Astronomy Chapter 8-13 Review Questions

In which atmospheric layer are almost all water based clouds formed?

Troposphere

Compare the current atmospheres of Earth, Venus, and Mars in terms of composition, thickness (and pressure at the surface), and the greenhouse effect.

Earth's atmosphere is about 4/5 nitrogen and 1/5 oxygen; Venus' atmosphere is mostly carbon dioxide, with a pressure about 90 times higher than Earth; Mars' atmosphere is also mostly carbon dioxide, with a pressure only about one hundredth that of Earth. Venus has had an ongoing runaway greenhouse effect, leading to extraordinarily high surface temperatures.

Explain how high-speed impacts form circular craters. How can this explanation account for the various characteristic features of impact craters?

Escape velocity (the minimum speed a projectile approaching Earth or the moon will hit with). The explosion from the impact displaces material in a symmetrical circle. This accounts for the bowl shape, because at initial impact the first part of the projectile to hit the surface will go farther down.

Explain the runaway refrigerator effect and the role it may have played in the evolution of Mars.

Gravity is not strong enough to hold a gaseous atmosphere, so the atmosphere would have gotten thinner as gas escaped. This would lead to lower temperatures, and more gas would have frozen and deposited out of the atmosphere, lowering temperatures still further. The thinner atmosphere and colder temperatures would lead to the loss of most water from the planet, except for water ice, and underground saltwater.

Give brief descriptions of both the Kuiper belt and the Oort cloud.

Kuiper Belt extends right outside of the orbit of Neptune. It is similar to the asteroid belt, but it is much larger. Most asteroids that come out of it are made up of ice. The Oort Cloud is the most distant region of our solar system. Even the nearest objects in the Oort Cloud are thought to be many times farther from the Sun than the outer reaches of the Kuiper Belt.

How do impacts by comets and asteroids influence Earth's geology, its atmosphere, and the evolution of life?

Large enough comets can cause extinction in certain species, changing then how new species will evolve.

Briefly describe the greenhouse effect

Light penetrates our atmosphere and the heat is absorbed by the ground, the heat at Earth's surface is reemitted as infrared or heat radiation. However the molecules in our atmosphere that lets visible light through absorbs the infrared waves, trapping the heat in our atmosphere.

At the pressures in Jupiter's interior, describe the physical state of the hydrogen found there.

Liquid-metallic form not seen on Earth.

What is the thickest interior layer of Earth? Thinnest?

Mantle is thickest, crust is thinnest

What are the maria composed of? Is this material found elsewhere in the solar system?

Maria are composed of dark-colored basalt.

What is the primary source of Jupiter's internal heat?

Most of the internal energy of Jupiter is primordial heat, left over from the formation of the planet 4.5 billon years ago, when it gathered together from smaller "planetesimals" and accreted gas.

What are the seasons like on Jupiter?

Since Jupiter's spin axis is only tilted about 3° from the perpendicular, it does not experience seasons at all.

How might Venus' atmosphere have evolved to its present state through a runaway greenhouse effect?

Sun evaporated water on Venus, releasing carbon dioxide. The carbon dioxide prevented infrared radiation from escaping the planet, leading to a rise in temperatures and of water and release of carbon dioxide. Sunlight would break up water vapor molecules higher in the atmosphere into hydrogen, which escaped the planet, and oxygen, which combined with surface rocks. The loss of water reduces the planet's ability to absorb carbon dioxide.

Although he did not present a mechanism, what were the key points of Alfred Wegner's proposal for the concept of continental drift?

That South America and Africa were joined together in one land mass called Pangea, they were though separated. There were similar fossils found on both continents suggesting that they were together, along with their matching borders.

Briefly describe NASA's Spaceguard Survey. How many objects have been found in this survey?

The Spaceguard Survey is designed to discover all near-Earth asteroids (NEAs) that are greater than 1 km in diameter. Close to 1000 objects of this size have been found.

Explain the evidence for a period of heavy bombardment on the Moon about 4 billion years ago.

The age of the moon was calculated by the size and number of craters, assuming there has been a constant crater impact rate. However this would date the moon to being created before the moon, so it was calculated that the impact rate was much higher four billion years ago.

What are the difficulties with the capture hypothesis of the Moon's origin?

The moon is made of similar materials of those to Earth's mantle, so it seems unlikely that Earth would've captured an object with the same inner composition

Outline the main events in the Moon's geological history.

The moon was formed around the same time as the Earth (4.5 to 4.6 billion years ago). The moon has been affected by impacts for billions of years.

What are the moons of the outer planets made of, and how is their composition different from that of our Moon?

