Astronomy Test 2

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Homework and Quizzes

Order of Planets

Mercury, Venus, Earth, Mars,Jupiter,Saturn, Uranus, Neptune

rank the order of the planets highest to lowest temp

For some planets, temperature correlates with distance from the Sun: the closer to the Sun, the hotter the planet. This is not always the case, because a planet's temperature also depends on its reflectivity and on the strength of its greenhouse effect (if any). For example, the greenhouse effect gives Venus a higher average temperature than Mercury, even though Venus is nearly twice as far from the Sun.

rank the planets from shortest to longest orbital periods

Recall that the time it takes a planet to orbit the Sun is called its orbital period, and that Kepler's third law tells us that orbital period increases with distance from the Sun. That is why the ranking order for orbital period is the same as the ranking order for distance from the Sun.

rank jupiter, mars, earth, and mercury by the most to least amount of moons

Jupiter has many moons as a consequence of its formation, in which moons formed in a disk of material surrounding it and its extended atmosphere at the time allowed it to capture numerous small bodies into orbit. Mars has two very small moons that it presumably captured at a time when it, too, had an extended atmosphere. Earth's single but surprisingly large moon is thought to have formed as a result of a giant impact. Mercury (and Venus) have no moons.

Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestrial planets?

Terrestrial planets will likely be located nearer the planetary system's star than any jovian planets.

Compared to terrestrial planets, jovian planets are __________.

more massive and lower in average density

The dwarf planet Eris was discovered in 2005, orbiting the Sun at an average distance about twice that of Pluto. In which of the following ways do Pluto and Eris differ from the terrestrial and jovian planets in our solar system?

1.Both Pluto and Eris are smaller than any of the terrestrial planets. 2. Both Pluto and Eris travel in more elliptical orbits than any of the terrestrial or jovian planets. 3.Both Pluto and Eris are less massive than any of the terrestrial or jovian planets.

What substances were found within the inner 0.3 AU of the solar system before planets began to form?

rocks, metals, hydrogen compounds, hydrogen, and helium, all in gaseous form

Where would you expect terrestrial planets to form in the solar nebula?

anywhere between 0.3 AU and the frost line (Terrestrial planets are made mostly of metal and rock and therefore formed in the region in which it was cool enough for metal and rock to condense but still too warm for hydrogen compounds to condense into ices. This means the region between the rock/metal condensation line at 0.3 and the frost line)

The jovian planets are thought to have formed as gravity drew hydrogen and helium gas around planetesimals made of __________.

rocks, metals, and ices (Because ices could condense only beyond the frost line, we expect jovian planets to form only beyond the frost line)

Qualities of the formation of terrestrial planets

1. accreted from planetesimals of rock and metal 2. surfaces dramatically altered during heavy bombardment

qualities of the formation of jovian planets

1. large moons formed in surrounding disks of material 2. ejected icy planetesimals that are now Oort cloud comets 3. formed in a region of the solar system with lower orbital speeds 4. formed in regions cold enough for water to freeze 5. accreted from icy planetesimals

state the relationship between the dopler shift of a planet and its distance from the sun/mass

same as gravitational force, shorter the orbital distance and higher the mass, stronger the force/dopler

T/F: A planet's size can be determined by observing its transit across a star.


T/F: Most of the planets discovered around other stars have masses comparable to the terrestrial planets in our own solar system.


T/F: Astronomers have discovered more extrasolar planets around other stars than the number of planets in our own Solar System.


T/F:Based on our theory of how our own solar system formed, we would expect that other solar systems would be quite common.


T/F: All planets orbit the Sun in the same direction (counterclockwise as viewed from above Earth's North Pole).


T/F:Pluto is the largest solar system object beyond the orbit of Neptune


T/F: All four of the giant outer planets - Jupiter, Saturn, Uranus, and Neptune - have rings.


Rank the terrestrial planets based on their expected cooling rates, from fastest cooling to slowest cooling.

(Mercury, Mars, Venus, Earth) Smaller planets cool faster than larger planets

Rank Earth, Mars, and Mercury based on the amount of time the surface of the planet has had a moderate to high level of volcanic/tectonic activity, from longest to shortest.

Earth, Mars Mercury. (Earth still has a great deal of tectonic activity today, Mars has much less ongoing tectonic activity, and Mercury probably has very little or no ongoing tectonic activity. Tectonic activity requires interior heat, so planets that cool faster lose their tectonic activity in a shorter time.)

examples of volcanism

1. Big Island of Hawaii 2. Smooth surfaces of the lunar maria 3. Mar's Olympus Mons

example of cratering

old surface features of the lunar highlands

example of erosion

Earth's Grand Canyon

example of tectonics

1. current location of Earth's continents 2. Mercury's many long, tall cliffs 3. Mar's Valles Marineris

the slowly increasing distance between South America and Africa is due to _______

seafloor spreading

Old Faithful aquires its energy from a ___

hot spot

layered ___ exposed by erosion can be seen when looking at the Grand Canyon

sedimentary rock

Australia is composed of relatively old and thick_____

continental crust

the extremely deep ocean Marianas Trench is a result of ____


___ found in Atlantic ocean between North America and Europe is composed of dense and relatively young rock

seafloor crust

the earthquakes that occur in Southern California generally occur above a ___


Assuming that features you see on Mars are similar to features found on Earth, what would lead you to suspect about water on Mars?

