Astronomy Exam 2
Compared to the Earth, the planet Jupiter is roughly
10 times as large
What total force will cause an object with a mass of 10kg to gain 5 meters per second every second?
50 Newtons
The first spacecraft to go into orbit around Saturn was
Cassini-Huygens.
Which of these planets is the farthest from the Sun?
Mars
The first space probes to land on another planet were from the
Russian Venera series.
Pluto rotates on its axis
about once a week
Mars has
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
as ice at the poles and water vapor in the atmosphere.
Galileo's approach to understanding moving objects was to
build things that he could measure.
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?
comet
Relative to the distant stars, Mercury
completes 1.5 rotations each time it orbits the Sun.
Mars' orbit is currently (within the last few hundred years)
elliptical enough to make the intensity of sunlight vary by 40 percent.
The magnetic field of Earth's Moon is
essentially zero
The magnetic field of Mars is
essentially zero
Many asteroids can best be described as
flying rocks or possibly flying mountains.
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 a rocket pushes it and quickly increases its speed to 6 miles per second. The ISS will then
follow an ellipse that rises and then descends again.
According to our current model of how planets form magnetic fields, the magnetic field of Saturn is much less than the magnetic field of Jupiter because Saturn
has less metallic hydrogen in its core than Jupiter.
The Oort Cloud is thought to have originated when
icy objects were ejected outward from among the Jovian planets.
The circular structures on the surface of the Moon are the result of
impacts
The presence of frozen water on Venus is
impossible because every part of it is too hot for water ice.
If the acceleration of an object is zero, its speed
is not changing.
The Surveyor series of spacecraft
made unmanned landings on the Moon in the 1960s.
When a bullet is fired from a gun, the bullet keeps moving after it leaves the gun barrel because
no force stops it.
The observed magnetic field of Mercury is surprising because it was expected to have
no magnetic field at all because it rotates so slowly.
The distance from the Earth to the Sun is
one astronomical unit.
Which of these is a distinctive feature of the Earth's atmosphere?
temperature and pressure permit all three forms of water.
Asteroids are
usually found in the asteroid belt, between the orbits of Mars and Jupiter.
The distance from the Earth to the Moon
varies enough that sometimes we get an annular solar eclipse.
At present (within the last few hundred years) the orbit of Mars around the Sun is
very elliptical so that.the intensity of sunlight varies by 40 percent.
The Law of Inertia says that if an object is not acted on by any outside force, its acceleration
will always be zero.
The number of moons of Mercury is
0
Uranus rotates on its axis once in about
17 hours
The density of water is 1000kg/m³ while the density of iron is 7800kg/m³. Which of the following values is a plausible value for the density of a terrestrial planet?
5000kg/m³
Once its rockets have ceased firing, an Intercontinental Ballistic Missile will follow a path that is best described as
an ellipse with the center of the Earth at one focus.
Pluto has
an extensive atmosphere of nitrogen and methane.
Saturn has
an extensive ring system made of ice-covered rocks.
Kepler's Laws
are explained by a force that attracts each planet to the Sun.
The Oort cloud of our Sun reaches
at least a quarter of the way to the nearest star.
For a planet to have substantial amounts of liquid water on its surface, it must have
atmospheric pressure above the triple point of water.
Asteroids are usually found in the asteroid belt, which is
between the orbits of Mars and Jupiter.
Milankovich cycles refer to
changes in the intensity of sunlight due to shifts in both the Earth's orbit and rotation axis.
Freely falling objects with different masses fall with the same acceleration because
gravity exerts more force on the more massive object.
The density of rock is about 3000kg/m³. The density of the Earth is
greater than 3000kg/m³ because the Earth has an iron core.
The statement that lunar material is much "dryer" than Earth material refers to the absence of
hydrated minerals.
Comets are usually made of
ice and possibly frozen gas
Kuiper Belt objects are usually made of
ice and possibly frozen gas
The photosphere of a protostar
is where light is last scattered
The Jovian planets typically have
large systems of moons.
The number of maria on the side of the Moon facing away from the Earth is
less than on the side facing Earth.
