Astronomy Exam 2

Remnants of volcanic activity on the asteroid Vesta indicate that members of the asteroid belt:

occasionally grow large enough to become differentiated and geologically active

Rings of giant planets are very thin compared to their diameters mainly because:

of collisions between ring particles

The mass of all the known asteroids combined would be as much as:

one-third the mass of the Moon

If a moon has a retrograde orbit then it

orbits clockwise as viewed from north pole

Particles that make up the rings of Uranus and Neptune are composed of:

organic material that has darkened due to bombardment by cosmic rays

If plant life were to die on Earth:

oxygen would disappear from the atmosphere

It took approximately __________ years for oxygen to become a large component of the Earth's atmosphere.

1 billion

Compared to the dark-colored regions on the surface of the Moon, the light-colored regions are approximately:

1 billion years older

What would you study in order to determine the timescale on which the Earth's magnetic field reverses direction?

A spreading center on the sea floor

The largest volcanic mountains in the Solar System are found on:

Mars

We have direct evidence for the current existence of water on the surface of which terrestrial object?

Mars

Mars has a diameter that is approximately half that of Earth's. If the interiors of these planets are heated by radioactive decays, how does the heating rate of Mars' interior compare to that of Earth's?

Mars' heating rate is 0.12 times that of Earth's.

Mars, Venus, and Earth are much less heavily cratered than Mercury and the Moon. This is explained by the fact that:

Mars, Venus, and Earth were geologically active longer than Mercury and the Moon

According to studies of impact cratering, which of the terrestrial planets has the oldest surface?

Mercury

Which terrestrial planet shows the least evidence of recent volcanic activity?

Mercury

Which of the following is a remnant from space that has hit the surface of the Earth?

Meteorite

Why do we find methane clouds above water clouds in the atmosphere of Saturn?

Methane is in a liquid/gas state at lower temperatures than water.

Which of the giant planets was predicted to exist mathematically before it was ever seen through a telescope?

Neptune

Roughly how often does a high tide occur?

Once every 12 hours

If a radioactive element has a half-life of 10,000 years, what fraction of it is left in a rock after 40,000 years?

One-sixteenth

Which of the following processes did NOT contribute to Earth's secondary atmosphere?

Oxidation

__________ in our atmosphere is a direct consequence of the emergence of life.

Oxygen

Which of following is FALSE?

Pluto has a mass that is 1/10 times the Earth's mass.

Where do Uranus's and Neptune's high magnetic fields originate?

Salty oceans

If you could find a large enough ocean, which one of these planets would float in it?

Saturn

The fastest zonal winds are found on:

Saturn and Neptune

Compare two blackbody objects, one at 200 K and one at 400 K. How much larger is the flux from the 400 K object, compared to the flux from the 200 K object?

Sixteen times as much

Which of the following is NOT a requirement for a planetary magnetic field?

Solid iron core

An asteroid with an albedo of 0.1 and a comet with an albedo of 0.6 are orbiting at roughly the same distance from the Sun. How do their temperatures compare?

The asteroid is hotter than the comet.

Why did the terrestrial planets lose their primary atmospheres?

Their low gravities couldn't hold them.

Why are all clouds on Jupiter not white, as on Earth?

There are impurities in their ice crystals.

The Jovian atmospheric vortices are created by a combination of the Coriolis effect and:

convection

Which of the following is NOT a factor that helps explain Earth's lack of craters compared to the Moon?

Higher density interior

Band systems on Saturn, Uranus, and Neptune are most prominent when viewed in which wavelength regime?

Infrared

Which object has turned itself inside out numerous times, leading to lighter elements escaping, sulfur compounds composing the crust, and heavier elements making up the core?

Io

Which property of a moon might lead you to believe it was a captured asteroid?

It rotates clockwise around the planet when viewed from the planet's north pole.

Which of the following is the BRIGHTEST part of a comet?