Surface water only exists as frozen ice.

Which of the following Mars surface features provides dramatic evidence that volcanism has played a role in shaping the surface of Mars?

Olympus Mons

On Mars you can see the "Southern Highlands," which geologic processes are most clearly evident?

impact cratering and erosion

The energy that warms Earth's surface comes primarily in the form of __________.

visible light from the Sun

Earth's temperature remains fairly steady, which means that Earth must return the same amount of energy to space that it receives from the Sun. In what forms does Earth return most of this energy to space?

1. visible light reflected by clouds 2. infrared light emitted by the surface and atmosphere 3. visible light reflected by the surface

Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, make Earth warmer than it would be otherwise because these gases __________.

absorb infrared light emitted by the surface (Although the absorbed infrared light is quickly reemitted, it is reemitted in a random direction. As a result, greenhouse gases tend to slow the escape of infrared light from Earth to space, so that there is more heat (which means more energy) in the atmosphere than there would be if the infrared light escaped directly to space)

According to scientists, the naturally occurring greenhouse effect makes Earth about 31 warmer than it would be if there were no greenhouse gases in our atmosphere. How do scientists "know" what Earth's temperature would be without greenhouse gases?

They calculate this temperature from Earth's reflectivity and distance from the Sun.

T/F: Earth is the only planet with an ozone layer in its atmosphere


T/F:earth has a higher average temperature than mars


T/F:Mercury is much hotter than the moon


What is support for the claim that greenhouse gases make a planet warmer than it would be otherwise?

Venus has a higher average temperature than Mercury.(The fact that Venus is hotter than Mercury despite being nearly twice as far from the Sun tells us that its thick carbon dioxide atmosphere must warm it significantly)

T/F:We should expect an increase in the greenhouse gas concentration to lead to global warming.


Rank the terrestrial planets from left to right based on the atmospheric pressure at the surface, from highest to lowest.

Venus, Earth, Mars, Mecury (Mercury has essentially no atmosphere and no pressure. Earth's atmospheric pressure is more than 100 times that of Mars, and Venus's atmospheric pressure is about 90 times that of Earth.)

Rank the terrestrial planets from left to right based on the total amount of gas in their atmospheres, from most to least.

Venus, Earth, Mars, Mercury (more atmospheric gas generally means more pressure)

characteristics of Venus's atmosphere

1. sulfuric acid clouds 2. almost no wind ( b/c of its slow rotation rate)3. runaway greenhouse effect (b/c of its distance from the sun)

characteristics of Earth's atmosphere

1. composed primarily of nitrogen 2. ultraviolet- absorbing atmosphere (b/c of the oxygen in the atmosphere, which at high altitudes forms molecules of ultraviolet- absorbing ozone)

characteristics of Mars's atmosphere

1. extremely lowe density atmosphere 2. global dust storms

In general, what kind of terrestrial planet would you expect to have the thickest lithosphere?

a small planet

Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?


What do we conclude if a planet has few impact craters of any size?

Other geological processes have wiped out craters.

How many of the five terrestrial worlds are considered "geologically dead"?


Which of the following is a strong greenhouse gas?

water vapor

Which describes our understanding of flowing water on Mars?

It was important once, but no longer.

T/F:The density of Mars is very similar to that of the other terrestrial planets.


Which three worlds have almost identical densities?

Mercury, Venus, and Earth

Which of these gets so bright as to be seen in daylight at times?


One of the effects of Mercury's very slow spin is

extreme variations in its surface temperature.

T/F:Venus' surface temperature cools off at night, much like Mercury's does.


T/F:Venus' rotation period is longer than its period of revolution around the Sun.


Which planet shows the widest range of surface temperatures between day and night?


T/F:Mars appears red in color because of refraction of light by its atmosphere, much like the color of the totally eclipsed Moon.


The main constituent of the martian atmosphere is

Carbon Dioxide

The atmospheric pressure on Venus:

is much higher than on Earth

How does Mercury's rotation relate to the Sun?

Its rotation rate is 2/3 as long as its year, due to tidal resonances.

T/F: Atmospheric pressure on Mars is roughly half that of Earth's at sea level.


T/F:The surface temperature of Venus is 750K, even hotter than Mercury.