Compared to the rest of the Lunar surface, the Lunar Maria are
lower and younger
The temperature on Jupiter is
much colder than anywhere on Earth
The temperature on Saturn is
much colder than anywhere on Earth.
The Moon rotates on its axis relative to the distant stars
once every sidreal month
The Opportunity Mars rover
operated on Mars for fifteen years.
The magnetic field of Saturn is
similar in intensity to the Earth's magnetic field.
In Kepler's Laws of planetary motion the Earth moves around a Sun that is fixed in space. In Newton's theory,
the Sun and Earth move around a common center of mass.
In Newton's Theory of planetary motion,
the Sun and Earth move around each other.
An astronomical unit is defined to be
the average distance from the Earth to the Sun.
The force that acts on a rocket because its engine is firing is exerted by
the exhaust from the rocket.
According to Aristotle, a thrown spear keeps moving after it has left the spear thrower's hand because
the force of the air disturbed by the spear keeps it in motion.
If you are told that a 20 kilogram object is raised by 10 meters, you know that
the mass of the object is 20 kilograms.
Upon close examination by space probes, the rings of Saturn are found to consist of
thousands of circular rings
The Moon rotates on its axis so that it always keeps the same side
toward the Earth
Which of the following planets or moons has an atmosphere with about 90 times the surface pressure of Earth's.
Venus
Which of the following three systems is regarded as the most normal for a terrestrial planet?
Venus, with no moons at all.
Which of the following spacecraft was the second to fly past Saturn and the first to target the moon Titan?
Voyager 1
Which of the following spacecraft is the only one to have flown past Neptune?
Voyager 2
Which of the following spacecraft is the only one to have flown past Uranus?
Voyager 2
The Great Red Spot is
a hurricane on Jupiter
According to the currently accepted model of how planets generate magnetic fields, a rotating planet with a substantial magnetic field must contain
a liquid electrical conductor.
The magnetic field of Jupiter indicates that its core must contain large amounts of
a liquid that can conduct electricity.
When the Earth passes through the orbit of a broken-up comet, we see
a meteor shower
After a comet's closest approach to the Sun, its tail points
ahead of its direction of motion.
Relative to the distant stars, Venus
completes less than one full rotation each time it orbits the Sun.
A meteoroid is a medium-sized rock that is
drifting in space
The rotation axis of Saturn is
inclined at an angle to the perpendicular that is similar to Earth's rotation axis.
A unit of mass is the
kilogram
The number of protostars that can be seen right now is
large because they are much brighter than ordinary stars.
The Law of Inertia states that a moving object will
keep moving if no force acts on it.
Which of the following temperatures is closest to what you might expect on the planet Jupiter?
-250F
The number of objects that have been observed to be orbiting in the Outer Oort Cloud is approximately
0
An ion rocket engine produces 1 Newton of thrust. What acceleration can it give to a space probe with a mass of 1000kg?
0.001 m/s².
The angle between the rotation axis of a planet and the perpendicular to the plane of its orbit is called its "axial tilt." The axial tilt of Mercury is
0.01 degrees
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 10kg (including the sail) and sunlight exerts a total force of 2N on the sail. What will be the acceleration of the spacecraft?
0.2m/s².
What total force will cause an object with a mass of 10kg to gain 0.1 meters per second every second?
1 Newton.
Saturn rotates on its axis once in about
10 hours
The number of objects that have been observed to be orbiting in the Kuiper Belt is approximately
1000
The Earth's distance from the Sun is defined to be 1 astronomical unit. Neptune is about 30 astronomical units from the Sun. An object in the Inner Oort Cloud might be at a distance from the Sun of
15000 astronomical units
The first human landing on the Moon was Apollo 11 in
1969
The number of moons of Mars is
2
Suppose that you lift an object by exerting an upward force of 12 Newtons on it. If gravity exerts a force of 10 Newtons downward on the object, what is the total force on the object?
2 Newtons
The inclination angle of a planet's rotation axis is defined so that a planet that is rotating in the usual direction about an axis that is perpendicular to the plane of the solar system would have an inclination of 0°, while a planet that is rotating in the opposite (retrograde) direction about an axis that is perpendicular to the plane of the solar system would have an inclination angle of 180°. The inclination angle of the planet Neptune is closest to
30°.
