane of the Earth's equator. d. somewhat tilted relative to the plane of the Earth's equator.
b. in the plane of the Earth's equator.
The Earth's Moon a. is 1/25 the size of the Earth, which is a normal size for a moon. b. is 1/4 the size of the Earth, which is unusually large for a moon. c. is 1/500 the size of the Earth, which is unusually small for a moon. d. is 1/4 the size of the Earth, which is a normal size for a moon. e. is 1/25 the size of the Earth, which is small for a moon.
b. is 1/4 the size of the Earth, which is unusually large for a moon.
The gravitational attraction of the Earth for other objects, a. is the same no matter where those objects are. b. is smaller for objects farther from the Earth but never vanishes entirely. c. extends only as far as the Earth's atmosphere and vanishes for objects like an orbiting space station. d. is larger for objects farther from the Earth.
b. is smaller for objects farther from the Earth but never vanishes entirely.
Compared to the rest of the Lunar surface, the Lunar Maria are a. higher and younger. b. lower and younger. c. higher and older. d. lower and older. e. at about the same level and age.
b. lower and younger.
When the rocket engine in a spaceship stops firing, the spaceship keeps moving because a. the force of its inertia pushes it. b. no force stops it. c. it is pointed at the front and has fins at the back. d. the force exerted by the rocket engine earlier keeps acting on it.
b. no force stops it.
The phase diagram for water is presented on a graph with axes for temperature and a. mass density b. pressure c. volume d. physical state
b. pressure
At present (within the last few hundred years) the orbit of the Earth around the Sun is a. exactly circular so that the intensity of sunlight never changes. b. slightly elliptical so that.the intensity of sunlight varies by 6 percent. c. very elliptical so that.the intensity of sunlight varies by 40 percent. d. slightly elliptical but not enough to change the intensity of sunlight by even 1 percent. e. hyperbolic so that Earth will leave the Solar System and never return.
b. slightly elliptical so that the intensity of sunlight varies by 6 percent.
An astronomical unit is defined to be a. the average distance from the Earth to the Moon. b. the average distance from the Earth to the Sun. c. the distance to a star that shows one arc-second of parallax shift. d. the distance that light travels in a year. e. the average amount of time it takes the Earth to complete one orbit around the Sun.
b. the average distance from the Earth to the Sun.
If you are told that a 20 kilogram object is raised by 10 meters, you know that a. the force of gravity on the object is 20 kilograms. b. the mass of the object is 20 kilograms. c. the force of gravity on the object is 10 meters. d. the mass of the object is 10 meters. e. the acceleration of the object is 200 kilogram-meters.
b. the mass of the object is 20 kilograms.
The Moon rotates on its axis so that it always keeps a. the same side (its dark side) pointed away from the Sun. b. the same side (its far side) pointed away from the Earth. c. the same side toward a particular distant star.
b. the same side (its far side) pointed away from the Earth.
The Moon rotates on its axis so that it always keeps the same side a. towards the Sun. b. toward the Earth. c. toward a particular distant star.
b. toward the Earth.
Which of the following planets or moons has an atmosphere whose temperature and pressure permit all three forms of water? a. Mercury b. Venus c. Earth d. Mars e. Titan
c. Earth
Galileo predicted that dropping a wooden ball and an iron ball at exactly the same time would result in them hitting the ground at the same time, so long as air friction was negligible. When he actually did the experiment, the balls hit the ground very close together, but sometimes the wooden ball hit first and sometimes the iron one hit first. If we repeat his experiment today, we find exactly the same thing. Which of the following conclusions is appropriate? a. Galileo's theory was disproven since his prediction did not correspond to observation. b. Galileo did not really do the experiment. c. Galileo really did the experiment.
c. Galileo really did the experiment.
Galileo predicted that dropping a wooden ball and an iron ball at exactly the same time would result in them hitting the ground at the same time, so long as air friction was negligible. When he actually did the experiment, the balls hit the ground very close together, but sometimes the wooden ball hit first and sometimes the iron one hit first. If we repeat his experiment today, we find exactly the same thing. Which of the following conclusions is appropriate? a. Galileo's theory was disproven since his prediction did not exactly correspond to observation. b. Galileo did not really do the experiment. c. Galileo's theory was not disproven because the slight differences can be explained by defects in the experiment.
c. Galileo's theory was not disproven because the slight differences can be explained by defects in the experiment.
Which of the following planets has a moon that rises in the West? a. Venus b. Earth c. Mars d. Mercury
c. Mars
Which of these planets has a solar day that is very close to an Earth day in length? a. Mercury b. Venus c. Mars d. Jupiter e. Saturn
c. Mars
Which of these Mars rovers has been operating on the surface of Mars for fourteen years so far (as of 2018)? a. Pathfinder b. Spirit c. Opportunity d. Curiosity e. Surveyor
c. Opportunity
The capture theory, in which our Moon forms separately and is captured by the Earth, became popular when computer models showed that such a capture would have been possible. a. The capture theory is still the accepted model for the formation of the Moon. b. The capture theory was dropped partly because it predicts that the Moon should orbit in the plane of the Earth's equator and it does not. c. The capture theory was dropped partlybecause it predicts that the Moon should have hydrated rocks and it does not. d. The capture theory was dropped partly because it predicts that the Moon should not have a large iron core and it does.
c. The capture theory was dropped partly because it predicts that the Moon should have hydrated rocks and it does not.
Mars has a. almost no atmosphere. b. an atmosphere of carbon dioxide with about 90 times the surface pressure of Earth's. c. an atmosphere of carbon dioxide with about 1% the surface pressure of Earth's. d. an atmosphere whose temperature and pressure permit all three forms of water. e. an atmosphere whose temperature and pressure permit all three forms of methane.
c. an atmosphere of carbon dioxide with about 1% the surface pressure of Earth's.