What is the main constituent of the atmosphere of Venus?

Carbon Dioxide

T/F:Running water played a major role in shaping Mars in ancient times.


T/F:Mercury has an unusually small core.


T/F:The seasonal polar caps on Mars, which grow and shrink over the year, are primarily carbon dioxide.


The scarps on Mercury were probably caused by

the crust cooling and shrinking.

T/F: Mercury's rotation and revolution are an example of a 3:2 resonance.


Why are Mars' seasons more extreme than those of the earth?

1.Mars' seas dried up long ago. 2.Mars' orbit is more eccentric than our almost circular one. 3.Mars' weather is driven by evaporation from the polar ice in its summer.
4.Mars' axial tilt is slightly more than our 23.5 degrees.

What statement sums up the composition among the four jovian planets?

Jupiter and Saturn have compositions that are fairly different from the compositions of Uranus and Neptune (Jupiter and Saturn are made mostly of hydrogen and helium, while Uranus and Neptune are primarily made of hydrogen compounds such as water (H2O), methane (CH4), and ammonia (NH3).)

Which of the following statements best explains why the densities of Uranus and Neptune are higher than those of Jupiter and Saturn?

They have a higher proportion of hydrogen compounds and rock.

Which of the following best explains why Jupiter's density is higher than Saturn's?

Jupiter is more massive than Saturn

Based on the leading scientific theory of solar system formation, which of the following statements best explains why Uranus and Neptune have a significantly different composition and higher density than Jupiter and Saturn?

Jupiter and Saturn captured more gas from the solar nebula than Uranus and Neptune.

Rank the jovian planets and earth from smallest to largest diameter

Earth, Neptune, Uranus, Saturn, Jupiter

Rank the jovian planets and earth left to right based on their mass, from lowest to highest.

Earth,Uranus, Neptune, Saturn, Jupiter

Characteristics of all jovian planets

1. approximately 10 Earth- mass core 2. strong atmospheric wind and storms 3. orbited by rings of rock and ice 4. magnetic fields stronger than Earth

T/F: Do the Jovian planets have a solid surface?


characteristics of uranus and neptune

1. Blue color because of methane 2. composed mostly of hydrogen compounds

characteristics of jupiter and saturn

1. interior is mostly liquid or metalic hydrogen 2. composed mostly of hydgrogen and helium

Io experiences tidal heating primarily because __________.

Io's elliptical orbit causes the tidal force on Io to vary as it orbits Jupiter

From Part A, Io's elliptical orbit is necessary to its tidal heating. This elliptical orbit, in turn, is a result of the orbital resonance among Io, Europa, and Ganymede. This orbital resonance causes Io to have a more elliptical orbit than it would otherwise, because __________.

Io periodically passes Europa and Ganymede in the same orbital position

We cannot see tidal forces or tidal heating; rather, we predict that they must occur based on the orbital characteristics of the moons. What observational evidence confirms that tidal heating is important on Io?

active volcanoes on Io

moons of Jupiter.

lo, Europa, Ganymede

The orbital resonance also gives Europa an elliptical orbit, so it also experiences tidal heating. However, Europa experiences less tidal heating than Io, because Europa __________ than Io.

is farther from Jupiter

We now know of many Jupiter-size planets around other stars. Suppose that future observations show that one of these planets has two orbiting moons. What additional information, if any, would we need to decide whether these moons experience tidal heating?

their orbital periods (We expect tidal heating to be possible only if there is an orbital resonance that helps maintain an elliptical orbit. An orbital resonance occurs when one moon's orbital period is a simple fraction of the other's, such as 1/2 or 1/3 or 1/4.)

characteristics of Io

1. volcanos currently errupting 2. hot, glowing lava visible in some photos 3. source of ionized gas in the donut shaped charged particle belt around Jupiter

characteristics of Europa

1. ice covered surface with few impact craters 2. surface features provide evidence of subsurface liquid oceans

how many moons orbit pluto


characterisitcs of Ganymede

1. largest moon in the solar system 2. heavilty cratered terrain adjacent to much younger terrain

Why does Neptune appear blue and Jupiter red?

Methane in Neptune's atmosphere absorbs red light.

Why is Jupiter denser than Saturn?

Its higher mass and gravity compress its interior.

Some jovian planets give off more energy than they receive because of

ongoing contraction or differentiation.

Why is Io more volcanically active than our moon?

Io has a different internal heat source.

What is unusual about Triton?

It orbits its planet backward.

T/F: The zonal flows giving rise to the belts and zones are similar to the jet streams in our own stratosphere.


Which two jovians have magnetic field tilts that are not along their rotation poles?

Uranus and Neptune

Alternating zones of rising and sinking gas in Jupiter's atmosphere _____

create light and dark bands.