Its coma

Which of the following does NOT contribute to more extreme seasonal variations on Mars compared to Earth?

Its spin axis is tilted more with respect to its orbital plane.

All the giant planets except __________ experience seasons.

Jupiter

In 1994, dozens of fragments of Comet Shoemaker-Levy 9 collided with:

Jupiter

The strongest magnetic fields in the Solar System are found on which planet?

Jupiter

The fact that Jupiter's radius is contracting at a rate of 1 mm/year results in:

Jupiter radiating more heat than it receives from the Sun

A comet having an orbit of 50 years would likely have come from the:

Kuiper Belt

Which of the following does NOT contribute to the large size of Mars's volcanoes?

Lack of atmosphere

If you obtained a sample of rock from Venus and determined the abundances of 238U and 207Pb in it, and found that for every 1 uranium atom there were 3 lead atoms, then what would the age of this rock be? Note that 238U decays to 207Pb with a half-life of 700 million years. Assume that there was no 207Pb in the rock when it originally formed.

1.4 billion years

If the flux of sunlight on a planet suggested its temperature should be 200 K, but its actual temperature was 220 K, then how much more energy does this planet emit relative to the energy it receives from its parent star?

1.5 times more energy

If the Himalaya mountain range is presently 8,000 m in height and is rising at a rate of 0.5 m per century because of the convergence of two continental plates, how long did it take to create this mountain range?

1.6 million years

The nucleus of the typical comet is approximately __________ in size.

10 km

What is the surface temperature of a star that has a peak wavelength of 290 nm?

10,000 K

At what wavelength does your body radiate the most given that your temperature is approximately that of the Earth, which is 300 K?

10-5 m

Earth has roughly __________ times more atmospheric pressure than Mars and __________ times less than Venus.

100; 100

You could fit roughly __________ Jupiters across the diameter of the Sun and roughly __________ Earths across Jupiter's diameter.

10; 10

The North American Plate and the Pacific Plate are sliding past one another at a rate of approximately 3 cm/year. San Francisco, which is located on the edge of the North American Plate, is sliding southward toward Los Angles, which is located on the Pacific Plate. If they are currently separated by a distance of 600 km, how many years will it take for the two cities to meet?

20 million years

The greenhouse effect raises Earth's surface temperature by roughly:

35 K

The inner core of each of the giant planets is made up of rocky material that is __________ times the mass of the Earth.

5 to 10

You observe Neptune as it occults a background star when the relative velocity between Neptune and the Earth is 30 km/s, and the star crosses through the middle of the planet and disappears for 27.6 minutes. What is Neptune's diameter?

5 × 104 km

If Saturn has a semimajor axis of 10 AU and an albedo of 0.7, what is its expected temperature?

65 K

What must an asteroid have in order for us to determine its mass?

A moon

Humans cannot survive on the surface of Mars for long periods of time because:

All of the above are valid reasons

Which of the giant planets does NOT have rings?

All of the giant planets have rings.

Given the thickness and composition of Venus's atmosphere, by how much would you expect its average surface temperature to change between day and night?

Almost no change at all

Which object would have the largest impact if it were to strike the Earth?

An asteroid moving at 200 m/s

The darkest asteroids are:

C-type

Which of the following is NOT geologically active?

Callisto

Which group of meteorites represents the conditions in the earliest stages of the formation of the Solar System?

Chondrites

Which group of meteoroids is more likely to have compositions indicative of those in the early Solar System?

Cometary meteoroids

What is the most common geologic feature seen on moons?

Craters

What is the best explanation for the heating of Earth's interior today?

Decay of radioactive elements

Why does the dust tail separate from the ion tail?

Dust is more massive than ions, so it accelerates less.

Based on the assumption that a liquid, conducting core and rapid rotation are both required for a magnetic field to operate, which terrestrial planets would you expect to have magnetic fields?

Earth and Mars only

Which of the following will NOT be a consequence of Earth's consumption of the bulk of its radioactive "fuel" in the future?