On the present surface of Mars, water has been confirmed to exist a. as small, long lasting streams of liquid water. b. as surface oceans. c. as ice at the poles and water vapor in the atmosphere. d. nowhere at all. The planet is completely dry.
c. as ice at the poles and water vapor in the atmosphere.
For a planet to have substantial amounts of liquid water on its surface, it must have a. temperature between 0°C and 100°C. b. both temperature and atmospheric pressure at the triple point of water. c. atmospheric pressure above the triple point of water. d. atmospheric pressure exactly at the triple point of water. e. temperature above the triple point of water.
c. atmospheric pressure above the triple point of water.
Suppose that a spacecraft is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose the spacecraft flips over backwards and fires its rocket engine to slow its speed to 4.96 miles per second. The spacecraft will then a. coast down to a slightly lower circular orbit. b. escape from the Earth. c. follow an ellipse that descends a bit and then rises again. d. follow an ellipse that rises a bit and then descends again.
c. follow an ellipse that descends a bit and then rises again.
Mercury rotates so that it a. always keeps the same side toward the Sun so that solar time never changes. b. has a solar day that lasts for one complete orbit around the Sun. c. has a solar day that last for two complete orbits around the Sun. d. has a solar day that last for three complete orbits around the Sun.
c. has a solar day that last for two complete orbits around the Sun.
The force of gravity explains a. how planets move but not how objects fall on Earth. b. how objects fall on Earth but not how planets move. c. how the tides work but not how lightning works. d. how objects fall on Earth but not how the tides work. e. how the Sun shines but not how planets move.
c. how the tides work but not how lightning works.
The circular structures on the surface of the Moon are the result of a. volcanos b. moonquakes c. impacts d. gas bubbles e. fortifications
c. impacts
The Moon's orbit around the Earth a. is exactly circular. b. is somewhat elliptical but not enough to affect eclipses. c. is elliptical enough to give us an annular solar eclipse when the Moon is near its apogee. d. is elliptical enough to give us an annular lunar eclipse when the Moon is near its perigee.
c. is elliptical enough to give us an annular solar eclipse when the Moon is near its apogee.
The Law of Inertia states that a moving object will a. always stops b. keep moving if a force pushes it c. keep moving if no force acts on it d. stop if no force acts on it e. never stops
c. keep moving if no force acts on it
When Newton's Laws were applied to predict the exact motion of the planet Uranus, the prediction failed to agree with very precise measurements. This failure led to the discovery a. that Newton's Theory of Gravity is not correct. b. that the Sun wobbles. c. of the Planet Neptune. d. of the Planet Pluto. e. of an invisible moon of Uranus.
c. of the Planet Neptune.
The Earth's magnetic field plays an essential role in a. keeping the Moon in orbit. b. protecting the Earth from ultraviolet light from the Sun. c. protecting the Earth from charged particles from the Sun. d. maintaining the Earth's rotation. e. the manufacture of refrigerator magnets.
c. protecting the Earth from charged particles from the Sun.
Mercury rotates so that its sidereal day lasts for a. one complete orbit around the Sun. b. two complete orbits around the Sun. c. two thirds of a complete orbit around the Sun. d. three complete orbits around the Sun. e. one and a half complete orbits around the Sun.
c. two thirds of a complete orbit around the Sun.
If the planets are numbered from 1 to 8, going outward from the Sun, the planet Mars is number a. 1 b. 2 c. 3 d. 4 e. 5
d. 4
Suppose that you try to lift an object by exerting an upward force of 5 Newtons on it. If gravity exerts a force of 10 Newtons downward on the object, what is the total force on the object? a. 15 Newtons upward. b. 15 Newtons downward. c. 15 Newtons downward. d. 5 Newtons downward. e. 10 Newtons downward.
d. 5 Newtons downward.
What total force will cause an object with a mass of 50kg to gain 1 meter per second every second? a. 1 Newton b. 9.8 Newton c. 5 Newton d. 50 Newton e. 490 Newton
d. 50 Newton
Which of these Mars rovers has been operating on the surface of Mars for six years so far (as of 2018). a. Pathfinder b. Spirit c. Opportunity d. Curiosity e. Surveyor
d. Curiosity
The International Space Station (ISS) is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose that it is desired to raise it to a new circular orbit, farther from the surface by having a rocket give it one or more short boosts. Which of the following schemes will work? a. Increase its speed to 6 miles per second to put it on a rising path. b. Increase its speed to 8 miles per second to put it on a rising path. c. Increase its speed to 6 miles per second to put it on a rising path and give it another speed boost when its distance from the Earth stops increasing. d. Increase its speed to 6 miles per second to put it on a rising path and give it another speed boost when its distance from the Earth stops increasing. e. Decrease its speed to 4.9 miles per second and then give it a speed boost when its distance from the Earth stops decreasing.
d. Increase its speed to 6 miles per second to put it on a rising path and give it another speed boost when its distance from the Earth stops increasing.
The first space probe to place a robotic rover on the surface of Mars was a. Mariner 9. b. Viking 1. c. Surveyor 1. d. Pathfinder. e. Spirit and Opportunity.
d. Pathfinder.
The currently accepted theory of how the Moon formed is the a. capture theory. b. co-formation theory. c. breakup or fission theory. d. collision theory. e. divine intervention theory.
d. collision theory.
The statement that lunar material is much "dryer" than Earth material refers to the absence of a. liquid water b. ice c. mud d. hydrated minerals
d. hydrated minerals