Key Takeaways
- Earth's layers: crust, mantle, outer core (liquid), inner core (solid)
- Three rock types: igneous (cooled magma), sedimentary (compressed layers), metamorphic (heat/pressure)
- Water cycle: evaporation, condensation, precipitation, collection
- Rotation (24 hrs) = day/night; Revolution (365 days) + tilted axis = seasons
- Planet order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Last updated: January 2026
4.1 Earth and Space Science
Earth and Space Science covers about 33% of the Science subtest, including Earth's systems, weather, and the solar system.
Earth's Layers
| Layer | Characteristics |
|---|---|
| Crust | Thin outer layer (5-70 km), where we live |
| Mantle | Thick, hot rock, convection currents |
| Outer Core | Liquid iron and nickel |
| Inner Core | Solid iron and nickel (extreme pressure) |
Plate Tectonics
Types of plate boundaries:
| Boundary | Movement | Results |
|---|---|---|
| Convergent | Plates move toward each other | Mountains, volcanoes, trenches |
| Divergent | Plates move apart | Mid-ocean ridges, rift valleys |
| Transform | Plates slide past each other | Earthquakes (San Andreas Fault) |
The Rock Cycle
Three types of rocks:
| Type | Formation | Examples |
|---|---|---|
| Igneous | Cooled magma/lava | Granite, basite, obsidian |
| Sedimentary | Layers of sediment compressed | Sandstone, limestone, shale |
| Metamorphic | Changed by heat and pressure | Marble, slate, quartzite |
Weather vs. Climate
- Weather: Day-to-day atmospheric conditions
- Climate: Average weather conditions over a long time
The Water Cycle
| Stage | Process |
|---|---|
| Evaporation | Water changes from liquid to gas |
| Condensation | Water vapor cools and forms clouds |
| Precipitation | Water falls as rain, snow, sleet, hail |
| Collection | Water gathers in oceans, lakes, groundwater |
Earth in Space
Solar System:
- Sun: Center of our solar system (star)
- 8 planets (in order): Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
- Inner planets: Rocky (terrestrial)
- Outer planets: Gas giants
Earth's Motions:
| Motion | Period | Causes |
|---|---|---|
| Rotation | 24 hours | Day and night |
| Revolution | 365.25 days | Seasons (due to tilted axis) |
Moon Phases: New Moon → Waxing Crescent → First Quarter → Waxing Gibbous → Full Moon → Waning Gibbous → Third Quarter → Waning Crescent
Test Your Knowledge
What type of rock is formed when magma cools?
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Test Your Knowledge
What causes day and night on Earth?
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Test Your Knowledge
Which plate boundary causes earthquakes as plates slide past each other?
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