Chapter 6

How many of the planets orbit the Sun in the same direction as Earth does?..

all

Which lists the major steps of solar system formation in the correct order?..

collapse, condensation, accretion

Leftover ice-rich planetesimals are called..

comets

Which of the following did NOT occur during the collapse of the solar nebula?...

concentrating denser materials nearer the sun

Briefly describe the 4 major features of our solar system that provide clues to how it formed.

1.Patterns of motion among large bodies: the Sun, planets, and large moons generally orbit and rotate in a very organized way 2.Two major types of planets: The 8 planets divide clearly into two groups: the small rocky planets that are close together and close to the Sun and the large, gas rich planets that are farther apart and farther from the Sun. 3.Asteroids and comets: Between and beyond the planets, vast numbers of asteroids and comets orbit the Sun, some are large enough to qualify as dwarf planets. The locations, orbits, and compositions of these asteroids and comets follow distinct patterns. 4.Exceptions to the rules: the generally orderly solar system also has some notable exceptions. For example, among the inner planets only Earth has a large moon, and Uranus is tipped on its side. A successful theory must make allowances for exceptions even as it explains the general rules.

T/F Neptune orbits the Sun in the opposite direction of all the other planets.

False

T/F When scientists say that our solar system is about 4 ½ billion years old, they are making a rough estimate based on guesswork about how long it should have taken planets to form.

False

T/F Asteroids are made of essentially the same materials as the terrestrial planet.

True

Planetary orbits in our solar system are...

fairly circular and in the same plane

T/F Moons cannot have atmospheres, active volcanoes, or liquid water

false

T/F Saturn is the only planet in the solar system with rings.

false

Jupiter's main ingredient

hydrogen and helium

The solar nebula was 98%...

hydrogen and helium

Whats unusual about our Moon

its large relative to the planet it orbits

T/F On average, Venus has the hottest surface temperature of any planet in the solar system.

true

What are asteroids and comets, and how did they come to exist? How and why are they different?

Asteroids: are the rocky leftover planetismals of the inner solar system. Comet: are the icy leftover planetismal of the outer solar system. Evidence that asteroids and comets are leftover planetesimals comes from analysis of meteorites, spacecraft visits to comets and asteroids, and theoretical models of solar system formation. Other leftover or lost planetesimals were flung deep into space or they create impact craters sometimes..

Are there any exceptions to the rule that planets rotate will small axis tilts and in the same direction as they orbit the Sun?

Exception: venus and uranus

What is the leading hypothesis for the Moon's formation? What evidence supports this hypothesis?

Giant Impact: a Mars size object hit Earth at a speed and angle that blasted Earth's outer layers into space. Evidence Support: 1. Moon's overall composition is quite similar to that of Earth's outer layers-just as we should expect if it were made from material blasted away from those layers. 2. The Moon has a much smaller proportion of easily vaporized ingredients (water) than Earth-heat of impact would have vaporized the ingrediants.

Describe three key processes that led the solar nebula to rake the form of a spinning disk. What evidence supports this scenario?

Heating: temperature increased. Such heating represents energy conservation in action. Spinning: rotated faster and faster, conservation of angular momentum. Flattening: made from collisions between particles in a spinning cloud. Collisions between clumps of material in highly elliptical orbits reduce their eccentricities, making their orbits more circular. Computer models agreed with this....

What was the heavy bombardment and when did it occur?

Heavy Bombardment: the collisions occurred in the 1st few hundred million years of our solar system's history. Every world in our solar system must have been pelted by impacts during the heavy bombardment and most of the craters on the Moon and other worlds date from this period.

Describe the four categories of material in the solar nebula by their condensation properties and abundance. Which ingredients condensed inside and outside the frost line?

Hydrogen and helium gas: these gases never condense in interstellar space. Hydrogen compounds: Materials such as water, methane, ammonia, can solidify into ices at low temperatures. Rock: Rocky material is gaseous at high temperature but condenses into solid form at temperatures between about 500k and 1300 k, depending on the type of rock. Metals: metals such as iron, nickel, aluminum are also gaseous at high tempreatures but condense into solid form at temperatures between about 1000K to 1600 K. Only the hydrogen compounds were able to condense into ice beyond the frost line (which lays between mars and Jupiter).

Briefly describe the layout of the solar system as it would appear from beyond the orbit of Neptune.

It would not look like much. The Sun and planets are all quite small compared to the distances between them. They would only be pinpoints of light, and even the Sun would be just a small bright dot in the sky.

What is the nebular theory, and why is it widely accepted by scientists today?

Nebular theory: Immanuel Kant proposed that our solar system formed from the gravitational collapse of an interstellar cloud of gas. Cloud in Latin was nebula. Accepted by scientists because they found that the nebular hypothesis offered natural explanations for all four general features of our solar system, so much evidence has accumulated that it has achieved the status of a scientific theory. The opposing theory was called close encounter hypothesis: planets formed from blobs of gas that had been gravitationally pulled out of the Sun during the near-collision.

**Briefly explain the technique of radiometric dating. What is a half-life? How do we use radiometric dating to determine the age of the solar system?

