Astronomy Midterm Exam Review

Solar System

The Sun plus everything gravitationally bound to it, including 8 planets, dwarf planets, moons, asteroids, comets, and more.

Dwarf Planets

Smaller planetary bodies, including Pluto, Eris, Haumea, Makemake, and Ceres.

Asteroids

Rocky/metallic bodies mostly found in the asteroid belt, ranging in size from millimeters to hundreds of kilometers.

Comets

Icy celestial bodies that develop comae and tails when near the Sun, originating from the outer solar system.

Kuiper Belt

A disk-shaped region beyond Neptune, containing icy bodies and the source of short-period comets.

Oort Cloud

A hypothesized spherical region far beyond the Kuiper Belt, thought to be a reservoir of long-period comets.

Interplanetary matter

All solid and gaseous material that exists in the space between planets in the solar system. (basically everything that’s not a planet, moon, or large object in the interplanetary medium.)

Example:

• Astroids (rocky and bigger than meteriods

• Meteoroids (rocky)

• Icy Objects

• Comets (Icy with some rock and dust)

Terrestrial Planets

INNER Rocky, solid planets closer to the Sun with higher densities; includes Mercury, Venus, Earth, and Mars.

Jovian Planets

OUTER Large, low-density planets with thick atmospheres; includes Jupiter, Saturn, Uranus, and Neptune.

Asteroids vs Comets

Asteroids are rocky; comets are icy, and they behave differently when near the Sun.

Asteroid Belt

belt closest to the sun

objects found in Astroid Belt:

Asteroids, meteoroids, dwarf planets

Kuiper Belt vs Oort Cloud

Kuiper Belt is near the solar system's edge with frozen bodies; Oort Cloud is a distant spherical region.

Solar Nebula

The cloud of gas and dust that collapsed under gravity to form our solar system about 4.6 billion years ago. after spinning faster it flattened into a disk

Gravity Assist (slingshot)

Using a planet’s motion & gravity to change a spacecraft’s speed and direction relative to the Sun without using extra fuel.

Crust (Earth)

The outer layer of Earth, comprising continental and oceanic regions.

Mantle (Earth)

The layer beneath the crust that is solid but can flow slowly over time.

Outer Core

The liquid layer of Earth's core responsible for its magnetic field.

Inner Core

The solid, metallic center of Earth, primarily composed of iron and nickel.

Troposphere

The lowest layer of Earth’s atmosphere, where weather occurs and temperature decreases with altitude.

Greenhouse Effect

The trapping of heat in a planet's atmosphere by greenhouse gases, warming the surface.

P-waves

Primary seismic waves that compress and can travel through both solids and liquids.

S-waves

Secondary seismic waves that shear and can only travel through solids.

Shadow Zones

Areas where seismic waves do not arrive due to their path being blocked by Earth's core.

Divergent Boundaries

Where tectonic plates move apart, creating new crust.

Convergent Boundaries

Where tectonic plates collide, causing subduction or mountain building.

transform boundries

Where tectonic plates slide past one another, like the San Andreas Fault.

Auroras

Natural light displays in Earth's polar regions caused by solar wind interacting with the magnetosphere.

Tides

The rise and fall of sea levels caused by the gravitational pull of the Moon and Sun.

Impact Craters

Depressions on a planetary surface caused by collisions with asteroids or comets.

Giant-impact Hypothesis

Theory explaining the formation of Earth's Moon through a collision with a Mars-sized body called Theia

Lunar Maria

Dark, basaltic plains on the Moon formed by ancient volcanic activity.

Caloris Basin

Mercurys most prominent/visable land feature.

• A multi-ring crater/basin

• Ringed by mountain ranges

• Impact caused seismic waves inside mercury to create weird terrain on the other side

Mars' Tharsis Region

An immense volcanic plateau on Mars, home to the tallest volcano in the solar system (Olympus Mons)

Curiosity Rover

Mars rover that found evidence for ancient habitable conditions.

Seismic Evidence

Data from seismic waves used to infer the internal structure of celestial bodies.

Radiometric Dating

A method to determine the age of materials by measuring the decay of isotopes.

Mercury's Interior

Features a large core and a thin mantle, suggesting unique geological history.

Venus' Atmosphere

Characterized by a dense composition primarily of CO₂, creating extreme surface temperatures.

Past Water on Mars

Evidence found in the form of channels, deltas, and minerals indicating historical presence of water.

Polar Ice Caps on Mars

Layered deposits of water and CO₂ ice that change with seasonal cycles.

Life Potential on Mars

No confirmed life, but potential for habitability in the past or subsurface.

Seismic Wave Propagation

How P and S waves travel through Earth to reveal its layered structure.

Weird Terrain

• Unusual hilly texture on Mercury

• Created by seismic waves traveling inside mercury that resulted from the impact of the Caloris basin/crater

Scarps

(cliffs) formed when the planets crust cooled and shrank early in mercurys history and caused creases on the surface

Hollows

• look like small white textured spots on Mercurys surface

• land features not found anywhere else

• caused by sublimation (solid→ gas change)

Moon interior

Regolith

Thick layer of dust left behind from meteorite impacts

Formation of the Solar system

1. Nebula/solar nebula (cloud of gas and dust) forms

2. Nebular Contraction- gravity causesNebula/solar nebula (cloud of gas and dust) to collapse on itself

3. Disk Formation- flattens into spinning disk

4. Sun forms- most material moves to center to create the sun

5. Accretion- condensation causes gasses in the disk to cool and condese into solid particles (dust, rock, ice).

6. Planetesimals- are formed by acretion

7. Planets are made- more accretion happens by using planetesimals to create planets

phases of Venus

Retrograde Motion

Venusian atmosphere,

 polar vortex,

Volcanoes, lava domes

Ishtar Terra

Aphrodite Terra

Mars topography

Olympus Mons

Valles Marineris

, Hellas Basin

Viking, Pathfinder, Spirit,

Opportunity, Curiosity

,

Perseverance, Ingenuity,

Phoenix

, MRO

evidence of water on Mars?

• runoff channels,

• teardrop shaped islands

• deltas, gullies

• liquid impact crater ejecta

• Martian polar ice caps

• Swiss cheese terrain

Martian atmosphere, dust devils, frost

, dust storms

Magnetosphere