Compared to the Earth, the planet Uranus is roughly
4 times as large
Suppose that you lift an object by exerting an upward force of 15 Newtons on it. If gravity exerts a force of 10 Newtons downward on the object, what is the total force on the object?
5 Newtons.
The density of water is 1000kg/m³ while the density of rock is 3000kg/m³. Which of the following values is a plausible value for the density of a Jovian planet?
700kg/m³
The first human landing on the Moon was
Apollo 11 in 1969
Facts
Average Distance from Earth to Sun = 1 astronomical unit = 1 au. Diameter of Sun = 1/100 au Diameter of Earth = 1/10,000 au Earth-Moon Distance = 1/400 au
The largest four moons of Jupiter are referred to as the
Galilean satellites
The first spacecraft to go into orbit around Jupiter was
Galileo
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?
Galileo really did the experiment.
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 and one object is twice as heavy. Who predicted that both objects would hit the ground at the same time?
Galileo.
Who discovered Newton's First Law of Motion?
Galileo.
Which of the following objects is the largest moon of Jupiter?
Ganymede
Gerard Kuiper predicted that the region we now call the "Kuiper Belt" should be empty.
He was incorrect because he assumed a mass for Pluto that is now known to be too large.
The Apollo program was thought to be part of a "race to the Moon" with the Soviet Union. Actually
It was a close race. The Soviets actually built a Moon rocket and tested it.
The most likely candidate for a second star in our Solar system was
Jupiter
Which of these sequences places the outer planets in the correct order from the Sun, from the closest to the farthest.
Jupiter, Saturn, Uranus, Neptune (farthest)
The angle between the rotation axis of a planet and the perpendicular to the plane of its orbit is called its "axial tilt." Which of these planets has an axial tilt that is less than one degree?
Mercury
Which of these sequences places the inner planets in the correct order from the Sun, from the closest to the farthest?
Mercury, Venus, Earth, Mars (farthest)
The first space probe to test the air-bag landing system was
Pathfinder.
Which of the following spacecraft were the first to fly past Jupiter?
Pioneer 10 and Pioneer 11
A rocket 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 lower it to a new circular orbit, slightly closer to the surface. The rocket flips over and fires its main rocket engine in a short burst to slow its speed to 4.96 miles per second. What must it do next?
Slow its speed again by a bit when its distance from the Earth stops decreasing.
Why couldn't we just fly a Space Shuttle to the Moon for at least a fly-by?
The Space Shuttle did not have enough fuel to reach escape velocity.
Why don't we just shoot all of our really nasty waste products into the Sun where they could not possibly bother anyone?
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?
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?
The force that the floor of the elevator exerts on you and the force that you exert on the floor of the elevator.
Which of the following objects is the largest moon of Saturn?
Titan
A lunar crater is best described as
a circular ring wall surrounding a flat area.
Jupiter has
a few rings made of dark rocks.
The magnetic field of Mercury is
about 1% of the Earth's magnetic field.
The largest moon of Pluto has
about 1/2 the diameter of Pluto.
The magnetic field of Jupiter is
about 10 times the intensity of the Earth's magnetic field.
The plane that contains the Earth's orbit around the Sun is also called the plane of the ecliptic. When you look for the planets in the sky, you expect to find
all of them near the ecliptic
Saturn's magnetic North and South poles are
almost exactly aligned with its rotation axis.
The rotation axis of Uranus is
almost in the plane of its orbit so that its ring system can sometimes be seen as near-circles.
In comparison to Kepler's Laws of Planetary Motion, Newton's theory of Universal Gravitation predicted
almost the same motions but with corrections.
Jupiter has
an atmosphere of Hydrogen and Helium with no real surface.
Saturn has
an atmosphere of Hydrogen and Helium with no real surface.
Neptune has
an atmosphere of Hydrogen and Helium with some methane.
Uranus has
an atmosphere of Hydrogen and Helium with some methane.
Titan has
an atmosphere whose temperature and pressure permit liquid methane.
Current theory says that the Moon formed when
another planet collided with the Earth.
Space probes often use gravitational slingshot maneuvers. The main purpose of these maneuvers is to
change the direction and speed of the probe without using rockets.