Radiometric dating: This is the method we use to measure the age of a rock. It relies on careful measurements of the proportions of various isotopes in the rock. Half-time: The time it would take for half of the parent nuclei in the collection to decay or the time if takes for half of the nuclei in a given quantity of a radioactive substance to decay. We can validate the 4 ½ billion year radiometric age for the solar system as a whole by comparing it to an age based on detailed study of the Sun. The model ages are not nearly as precise as radiometric ages, but they confirm that the Sun is between about 4 and 5 billion years old.

A solar system has 12 planets that all orbit the star in the same direction and in nearly the same plane. The 15 largest moons in this solar system orbit their planets in nearly the same direction and plane as well. However, several smaller moons have highly inclined orbits around their planets.

Reasonable but: Most planets and moons do indeed lie in the same plane, and orbit in the same direction. However, It would be highly unusual to find moons with a high inclination of their orbits- all moons always lie on the same plane as the other moons.

A solar system has 5 terrestrial planets in its inner solar system an 3 jovian planets in its outer solar system.

Reasonable, because Jovian planets consist of hydrogen helium and hydrogen compounds that can be solidified beyond the frost line or outer solar system .?

A solar system has several terrestrial planets and several larger planets made mostly of ice. (Hint: What would happen if the solar wind started earlier or later than in our solar system).

Reasonable, because larger planets are usually like Jovian planets, which are cold. It may be possible for the formation process of jovian planets to be interrupted by solar wind

A solar system has four Earth-sized terrestrial planets. Each of the four planets has a single moon that is nearly identical in size to Earth's moon.

Reasonable, that's like our own solar system.

Radiometric dating of the oldest meteorites from another solar system shows that they are a billion years younger than rocks from the terrestrial planets of the same system.

Reasonable, there is no reason that other solar systems should be the same age as ours.

How was the formation of jovian planets similar to that of the terrestrial planets? How was it different? Why did the Jovian planets end up with many moons?

Similar: The formation was similar due to accretion which is the process of small solid rock "seed" as they grew into planets and once the gases came from a solid material. The two also have planetesimals which are "pieces of planets". Different: As each jovian planet is wrapped around its own disk of gas but terrestrials don't have this. Moons: Because they were captured in the planetary orbit when they lost energy to drag in the extended disks of gas that surrounded these planets as they formed. they would have been slowed by the friction with gas. It slowed planetesimals orbital energy enough to make it an orbiting moon.

What do we mean by the solar nebula? What was it made of, and where did it come from?

Solar Nebula: the particular cloud of gas from which our solar system was born. Big Bang was produced by two element which were hydrogen and helium. But then heavier elements were produced later by massive stars. The heavy elements then mixed with other interstellar gas to form new generations of stars, the overall chemical composition of the universe remain mostly hydrogen and helium.

A solar system has 10 planets that all orbit the star in approx.. the same plane. However, five planets orbit in one direction (counterclockwise), while the other 5 orbit in the opposite direction (clockwise).

Surprising because I think it would be more likely for them to collide, since their approx. on the same plane.

A solar system has 4 large Jovian planets in its inner solar system and seven small terrestrial planets in its outer solar system.

Surprising because, Jovian planets aren't usually in inner solar systems they need to be where its cold enough for the them. Terrestrial planets cannot be in outer space because its too cold out there for them.

A solar system has six terrestrial planets and four jovian planets. Each of the six terrestrial planets has at least 5 moons, while the jovian planets have no moons at all.

Surprising, because Jovian planets are the ones who are supposed to have more moons because they have more gravitational force since they are gaseous planets, hence holding more moons. Terrestrial planets couldn't.

A solar system has many rocky asteroids and many icy comets. However, most of the comets orbit in the inner solar system, while the asteroids orbit in far-flung regions much like the Kuiper belt and Oort cloud of our solar system.

Surprising, because icy comets usually form in the outer solar system where it's colder, asteroids are usually inner and rocky.

What are the basic differences between terrestrial and Jovian planets? Which planets fall into each group?

Terrestrial planets are more "Earth like" which are small and dense. Has rocky surfaces and an abundance of metal in their cores. These planets have few moons and no rings. Mercury, Venus, Earth and Mars. Also our moon is considered a terrestrial world. Jovian Planets are more "Jupiter like" which are larger in size, lower in average density. They have rings and many moons, they also lack solid surface. Made mostly of hydrogen, helium, and hydrogen compounds (water methane). Jupiter, Saturn, Uranus, and Neptune. Often referred to as "gas giants," QUIZ!

Briefly describe the process by which terrestrial planets are thought to have formed.

Terrestrial planets formed inside the frost line, where accretion allowed tiny, solid grains of metal and rock to grow into planetesimals that ultimately merged to make the planets we see today

A solar system has several planets similar in composition to the jovian planets of our solar system but similar in mass to the terrestrial planets of our solar system.

This would be surprising. We know of no process by which to make a jovian planet-with abundant hydrogen and helium gas-without 1st making a massive core of hydrogen compounds. It may be possible to have planets similar in size to terrestrial planets but made of hydrogen compounds.