The moons of the outer planets consist of a mixture of ice and rock, whereas our Moon is just rock.

What is the source of Earth's magnetic field?

The movement of Earth's liquid metallic core

Explain why visual observation of the gas giants is not sufficient to determine their rotation periods, and what evidence was used to deduce the correct periods.

What is seen visually on each of these worlds is the upper atmosphere, with winds and storms that do not necessarily move at the same rate as the planet as a whole. Radio observations revealed the existence of magnetic fields originating in the cores of these planets. The rotation periods are determined from the fact that the magnetic fields rotate at the same velocity as the interiors.

Describe in three ways in which the presence of life has affected the composition of Earth's atmosphere

1. The sophistication of life caused for an increase in plant population, increasing the amount of oxygen being produced- this accumulation of oxygen was the reason for the creation of the ozone layer 2. The ozone layer filters out UV rays that was only able to be done by living in the depths of water, so when the ozone layer was created animals were able to adapt and live on land, breathing oxygen 3. Living things have removed most of the carbon dioxide from the atmosphere

The features of Mercury are named in honor of famous people in which fields of endeavor?

Artists, writers, composers, and other contributors to the arts and humanities.

How did our exploration of the Moon differ from that of Mercury (and the other planets)?

Because of its proximity to Earth, we have been able to send manned missions to the Moon and return lunar material to Earth for study. Robotic missions have also been used to explore the lunar surface. All other solar system objects—planets, asteroids, and comets—have been studied only by telescope and/or robotic missions. No humans have visited them.

Compare the geology of Callisto, Ganymede, and Titan.

Callisto is an ice-covered moon whose inner materials have never fully differentiated into different-density layers. It has no inner or outer activity and is basically geologically dead. Ganymede has a central rocky core and shows signs of tectonic activity, including regions of young surface terrain and long cracks in the crust. Titan has similar mass, size, and composition to Callisto and Ganymede, but has an active geology of liquid hydrocarbons on the surface, evaporation into the atmosphere, and rain back onto the surface.

Detail some of the anthropogenic changes to Earth's climate and their potential impact on life.

Climate is the change in the atmosphere over time, which has been gradually warming. This could harmful for the health of all living things on the planet.

What is the composition of clouds on Mars?

Clouds on Mars are of three types: dust clouds; water-ice, like those on Earth; and clouds of frozen carbon dioxide crystals (dry ice).

Describe the origin and eventual fate of the comets we see from Earth.

Comets that "fall" into the inner solar system were once located either in the Oort cloud, from the Sun or the Kuiper belt. The Oort cloud is far enough away that the gravitational influence of passing stars can perturb a comet's orbit. Some perturbations can send a comet out into interstellar space never to return. Some of them are likely to crash into planets or the sun.

Describe the two types of comet tails and how each are formed.

Comets typically have both a dust tail and an ion tail. The dust tail is larger and brighter than the ion tail and is formed by the action of sunlight imparting energy to the dust particles and pushing them away gently from the nucleus. The ion tail is composed of charged particles and are pushed away by the streams of charged particles emanating from the Sun (the solar wind). The dust tail tends to curve as the particles go into orbit around the Sun, whereas the ion tail tends to be straighter as the charged particles are pushed in the direction that is away from the Sun.

How are Triton and Pluto similar?

Both Triton and Pluto are very cold worlds in the outer reaches of the solar system. They are similar in size and similar in density, and thus similar in the proportion of rock and ice that makes them up. Both have a thin atmosphere of nitrogen, which freezes and sublimates depending on the temperature.

Describe the nucleus of a typical comet and compare it with an asteroid of similar size.

Comet nuclei are small and are composed of ices, volatile organic compounds, silicate grains, and dust. Asteroids of similar size are denser and contain more stony and/or metallic materials.

Describe the seasons on the planet Uranus.

Each pole experiences a 21-year sunlit "summer" and later a 21-year dark "winter." For the other half of the "Uranus year," the equator receives the light of the Sun and each hemisphere experiences what we would call a normal "day." In all, each pole experiences 42 years of light and 42 years of dark.

What do our current ideas about the origins of the Moon and Mercury have in common? How do they differ?

Early in it's evolution it lost part of its' silicate mantle. While there are many theories for the moon's origin.

Who first calculated the orbits of comets based on historical records dating back to antiquity?

Edmund Halley presented the calculations for 24 cometary orbits in 1705.

What are the main atmospheric heat sources of each of the giant planets?

For Jupiter, Saturn, and Neptune, both sunlight and internal sources provide energy to the atmosphere. Uranus has no or very little internal heat, so it gets its energy from the Sun.