The orbit of Pluto
crosses the orbit of Neptune
Most Kuiper Belt objects can best be described as
dirty snowballs or possibly flying icebergs.
Neptune's magnetic North and South poles are
displaced from its rotation axis poles and also from the center of the planet.
Uranus's magnetic North and South poles are
displaced from its rotation axis poles and also from the center of the planet.
According to current theories it seems likely that "rogue planets" or planetary mass objects that are not in orbit around any particular star
exist and may be more common than planets in orbit around stars.
What we refer to as a `Saturn Ring-plane Crossing' corresponds to what season on Saturn?
fall or spring equinox.
A rocket that leaves the Earth's atmosphere at a speed of 4 miles per second will
follow an elliptical path that is partly below the surface of the Earth.
When a large interstellar cloud collapses, it usually
fragments into several smaller clouds which then form stars
Mars
has a solar day that is very close to an Earth day in length.
Mercury rotates so that it
has a solar day that last for two complete orbits around the Sun.
The Kuiper Belt
has been confirmed now that hundreds of objects in the belt have been observed.
The Curiosity Mars rover
has been operating on Mars for eight years so far (as of 2020).
The force of gravity explains
how the tides work but not how lightning works.
According to Newton's Law of Gravity, the gravitational attraction of the Earth for other objects, such as the Moon, apples on trees and spacecraft in low earth orbit,
is smaller for objects farther from the Earth but never vanishes entirely.
The Oort Cloud
is the hypothetical (but mostly unobserved) starting point of long-period comet
According to the current definition of a planet, Pluto is not regarded as a planet because
it has not cleared its neighborhood of other orbiting objects.
In the original Solar Nebula, objects that condensed far from the protoSun tended to include large amounts of frozen gas and water ice because, in that part of the nebula
it was cold enough for gases and water to condense.
Galileo said that a moving object with nothing pushing or pulling on it will always
keep moving at the same speed.
The dark markings on the Full Moon that make up the face of the "Man in the Moon" are called Lunar
maria
Which of the following space probes flew past Saturn but not past Jupiter?
none of these
The key argument against the Moon forming from the Earth alone, by breakup of a single object is that the Moon's
orbit is tilted relative to Earth's equator.
The radiant of a meteor shower is the
point in the sky the meteors seem to be coming from.
The presence of frozen water on Mercury is
possible because it has almost no axial tilt so that its poles never directly face the Sun.
The Earth's magnetic field plays an essential role in
protecting the Earth from charged particles from the Sun.
Space probes often visit several planets before getting to their final destinations. The main reason they do this is to
reduce the amount of rocket fuel needed.
Asteroids can be made of
rock and possibly iron.
Venus
rotates backwards so that the Sun rises in the West.
Since the last Apollo mission to the Moon and the last Soviet LUNA sample-return mission
spacecraft began to be sent there again by 1994.
An artificial satellite such as the International Space Station stays up because
the Earth curves out from under it as fast as it falls.
Our Sun sends out intense streams of charged particle radiation. The radiation is prevented from hitting the Earth's atmosphere by
the Earth's magnetic field.
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
the heavier object would hit the ground long before the lighter one.
One way to change the course of an asteroid is to place a `mass driver' on it. The mass driver is really just a catapult that throws things (like rocks for example) away from the asteroid. The force that acts on the combined object (mass driver plus asteroid) is actually exerted by
the rocks that the catapult throws.
Suppose that an object with a mass of one kilogram and an object with a mass of two kilograms are both in free fall near the Earth's surface. As compared to the one kilogram object, the two kilogram object accelerates
the same because gravity pulls on it more strongly and it has more inertia.
Moon missions since 2007 have mostly been focused on
the search for water needed for a Moon base.
In the ancient Greek theory of gravity, everything was attracted to the center of the universe. In Newton's theory of gravity, everything was attracted
to every other object in the universe.
When Newton calculated the magnitude and direction of the acceleration of Earth's Moon, he found that the direction was
toward the Earth.
When Newton calculated the magnitude and direction of the acceleration for a planet that was following Kepler's Laws, he found that the direction of the acceleration was
toward the Sun.