Earth will spin more slowly on its axis.

Based on the number of impact craters observed per square meter on their surface, place these terrestrial planets in order of youngest to oldest surface:

Earth, Venus, Mercury

Which moon gives rise to the particles that make up Saturn's E ring?

Enceladus

Which of the following moons is thought to have a vast ocean of water beneath its thin frozen surface?

Europa

Which of the following does NOT describe comets in the Oort Cloud?

Flattened distribution

What would you observe in order to accurately measure the rotational period of a giant planet?

Synchrotron emission

Suppose we discover a comet whose orbit was very highly eccentric, retrograde, had a very large tilt with respect to the ecliptic plane, and a period of 2,000 years. Where is the most likely place of origin for this comet?

The Oort Cloud

The colors of the cloud bands on Jupiter and Saturn are due primarily to differences in their:

chemical compositions

Which of the following contributes most to the large difference in the average daytime and nighttime temperatures on the Moon?

The lack of an atmosphere

Which of the following factors does NOT directly influence the temperature of a planet?

The size of the planet

Continental drift occurs at a typical rate of a few:

cm/year

Which of the following is the hottest part of the atmosphere?

Thermosphere

Why would a planet's rings reflect 50 percent of the sunlight they receive?

They are made of ice.

Why are Jupiter and Saturn not perfectly spherical?

They rotate rapidly.

Which of the following moons do scientists believe most closely represents the primordial Earth, although at a much lower temperature?

Titan

If water vapor was released from Venus's surface due to tectonic activity into its upper atmosphere, what would most likely happen to it?

UV light would break apart the water molecules, and the hydrogen would be lost into space.

All the giant planets radiate more energy into space than they receive from the Sun EXCEPT:

Uranus

__________ has the most extreme seasons of any planet in the Solar System.

Uranus

Based solely on mass, which of the following terrestrial planets would you expect to retain a secondary atmosphere?

Venus

Which of the following has an atmosphere of primarily carbon dioxide?

Venus

What is unique about Venus's rotation?

Venus rotates in the opposite direction compared to the direction it orbits the Sun.

Venus's surface temperature is fairly uniform from the equator to the poles because:

Venus rotates slowly so Coriolis forces do not disrupt Hadley circulation

Which molecule moves with the fastest average speed in the Earth's atmosphere in thermal equilibrium?

Water (atomic mass = 18)

How do particles from Enceladus wind up in Saturn's E ring?

Water geysers erupt from the surface and expel them into space.

Most asteroids are closest in shape to:

a potato

If you wanted to search for faint rings around a giant planet by sending a spacecraft on a flyby, it would be best to do so:

after the spacecraft passed the planet

The nitrogen in the Earth's atmosphere came from:

ammonia delivered by comet impacts

Meteorites contain clues to all of the following EXCEPT:

changes in the rate of cratering in the early Solar System

meteorites have clues containing all the following except

changes in the rate of cratering in the solar system

Jupiter emits a large amount of radio emission because:

charged particles blasted off of Io's surface move through Jupiter's magnetic field

plate tectonics is not responsible for

canyons

The main greenhouse gases in the atmosphere of the terrestrial planets are:

carbon dioxide and water vapor

differentiation

density

Eris and Ceres are examples of:

dwarf planets

We refer to some of the inner regions of Jupiter and Saturn as metallic hydrogen because they:

efficiently conduct electricity

Most comets originate:

far from the planets, many thousands of AU from the Sun

The current theory is that a planet will have a strong magnetic field if it has:

fast rotation and a liquid core

As a group, the giant planets all rotate __________ terrestrial planets.

faster than

When a comet comes close to the Sun, its volatile ice sublimates and transforms directly from the solid to __________ phase.

gas

Uranus and Neptune do not have bands as distinct as those on Jupiter and Saturn, because Uranus and Neptune:

have wind speeds that vary more smoothly from the equator to the poles

The one orbital characteristic both short- and long-period comets share is:

highly eccentric orbits

The gas giants are composed primarily of:

hydrogen

The Earth releases the energy it receives from the Sun by emitting __________ radiation.