In terms of axial tilt, which of the jovians shows us the largest inclination?


T/F: Jupiter's magnetic field is much stronger than Earth's, and has a magnetic tail that extends beyond the orbit of Saturn.


Uranus was discovered

less than 250 years ago

T/F: Jupiter's atmosphere looks uniform and calm, with no visible detail.


T/F: Like the discovery of Uranus, the finding of Neptune was accidental.


What is true of Jupiter's magnetosphere?

It has a tail that extends at least to Saturn's orbit.

Small deviations in a planet's orbital motion _____

imply the nearby presence of a massive body.

T/F: All four jovians spin faster than any of the terrestrials.


T/F: The axial tilts of Uranus and Neptune are similar.


Compared to Saturn, Jupiter is about

three times more massive and denser.

T/F: William Herschel was the discoverer of Uranus.


Which three played a role in the finding of Neptune?

Adams, Leverrier, and Galle

Essentially, the Great Red Spot is ____

a large cyclonic storm (hurricane).

T/F: Saturn is less dense than water.


The reason the jovian planets lost very little of their original atmosphere is due to their _____

large mass

What would Jupiter have needed to be a star?

enough more mass to make the planet hotter

T/F: Differential rotation is when a planet's equator and polar regions rotate at different rates.


characteristics of comets

1. form a coma when near the sun 2. visible in the sky as a fuzzy patch that rises and sets with the stars 3. most are located in the Oort cloud or the kuiper belt

characteristics of meteors

1. dust particles entering Earth's atmosphere at high speeds 2. visible in the sky as a bright streak of light for only a few seconds

characteristics of asteroids

1. compositions similar to that of terristrial planets 2. typically orbit the sun at about 3 AU

A comet entering the inner solar system from afar will __________.

form a coma and some time later form a tail (The coma consists of dust and gas released from the comet as it is heated by the Sun. Only later, as the solar wind affects the comet, does material from the coma extend out to form a tail)

During the time that a comet passes through the inner solar system, the comet can appear quite bright because __________.

sunlight reflects off the comet's tail and coma

A comet's plasma tail always points directly away from the Sun because __________.

of pressure exerted by the fast-moving charged particles in the solar wind (The plasma tail is always directed away from the Sun because it is pushed outward by the solar wind)

about a trillion comets are thought to be located far, far beyond pluto in the ____

oort cloud

the bright spherical part of a comet observed when it is close to the sun is the ____


a comet's _____ stretches directly away form the sun

plasma tail

a comet's _____- is the frozen portion of a comet


particles ejected from a comet can cause a ____ on Earth

meteor shower

the ____ extends from about beyond teh orbit of neptune to about twice the distance of neptune from the sun

Kuiper belt

length of a tail of a comet during its orbit of the sun

The length of the tail depends primarily on the distance of the comet from the Sun. It is longer when the comet is closer to the Sun and shorter (or nonexistent) when the comet is farther from the Sun.

The asteroid belt lies between the orbits of ____

Mars and Jupiter

Jupiter nudges the asteroids through the influence of ____

orbital resonances

Did a large terrestrial planet ever form in the region of the asteroid belt?

No, because Jupiter prevented one from accreting

distance of objects in the solar system from the sun from closest ot farthest

The asteroid belt is located between Mars and Jupiter. The Trojan asteroids share Jupiter's orbit of the Sun. The Kuiper belt is a region beginning just beyond the orbit of Neptune. The Oort cloud is located far beyond the orbits of the planets.

Rank objects in the solar system by distance from the Sun at which they are presumed to have formed, from nearest to farthest.

Although Oort cloud comets are now located far beyond the Kuiper belt, they are thought to have formed in the region of the jovian planets. They were then "kicked out" to their current orbits by gravitational encounters with the jovian planets.

What has the most elliptical and tilted orbits between asteroids, kuiper belt comets, and oort cloud comets?

oort cloud comets

What is true about asteroids, Kuiper belt objects, and Oort cloud objects?

Objects in the asteroid belt and Kuiper belt orbit the Sun in nearly the same plane as the planets, but objects in the Oort cloud do not.

What does Pluto most resemble?


According to current evidence, Pluto is best explained as ______.

a large member of the kuiper belt

What best describes the size of the largest asteroid, Ceres?

it is a little less than half the diameter of our moon

Gaps in the asteroid belt (often called Kirkwood gaps) are caused by ________.

orbital resonances with jupiter

When we see a meteor shower, it means that ________.

Earth is crossing the orbit of a comet

Why won't Pluto collide with Neptune?

Pluto orbits the Sun exactly two times for every three Neptune orbits, which ensures they never come close together.

The discovery of Eris ________.

was not surprising, because other Kuiper belt objects approaching the size of Pluto had already been discovered

What is Charon?

The largest of Pluto's three known moons

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