Compare the atmospheric circulation (weather) of the four giant planets.

For both Jupiter and Saturn, convection from their internal heat sources mixes the atmosphere and promotes cloud formation. Their rapid rotation spreads out these cloud features into parallel bands that circle the planets at all latitudes. For Uranus, the circulation is also equatorial and the wind speeds are high. Since there is no convection to mix the gases and create many clouds, Uranus' atmosphere is smeared out and rather featureless. Neptune's wind speeds are much higher than its rotational speed, so the atmosphere smears out into parallel bands like Jupiter and Saturn.

Explain the energy source that powers the volcanoes of Io.

Io is close enough to Jupiter to experience significant tidal heating. This generates enough heat to produce molten silicate lava that erupts as volcanoes.

List, in order of decreasing altitude, the principle layers of Earth's altitude

Ionosphere, Mesosphere, Ozone layer, Stratosphere, Troposphere

The Hubble Space Telescope images of Pluto in 2002 showed a bright spot and some darker areas around it. Now that we have the close-up New Horizons images, what did the large bright region on Pluto turn out to be?

It appears to be a bowl or sea of frozen and perhaps liquid nitrogen, much brighter and younger (no craters visible) than the darker highlands of Pluto.

What is the main consequence of Mercury's orbit being so highly eccentric?

It can be difficult to pick out in the sky and it varies greatly the distance from the sun.

Frozen water exists on the lunar surface primarily in which location? Why?

Near the lunar poles. There are permanently shadowed craters where the ice sits because it has much cooler temperatures in the shade.

Which of the gas giants has the largest icy/rocky core compared to its overall size?

Neptune

What is, by far, the most abundant component of Earth's atmosphere?

Nitrogen (78%)

How was the Mars Odyssey spacecraft able to detect water on Mars without landing on it?

Odyssey used a gamma-ray spectrometer to detect hydrogen below the martian surface.

Why is the shape of the magnetosphere not spherical like Earth?

Our magnetosphere extends farther away from the sun because solar wind is blowing charged particles toward Earth, basically blowing the magnetosphere in that direction because more charged particles are flowing that way.

What evidence do we have for the existence of the Kuiper belt? What kind of objects are found there?

Over a thousand members of the Kuiper belt have been found directly in recent years.we found dwarf planets Pluto, Eris, and Makemake. The size and numbers of these icy objects suggest that many additional smaller bodies must also exist in the same region, in a disk extending out to about 50 AU from the sun.

Describe the main differences between C-type and S-type asteroids.

S-types are stony or silicate-based bodies with few carbon compounds and are more reflective. The C-types are rich in carbon compounds and are less reflective.

Describe and compare the rings of Saturn and Uranus, including their possible origins.

Saturn's rings form a wide and complex system, consisting mostly of particles and pieces of ice, and are highly visible. They may have formed from one or more moons that broke up due to a collision, or are left over from early debris that never coalesced into a moon. T he rings of Uranus are thin and hard to see, consisting mostly of chunks of carbon and hydrocarbons with very little reflectivity. They may also have formed from the breakup of a small moon due to a collision. They may be kept thin by the presence of shepherd moons.

In the context of the giant planets and the conditions in their interiors, what is meant by "rock" and "ice"?

Scientists describe materials in these environments that are composed primarily of iron, silicon, and oxygen as "rock." Similarly, those composed of carbon, nitrogen, and oxygen in combination with hydrogen are described as "ice."

What is the composition of the polar caps on Mars?

Seasonal ice caps are made up of dry ice, or crystals of frozen carbon dioxide.

In addition to the ones mentioned in Exercise 13.3, what is the third, rarer class of asteroids?

The M-types, or metallic asteroids

Give a brief description of the asteroid belt.

The asteroid belt is a region of space between the orbits of Mars and Jupiter containing a few large minor planets and thousands of smaller bodies.

Compare asteroids of the asteroid belt with Earth-approaching asteroids. What is the main difference between the two groups?

The asteroid belt objects have fairly stable orbits. Earth-approaching asteroids have rapidly changing orbits and could potentially collide with our planet.

What are the visible clouds on the four giant planets composed of, and why are they different from each other?

The clouds of Jupiter and Saturn are primarily crystals of frozen ammonia. On Uranus and Neptune, the clouds are composed of methane. The temperatures of these worlds dictate the cloud composition. For Jupiter and Saturn, the temperatures keep methane in a gaseous state, while on Uranus and Neptune, the colder temperatures allow the methane to freeze and condense into clouds.

How do storms on Jupiter differ from storm systems on Earth?

