Comprehensive Science Review: Methodology, Earth Sciences, and Astronomy

Scientific Questions: Must be testable, empirical, clear, concise, and focused on only one aspect. Improper questions include double-barred queries (e.g., asking about two conditions like "gallstones and kidney diseases" simultaneously) or using vague terms like "feasible."
Hypotheses and Inferences:
- Hypothesis: An educated guess that must be testable, specified (concise), and aligned with the experimental design. Includes independent and dependent variables.
- Inference: A logical conclusion from data/observations. Must be unbiased and cyclic (leading to further research).
Hypothesis Types:
- Null Hypothesis ( $H_0$ ): Suggests no significant difference between conditions.
- Alternative Hypothesis ( $H_a$ or $H_1$ ): Suggests a significant difference. Can be one-tailed (specifies direction) or two-tailed (only suggests change).
Variables:
- Independent Variable: Changed by the researcher (e.g., Chemical $X$ ).
- Dependent Variable: The variable measured for change (e.g., etiolation of Plant Species $Y$ ).
- Controlled Variables: Maintained constant (e.g., water amount, sunlight).
- Extraneous Variables: Uncontrolled factors that may interfere with results (e.g., soil $pH$ ).

Data Categorization: Qualitative (focused on characteristics) vs. Quantitative (involving numbers and units).
Statistical Measures:
- Variance: Describes how much data points differ from the mean.
- Standard Deviation: Quantifies the amount of variation or dispersion.
Analysis Types:
- Descriptive: Summarizes trends (mean, median).
- Inferential: Draws conclusions using probability.
- Diagnostic: Examines causes of trends.
- Predictive: Forecasts future events.
- Prescriptive: Provides actionable recommendations.
Temperature Conversions:
- $Celsius$ to $Kelvin$ : $K = ^\text{o}C + 273.15$
- Water Freezing Point: $0^\text{o}C$ , $32^\text{o}F$ , $273.15\,K$
- Water Boiling Point: $100^\text{o}C$ , $212^\text{o}F$ , $373.15\,K$

Physical Properties: Shape is an oblate spheroid; age is $4.54$ billion years; radius is $6,371\,km$ ; equatorial circumference is $40,075\,km$ ; surface gravity is $9.81\,m/s^2$ .
The Goldilocks Zone: The habitable solar system region allowing liquid surface water.
Atmospheric Composition: $78\%$ Nitrogen ( $N_2$ ) and $21\%$ Oxygen ( $O_2$ ).
Atmospheric Layers:
- Troposphere: Surface to $8-15\,km$ ; coldest; contains all weather; densest.
- Stratosphere: Up to $50\,km$ ; temperature increases with altitude due to the ozone layer absorbing $UV$ radiation.
- Mesosphere: Up to $85\,km$ ; coldest layer ( $-90^\text{o}C$ ); where meteoroids burn.
- Thermosphere: Up to $600\,km$ ; stage for auroras; contains the Ionosphere for radio communication.
- Exosphere: Outermost layer; extends to $10,000\,km$ ; extremely thin air.

Compositional Layers: Crust (thinnest), Mantle ( $82\%$ volume, high silica/magnesium/iron), and Core ( $Ni$ and $Fe$ ; liquid outer/solid inner).
Mechanical Layers: Lithosphere (broken into tectonic plates), Asthenosphere (semi-fluid/ductile), and Mesosphere (rigid lower mantle).
Continental Drift Theory: Proposed by Alfred Wegener; suggests a single supercontinent (Pangaea).
Plate Boundaries:
- Convergent (Destructive): Plates collide. Includes Oceanic-Continental (trenches/volcanoes), Oceanic-Oceanic (Mariana Trench), and Continental-Continental (mountains).
- Divergent (Constructive): Plates move apart. Leads to seafloor spreading, Mid-Ocean Ridges (Mid-Atlantic Ridge), and Rift Valleys (East African Rift Valley).
- Transform: Plates slide past each other (seismic activity).

Earthquakes:
- Focus (Hypocenter): Origin point within Earth.
- Epicenter: Point directly above focus on the surface.
- Waves: $P$ -waves (fastest, travel through all states) and $S$ -waves (slower, only solids and gases).
- Measurement: Magnitude ( $M_w$ ) measures energy using seismographs; Intensity ( $MMI$ ) measures damage using observations.
Volcanoes:
- Shapes: Shield (low viscosity lava), Composite/Stratovolcano (explosive, logic layers), and Cinder Cone (short-lived, steep slopes).
- Lava Composition: Felsic (silica $>65\%$ ; viscous), Andesitic ( $52-63\%$ silica), Mafic ( $45-52\%$ silica; fluid), and Ultramafic ( $<45\%$ silica).
- Flow Characteristics: Pahoehoe (smooth/ropy), Aa (rough/jagged), Blocky (angular), and Pillow (underwater).

Rock Types:
- Igneous: Intrusive (Granite) or Extrusive (Basalt, Obsidian).
- Sedimentary: Clastic (Sandstone), Chemical (Limestone), and Organic (Coal).
- Metamorphic: Foliated (Schist, Gneiss) or Non-foliated (Marble from limestone, Quartzite from sandstone).
Soil Horizons: $O$ (Organic), $A$ (Topsoil), $B$ (Subsoil), $C$ (Parent Material), and $R$ (Bedrock).
Weathering vs. Erosion: Weathering breaks rock in place (Mechanical, Chemical, Biological); Erosion transports fragments (Water, Wind, Glacial, Gravity).
Hydrosphere: covers $71\%$ of Earth. Total volume is $1.386$ billion $km^3$ . $97\%$ is Saltwater; $3\%$ is Freshwater.

Planetary Classification: Terrestrial (Mercury to Mars), Gas Giants (Jupiter, Saturn), and Ice Giants (Uranus, Neptune).
Star Evolution: Nebula $\rightarrow$ Main Sequence (hydrogen fusion) $\rightarrow$ Giant/Supergiant $\rightarrow$ White Dwarf, Neutron Star, or Black Hole.
Galaxies: Spiral (Milky Way), Elliptical (older), and Irregular.
The Moon: Formed via the Giant Impact Hypothesis (collision with planet Theia). Gravity is $\frac{1}{6}$ of Earth's; distance is $384,400\,km$ .