Astro 1010: Exam 3 Study Guide

Flashcards for vocabulary review.

Major objects in the solar system

One star, 8 planets, 5 dwarf planets (minimum), 200+ moons, millions of asteroids (estimated), trillions of comets (estimated).

Inner solar system

Mercury, Venus, Earth, Mars, and the asteroid belt; Smaller, rocky or metallic objects; Inner planets orbit the sun relatively close to each other.

Outer solar system

Jupiter, Saturn, Uranus, Neptune, the Kuiper belt, and the Oort cloud; Larger, icy or gaseous objects; Outer planets orbit the sun increasingly far apart.

Retrograde motion

Objects that orbit 'the wrong way'.

Triton

The largest moon of Neptune and an example of a retrograde moon

Catastrophic encounter hypothesis

States that material was ripped loose from the sun by a close encounter with another star, eventually forming the planets.

Falsified Catastrophic encounter hypothesis

Predicts very few planets in random, chaotic orbits around other stars, neither of which is true.

Collapsing nebular theory of planet formation

The solar system began as a gas cloud that imploded.

Conservation of angular momentum

Will flatten the nebula into an accretion disk.

Frost line

Hydrogen-based compounds like water (H2O) could only freeze into solids at a minimum distance from the sun.

Planetesimal

The early 'seeds' that grew through collisions with other objects into the planets.

Earth’s moon

Formed through the collision between Earth and a Mars-sized planetesimal.

Radiometric dating of asteroids

Confirms the solar system is about 4.5 billion years old.

Inner planets in order of increasing distance from the sun

Mercury, Venus, Earth, and Mars.

Inner planets and Earth’s moon in order of increasing size

Earth’s moon, Mercury, Mars, Venus, and Earth.

Planetary interiors

Metallic core (densest materials), rocky mantle (mostly middle-density silicate rock), rocky crust (mostly lower density rocks).

Lithosphere

Upper-most layers of a planet, composed of solid rock; includes all of the crust and the upper mantle.

Earth

Mostly nitrogen and oxygen atmosphere

Venus and Mars

Mostly carbon dioxide atmosphere

Mercury and Earth’s moon

No significant atmosphere

Greenhouse effect

Gases such as water vapor and carbon dioxide slow the loss of heat from a planet’s surface, raising the average temperature.

Caloris basin

Very large impact crater on Mercury; the impact event caused earthquakes and warped terrain all the way on the opposite side of the planet.

Maria

Dark regions on the moon’s surface; large volcanic plains that fill in massive craters and low-elevation areas; darker than surrounding rock due to the higher concentrations of iron.

Phobos and Deimos

Two small moons of Mars that are captured asteroids.

Jupiter

Most massive of the planets, arguably approaches the mass of the smallest stars.