infrared

The fact that Earth's interior is differentiated suggests that:

it was liquid at some point in the past

Jupiter's rings are made of material from:

its largest, innermost moons

The lithosphere of a planet is:

its solid surface

In the past, the Moon was closer to the Earth and the difference in the heights of the ocean at high and low tides were:

larger

Flows of material surrounding Martian craters suggest:

the presence of water in surface rocks

The major difference in the composition of Earth's atmosphere compared to the atmospheres of Venus and Mars is a direct consequence of:

life on the planet

Uranus and Neptune are bluish green because they contain large amounts of:

methane

The surface of the dwarf planet Eris has very high albedo and is covered with:

methane ice

The rovers named Spirit and Opportunity that recently explored Mars's surface discovered:

minerals that must have formed in an environment rich in liquid water

Of the giant planets, only Jupiter and Saturn have thick inner layers of:

molecular and metallic hydrogen

As a blackbody becomes hotter, it also becomes __________ and __________.

more luminous; bluer

Antarctica is the best hunting ground for meteorites for all of the following reasons EXCEPT:

more meteorites fall there than on other locations on Earth

Ring material:

must constantly be renewed

Neptune and Uranus probably took longer to form than Jupiter and Saturn, because the solar nebula was __________ at the radius of Neptune and Uranus.

not as dense

Earth's innermost core is solid, not liquid, because:

the pressure is too high for a liquid state

Suppose an earthquake occurs on an imaginary planet. Scientists on the other side of the planet detect primary waves but not secondary waves after the quake occurs. This suggests that:

part of the planet's interior is liquid

Cometary nuclei are most likely:

porous

The age of the Solar System can be determined most accurately by:

radioactive dating of rocks retrieved from the Moon

Based on the age of the light- and dark-colored regions of the Moon and the number of craters observed in these regions, we know that impacts in the inner Solar System:

rapidly decreased approximately 3 billion years ago

Most asteroids are:

small

Neap tide occurs when the Moon is in the first or third quarter phase and results in:

smaller than usual tides

Erosion on the surface of the Moon is primarily caused by:

solar radiation

erosion on the surface of the moon is caused by

solar radiation

The most common type of meteorites are:

stony meteorites

Runaway convection in the Earth's atmosphere can lead to:

storms

The varied colors found on Io's surface are due to the presence of various molecules containing:

sulfur

The smallest craters are found on:

the Moon

Heating from __________ causes the top of the Earth's stratosphere to be warmer than the bottom.

the ozone layer absorbing UV light

Studies of the amount of cratering at different locations on the Moon indicate that:

the rate of cratering in the Solar System has changed dramatically over time

The shape of the Earth's magnetosphere is modified by:

the solar wind

The two layers of Earth's atmosphere that have temperature gradients that allow convection to occur are:

the troposphere and the mesosphere

A planet will have bands in its atmosphere like Jupiter and Saturn if:

the wind speeds vary greatly with latitude

Despite the high temperatures deep in the interior of giant planets, their cores remain liquid because:

they are under very high pressures

Each season is 42 years long on Uranus because:

they change on the timescale of Uranus' orbital period

Comet nuclei, absent their tails, are very dark because:

they have organic molecules mixed with ice

All weather and wind on Earth are a result of convection in the:

troposphere

Without the ozone layer, life on Earth would be in danger from increased levels of __________ radiation.

ultraviolet

The presence of greenhouse gases like carbon dioxide and water vapor in a planet's atmosphere is direct evidence of:

volcanic activity

The compositions of Uranus and Neptune differ primarily from that of Jupiter and Saturn in that the outer two planets contain more:

water ice

The minimum size of a meteoroid that is capable of surviving its passage through the Earth's atmosphere and hitting the ground is about as big as:

your fist