AstronomyLesson 1 of 1 in the course Other Worlds: An Introduction to the Solar System

Planetary Composition, Climate, and Geological Activity

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Planets and smaller solar-system bodies differ in their materials and internal structures. Comparing them helps explain how they formed and how their interiors developed.

Jupiter and Saturn are dominated by hydrogen and helium, with about 75% of their mass in hydrogen and 25% in helium. Their immense gravity compresses hydrogen deep inside until it becomes liquid, so calling them simply gas planets can be misleading. Uranus and Neptune also have cores of rock, metal, and ice, but they captured less hydrogen and helium and therefore have smaller atmospheres relative to their cores.

All flashcards

What does reduced chemistry mean for giant planets?
Hydrogen is abundant, and much of the oxygen is bound with hydrogen in compounds such as water.
What are terrestrial planets primarily made of?
They are made mainly of rock and metal; common silicate rocks contain silicon and oxygen, and iron is a major metal.
Differentiation
The separation of a body's interior into layers with different compositions and densities.
Tidal heating
Heat generated when gravitational interactions flex a moon, potentially sustaining subsurface liquid water or volcanism.
Why are some asteroids and comets called chemical fossils?
Many preserve relatively unchanged material from the solar system's formation, providing clues to its early ingredients.

Quiz questions

  1. Which elements make up most of Jupiter and Saturn by mass?Answer: Hydrogen and helium
  2. Why is Venus hotter at its surface than Mercury?Answer: Its thick carbon dioxide atmosphere slows the escape of heat.
  3. If a planet's distance from the Sun doubles, how does the sunlight received per unit area change?Answer: It falls to about one-quarter.
  4. Why do larger planets and moons generally cool more slowly than smaller bodies?Answer: They generally retain internal heat for longer.
  5. What primarily creates impact craters on planets and moons?Answer: Collisions with asteroids, comets, and other debris

Based on Astronomy 2e by Andrew Fraknoi, David Morrison, Sidney Wolff (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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