The cyclonic storm features on Jupiter are regions of high pressure, whereas storms on Earth, such as hurricanes, are low-pressure areas.

Why do the upper levels of Neptune's atmosphere appear blue?

The gaseous molecules in Neptune's atmosphere scatter blue light, giving Neptune its color.

Why is it difficult to drop a probe like Galileo? How did engineers solve this problem?

The high speeds involved would guarantee that the probe would burn up on entering the atmosphere. The problem was solved using a heat shield in front of the spacecraft to absorb the heat.

Describe the interior heat source of Saturn.

The mantle of Saturn is still differentiating: The heavier helium is sinking, displacing the lighter hydrogen, which then rises. The "falling" of the helium releases gravitational energy, which heats the interior.

What is the composition of the moon, and how does it compare to the composition of Earth? Of Mercury?

The moon is made almost entirely of silicates (like Earth's mantle and crust). The moon also has an abundance of frozen water. All values for the moon are similar to those of Mercury

Saturn's E ring is broad and thin, and far from Saturn. It requires fresh particles to sustain itself. What is the source of new E-ring particles?

The new particles in the E ring are produced by the geysers on Saturn's moon Enceladus.

What are Earth's core and mantle made of? How do we know?

The outer core is liquid and the inner core is probably solid. It is metallic and compressed at very high densities. This was discovered through differentiation, a process of sorting the main components of planets by density. This suggests the earth was warm enough for the interior to melt, causing metals to sink to the center and create a dense core.

Why were the rings of Uranus not observed directly from telescopes on the ground on Earth? How were they discovered?

The rings of Uranus consist of dark, coal-like particles in narrow bands, making them almost impossible to see from Earth. They were discovered using a flying infrared telescope during the occultation of a star as Uranus passed in front of it.

What evidence is there that Venus was volcanically active about 300-600 million years ago?

There are craters on Venus that are 300-600 million years old, and the surface has not changed so it was only active in that time

Why are asteroids and comets important to our understanding of solar system history?

These objects provide evidence for the conditions that existed in the solar nebula and early solar system.

What is the consequence of Uranus' spin axis being 98° away from perpendicular to its orbital plane?

Uranus is on its side, with the poles alternately facing toward and away from the Sun. Each pole experiences long periods of light and darkness.

Describe the basic internal structure of Mercury.

Very dense planet, most likely a metallic iron-nickel core amounting 60% of its mass, with the rest of the planet being mainly silicates. The core is about the same size as our moon.

Vesta is unusual as it contains what mineral on its surface? What does the presence of this material indicate?

Vesta's surface is partially covered with basalt. Basalt indicates volcanic activity at some point in Vesta's distant past.

What differences did Grove K. Gilbert note between volcanic craters on Earth and Lunar craters?

Volcanic craters on earth are deeper, not as large, and occur at the tops of volcanic mountains. Lunar craters are mountain-rimmed, larger, and have different shapes.

In which domain of living things do you find human kind?

We are under animals in the Eukarya domain of the "tree of life"

How was the rotation rate of Mercury determined?

We had a radar on Earth that transmitted signals toward mercury, the reflected signals were used to calculate its' rotation period.

Summarize the four main hypotheses for the origin of the Moon.

1. The fission theory- The moon was part of the earth and got separated 2. The sister theory- the moon and earth formed together 3. The capture theory- the moon formed elsewhere in the solar system but was captured by the earth 4. They giant impact hypothesis- Earth was struck and material dislodged and formed the moon

List at least three major differences between Pluto and the terrestrial planets.

1. Pluto is much smaller than all the terrestrial planets 2. Its composition is ice and rock as opposed to the composition of rock and metal of the terrestrial planets. 3. Pluto's orbit is highly elliptical and inclined as opposed to the circular orbits near the plane of the ecliptic for the terrestrial planets.

Explain briefly how the following phenomena happen on Earth, relating your answers to the theory of plate tectonics. A. Earthquakes B. Continental Drifts C. Mountain Building D. Volcanic Eruptions E. Creation of the Hawaiian Island Chain

A. Tectonic plates can crash together (pull apart, burrow under another, slide alongside each other, jam together) causing part of Earth's crust to move and quake. B. Tectonic plates can slowly separate the crust, which could cause a continent to be detached from it's parent body of land C. Tectonic plates jam against another, forcing the crust upwards along with deep rock being pushed above the surface. The great pressure from the plates essentially causes the Earth to buckle. D. Volcanoes are found at mid ocean ridges (mountain ranges formed at Earth's mantle at plate boundaries) and along subduction zones E. Hawaiian Island Chain came from "hot spots" where heat is rising from the mantle, it feed volcanoes and as plates shifted a chain of volcanoes formed.

