Mastering Astronomy Ch 6

Saturns many moons affect its rings through

orbital resonances

what types of evidence for recent or ongoing geological activity have been observed on one or more jovian moons?

river valleys feeding into surface lakes of very cold liquids surfaced with very few impact craters active volcanoes ice crystals being sprayed out into space

Planetary Motions for no Jovian planets

solid surface under a thick atmosphere

the odds of a 100-meter asteroid hitting the Earth over the course of one year is approximately __________.

somewhat less than 1 in 1000

Geological Characteristics of Europa

surface features provide evidence of a subsurface liquid ocean ice covered surface with few impact craters

When a comet passes near the Sun, part of it takes on the appearance of a large, bright ball from which the tail extends. This part is called _________.

the coma

Which of the following can contribute to explaining why jovian moons are sometimes much more geologically active than terrestrial worlds of similar (or smaller) size?

tidal heating, ice-rich composition

Distinguishing Characteristics of Asteroids

typically orbit the Sun at approx. 3AU compositions similar to that of the terrestrial planets

Distinguishing Characteristics of Meteors

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

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?

we need to know their orbital periods

the minimum size of an object that could cause a mass extinction is a little less than _____.

10 km

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

No, because there was never enough mass there

This moon of Neptune orbits "backward" compared to Neptune's rotation.

Triton

T or F Some of the moons of the Jovian planets have significant atmospheres

True

T or F To measure the mass of an astronomical object, one can observe the orbital period and distance of a companion

True

The asteroid belt lies between the orbits of ______

Mars and Jupiter

Rank from distance from the Sun at which they are presumed to have formed, nearest to farthest a typical asteroid in the asteroid belt, a typical Oort cloud object, and a typical Kuiper belt object

Nearest- a typical asteroid in the asteroid belt a typical Oort cloud object Farthest- a typical Kuiper belt object

Planetary Motions for Uranus and Neptune only

composed mostly hydrogen compounds blue color because of methane

Planetary Motions for Jupiter and Saturn only

composed mostly of hydrogen and helium interior is mostly liquid or metallic hydrogen

Which of the following best describes the internal layering of Jupiter, from the center outward?

core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; cloud layer

Geological Characteristics of Ganymede

heavily cratered terrain adjacent to much younger terrain largest moon in the solar system

Geological Characteristics of Io

hot, glowing lava visible in some photos volcanoes currently erupting source of ionized gas in the donut shaped charged particle belt around Jupiter

The largest moon in the solar system, this moon has some regions that are heavily cratered other regions that have very few craters.

Ganymede

Rank from closest to farthest from the Sun a typical asteroid in the asteroid belt, a typical Oort cloud object, and a typical Kuiper belt object

Closest- a typical asteroid in the asteroid belt a typical Kuiper belt object Farthest- a typical Oort cloud object

which statement below most accurately describes the impacts we should expect on Earth during the coming year?

Earth will be hit by at least one object a few meters in diameter, along with many smaller objects.

Orbits Saturn and has been observed to be spraying fountains of ice crystals into space.

Enceladus

This moon of Jupiter has an icy surface with very few impact craters, suggesting that craters have been covered by upwelling water.

Europa

T or F No spacecraft has landed on a Jovian planet moon

False

The most volcanically active world in the solar system

Io

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, Europa and Ganymede periodically return to the same orbital positions, creating the same gravitational tugs

Why is Newton's version of Kepler's third law so useful to astronomers?

It can be used to determine the masses of many distant objects.

Which statement about Io is true?

It is the most volcanically active body in our solar system.

What is unusual about Triton?

It orbits its planet backwards

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 than Jupiter and Saturn?

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

What explains why Jupiters density is higher than Saturns?

Jupiter is more massive than Saturn

The impact of a 100-meter object will not cause "widespread" devastation, but it could still kill millions of people if it struck a major city. you found that the probability of such an impact in any single year is only 1 in 1000. Suppose we learn that it has already been 1200 years since the last such impact. What would that tell us?

Nothing; we would still presume that the chance of such an impact during the next year is 1 in 1000.

What correctly describes the motion of the particles in Saturns rings?

Particles in the inner rings orbit Saturn at a faster speed than particles in the outer rings

Rank from shortest to longest orbital period around the Sun a typical asteroid in the asteroid belt, a typical Oort cloud object, and a typical Kuiper belt object

Shortest- a typical asteroid in the asteroid belt a typical Kuiper belt object Longest- a typical Oort cloud object

A rock found on Earth that crashed down from space is called _________.

a meteorite

Can you identify a trend in jovian planet densities with mass or distance from the Sun?

There is no clear trend in the densities with mass or distance

How do typical wind speeds in Jupiter's atmosphere compare to typical wind speeds on Earth?

They are much faster than hurricane winds on Earth.

What statement best explains why the densities of Uranus and Neptune are higher than that of Saturn, even though Saturn is much more massive?

They have a higher proportion of hydrogen compounds and rock.

What is the relevance of tidal heating to the possibility of life on jovian moons?

Tidal heating can lead to subsurface zones of liquid water

The only moon in the solar system with a thick atmosphere, it also has lakes of liquid methane and ethane.

Titan

Which of the following statements best describes the general pattern of composition among the four jovian planets?

Uranus and Neptune contain relatively more rock and hydrogen compounds than Jupiter and Saturn.

What is the probability that an object 100 meters in diameter will hit Earth during the coming year?

about 1 in 1000

an object 10 kilometers across hits Earth __________.

about once ever 100 million years

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

Planetary Motions all four Jovian planets

approx 10 Earth-mass core strong atmospheric winds and storms orbited by rings of ice and rock magnetic field stronger than Earths

In light of what we know about geological activity on the terrestrial worlds, why might it seem surprising to find geological activity on jovian moons?

because they are far from the Sun

The asteroid belt is located _____

between the orbits of Mars and Jupiter

Distinguishing Characteristics of Comets

form a coma when near the Sun most are located either in Kuiper belt or Oort cloud visible int he sky as a fuzzy patch of light that rises and sets with the stars

Which direction do a comet's dust and plasma tails point?

generally away from the Sun

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

it is farther from Jupiter

Io experiences tidal heating primarily because __________.

its elliptical orbit causes the tidal force to vary as Io orbits Jupiter

Saturns rings look bright because _______

light from the Sun reflects off the material in the rings

Saturns rings are composed of ______

lots of individual particles of ice and rock

What atmospheric constituent is responsible for the blue color of Uranus and Neptune?

methane