Astronomy Chapter 4 Flashcards

Questions and Answers

What must a theory of the formation of the solar system explain?

The orderly patterns of motion of objects, why planets fall into two major categories (terrestrial and jovian), why comets reside in the Kuiper belt and Oort cloud, and the exceptions to the general rules.

Which of the following is not a problem for the close encounter hypothesis for the origin of the planets?

Gravitational influences

Orbital stability

Collision dynamics

None of the above (correct)

What is the origin of the elements that made up the protoplanetary nebula?

They were formed inside stars or supernovae that exploded before the solar system formed.

Why was the protoplanetary nebula flat?

It flattened as a result of collisions between particles in the nebula. Signup and view all the answers

Which processes did not contribute to orderly motions in the solar system?

Hotter temperatures closer to the Sun Signup and view all the answers

List the ingredients of the solar nebula in order of increasing abundance.

Metals, rocks, hydrogen compounds. Signup and view all the answers

Why are the planets closest to the Sun more dense than those farther from the Sun?

Only dense materials could condense close to the Sun. Signup and view all the answers

Where did hydrogen and helium gas condense in the protoplanetary nebula?

Nowhere. Signup and view all the answers

How did the small particles that condensed in the solar nebula accrete to grow into planetesimals?

They collided gently and stuck together through electrostatic forces. Signup and view all the answers

How did the formation of jovian planets differ from the formation of terrestrial planets?

The jovian planetesimals became large enough to gravitationally capture hydrogen and helium from the nebula. Signup and view all the answers

What condensed beyond the frost line?

All of the above Signup and view all the answers

Why does the Sun rotate slowly today?

The Sun transferred angular momentum to charged particles in the solar wind. Signup and view all the answers

Why did planet formation eventually end?

The solar wind removed the remaining nebular gas. Signup and view all the answers

What happened to most of the mass originally in the asteroid belt?

Some of it crashed into the inner planets while some was ejected from the solar system. Signup and view all the answers

Why do some of Jupiter's moons orbit in the opposite direction of Jupiter's rotation?

They are captured planetesimals that encountered Jupiter in such a way that they ended up orbiting backward. Signup and view all the answers

Which features of the solar system can be explained by giant impacts?

The existence of Earth's large moon. Signup and view all the answers

Which characteristics of the solar system would we not necessarily expect to find around other stars?

A terrestrial planet with a large moon. Signup and view all the answers

Radiometric dating can be used to determine the amount of time since what?

A rock most recently solidified. Signup and view all the answers

How old are the oldest meteorites?

4.55 billion years. Signup and view all the answers

How do we verify the validity of radiometric dating?

Some archeological artifacts have dates on them, and we use multiple radiometric techniques to see if the same ages are found. Signup and view all the answers

Why do we think that the solar system formed from a rotating, collapsing gas cloud that ended up as a disk orbiting the Sun?

All of the above Signup and view all the answers

What is the primary physical law responsible for the heating of the solar nebula as it collapsed?

Conservation of energy. Signup and view all the answers

What is the primary physical law responsible for the increased rotation rate of the solar nebula as it collapsed?

Conservation of momentum. Signup and view all the answers

Why do we think the inner (terrestrial) planets became more dense than the outer planets?

The inner part of the solar nebula was so hot that only dense metals and rocks were able to accrete there. Signup and view all the answers

What do we think the composition of the solar nebula was?

About 98% hydrogen and helium, and 2% heavier elements. Signup and view all the answers

Study Notes

Solar System Formation Theories

A successful solar system formation theory must explain the motion patterns of celestial objects and categories of planets (terrestrial vs. jovian).
It should clarify why comets are found in the Kuiper belt and Oort cloud and address exceptions to general rules.

Close Encounter Hypothesis

All proposed problems with the close encounter hypothesis are valid; none are exempt.

Protoplanetary Nebula Origins

The elements in the protoplanetary nebula originated from stars and supernovae that exploded before the solar system's formation.

Structure of the Protoplanetary Nebula

The flatness of the protoplanetary nebula resulted from particle collisions.

Temperature Influence in the Solar System

Temperature gradients caused the condensation of different materials at varying distances from the Sun.

Ingredients of the Solar Nebula

The solar nebula's ingredients ranked by abundance: metals, rocks, hydrogen compounds.

Density of Planets

Inner planets are denser because only dense materials condensed near the Sun.

Gas Condensation

Hydrogen and helium gas did not condense in the protoplanetary nebula.

Particle Accretion

Small particles in the solar nebula grew into planetesimals by colliding gently and sticking through electrostatic forces.

Formation of Jovian vs. Terrestrial Planets

Jovian planets formed differently as their planetesimals became large enough to capture hydrogen and helium.

Condensation Beyond the Frost Line

Hydrogen compounds, rocks, and metals condensed beyond the frost line.

Solar Rotation

The Sun's slow rotation is a result of angular momentum transfer to charged particles in the solar wind.

Conclusion of Planet Formation

Planet formation ceased when the solar wind expelled the remaining nebular gas.

Mass in the Asteroid Belt

Most mass from the asteroid belt either crashed into inner planets or was ejected from the solar system.

Jupiter's Retrograde Moons

Some of Jupiter's moons orbit in the opposite direction of its rotation due to capture as planetesimals.

Effects of Giant Impacts

Giant impacts explain features like the existence of Earth's large moon.

Unique Solar System Characteristics

The presence of a terrestrial planet with a large moon is a characteristic not necessarily found around other stars.

Radiometric Dating

Radiometric dating determines the time since a rock solidified.

Age of Meteorites

The oldest meteorites are approximately 4.55 billion years old.

Validity of Radiometric Dating

Validated through dates found on archaeological artifacts and consistency across multiple radiometric techniques.

Evidence for Solar System Formation

The solar system's formation theory is supported by planets’ consistent motion and rotation, conservation of angular momentum, observations of gas clouds, and disks around young stars.

Heating of the Solar Nebula

The primary physical law for the heating of the solar nebula during collapse is conservation of energy.

Increased Rotation Rate

Conservation of momentum explains the increased rotation rate as the solar nebula collapsed.

Density of Terrestrial vs. Outer Planets

The inner solar nebula was too hot for anything but dense metals and rocks to form, leading to the higher density of terrestrial planets.

Composition of the Solar Nebula

The solar nebula consisted of about 98% hydrogen and helium, with 2% heavier elements.

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Description

Test your knowledge on key concepts from Astronomy Chapter 4. These flashcards cover important theories regarding the formation of the solar system, including the categorization of planets and the characteristics of comets. Perfect for quick review before exams or as a study aid.