List several ways that Venus, Earth, and Mars are similar, and several ways they are different.

Venus, Earth, and Mars are similar in that they consist of rock and metal for the most part; they are terrestrial planets and all have atmospheres and greenhouse effectAll have volcanic activity.

Describe the differences among primitive, igneous, sedimentary, and metamorphic rock, and relate these differences to their origin.

Igneous rock- any rock that has cooled from a molten state (volcanically produced) Sedimentary Rock- made of fragments of igneous rock or the shells of living organisms deposited by wind or water and cemented together without melting Metamorphic Rock- Produced when high temperatures or pressure alters igneous or sedimentary rock physically or chemically.

What evidence do we have that there was running (liquid) water on Mars in the past? What evidence is there for water coming out of the ground even today?

Images from orbiting spacecraft of runoff channels and outflow channels all show evidence of formation by running water. Several dry basins contain minerals that only form with water. dark streaks that got longer over the course of several days showed spectra of hydrated salts, and may be evidence of saltwater on Mars today.

The mountains on the moon were formed by what process?

Impact craters

What are the principle features of the Moon observable with the unaided eye?

Impact craters and splotches of darker lava flow.

Describe the current atmosphere on Mars. What evidence suggests that it must have been different in the past?

It consists mostly of carbon dioxide, but is very thin, less than 1% of Earth's atmosphere. water on Mars in the past means that the atmosphere was thicker and warmer, or water would have evaporated away very quickly.

With no wind or water erosion of rocks, what is the mechanism for the creation of lunar "soil"?

It is a product of impacts. Impacts break up the lunar surface into small rock fragments, making up the "soil"

Why is Mars red?

Its surface rocks were rusted by oxygen.

Which planet has the strongest magnetic field, and hence the largest magnetosphere? What is its source?

Jupiter has the largest magnetosphere. The large, rapidly spinning, liquid-metallic hydrogen above the core is the source of its magnetic field.

How was Pluto discovered? Why did it take so long to find it?

Pluto was discovered at Lowell Observatory by Clyde Tombaugh. From comparisons of photographs taken several days apart that showed the relative motion of Pluto against a background of stars. Pluto was difficult to find because of its small size and great distance from Earth.

What is the relationship between Mercury's rotational period and orbital period?

The rotation is 2/3 the planet's revolution.

Why does the moon not have an atmosphere?

The super low amount of gravity on the moon allows gas to escape easily, so an atmosphere can't hold.

What is the evidence for a liquid water ocean on Europa, and why is this interesting to scientists searching for extraterrestrial life?

The surface of Europa features jagged blocks of ice that seem to have rotated and collided with one another, which would not likely happen on a solid moon. Long, straight cracks in the crust are also more likely to happen over a liquid subsurface layer than a solid one. Also, a weak magnetic field implies the presence of a liquid layer below the surface. Water means life.

Why are there so many impact craters on our neighbor world, the Moon, and so few on the Earth?

The tectonic plates on Earth are constantly rebuilding the crust, so when an impact happens the crater is covered by new crust being formed via the movement of the tectonic plates. Earth is the only planet with these plates, so on the moon when there's an impact there's no way for the crater to be covered.

What are the main challenges involved in sending probes to the giant planets?

There are many challenges, mainly the huge distances that require many years of flight time. The spacecraft must be reliable and robust to survive the journey. The low temperatures of space require onboard heating so the components don't freeze. The light levels are too low for solar panels to provide enough energy, requiring onboard power systems.

What classification is given to objects such as Pluto and Eris, which are large enough to be round, and whose orbits lie beyond that of Neptune?

These objects are called dwarf planets, and given their location, are also called trans-Neptunian objects (TNOs).

List the possible interactions between Earth's crustal plates that can occur at their boundaries

They can create subduction/rift zones, fault zones/mountains, and volcanoes

Compare the properties of Titan's atmosphere with those of Earth's atmosphere.

Titan's atmosphere is four times denser than Earth's atmosphere at the surface, even though both atmospheres are mostly nitrogen. Both atmospheres have a weather cycle of evaporation from surface liquid, formation of clouds, and precipitation back onto the surface, but Earth's cycle is water-based and Titan's cycle is hydrocarbon-based

Describe two anomalous features of the rotation of Venus and what might account for them.

Venus has a retrograde motion about its axis, opposite to the direction of spin of most planets, and a rotational period longer then any other planets. Scientists think Venus suffered collision with another large body during the formation period of the solar system changing its rotational motion.