Earth Science - Quick Review

Earth Science: Definition and Scope

  • Earth Science (also Geoscience) = study of Earth and the universe around it.
  • Studies natural phenomena since Earth’s formation ≈ 4.5×109 years ago4.5 \times 10^9\ \text{years ago}.
  • Also considered an environmental science focused on processes affecting our planet.

Why Study Earth?

  • Understand how our planet works.
  • Prepare for natural disasters.
  • Use natural resources wisely.
  • Address climate change and environmental issues.
  • Improve human life and society.

What is Earth Science?

  • Branches together explain Earth and its environment; integrates multiple scientific fields.
  • Also called Geoscience.

Five Branches of Earth Science

  1. Geology
  2. Oceanography
  3. Meteorology
  4. Astronomy
  5. Paleontology

Branch Highlights

  • Geology: study of Earth's surface; composition, structure, properties, history; processes that shape Earth.
  • Oceanography: study of oceans—physics, chemistry, biology, and geology.
  • Meteorology: study of weather and climate.
  • Astronomy: study of planets, stars, and other objects in the universe.
  • Paleontology: study of fossils and remains.

Paleontology in Action

  • Fossil examples: Argentinosaurus (largest dinosaur fossil; ~4.9×107 years4.9\times 10^7\text{ years} old) and other fossils like cockroach fossils.

Impact Hypothesis: Extinction of the Dinosaurs (Paleontology, Geology, Astronomy, Meteorology)

  • No dinosaur fossils exist in rock layers younger than ~6.5×107 years6.5\times 10^7\text{ years} ago.
  • Large impact crater in the Yucatán ~6.5×107 years6.5\times 10^7\text{ years} old.
  • Iridium layer worldwide in rocks around ~6.5×107 years6.5\times 10^7\text{ years} old (iridium is rare on Earth, common in meteoroids).
  • Climate models predict large impacts would alter Earth’s climate and affect life on Earth.

The Scientific Method (Lesson 02)

  • A systematic process for obtaining knowledge; used to determine what is scientific vs non-scientific.
  • Steps (in order):
    • Observe: make observations.
    • Question: ask a question/identify a problem.
    • Research: search for existing answers/solutions.
    • Hypothesize: formulate a hypothesis.
    • Experiment: design and perform an experiment.
    • Test Hypothesis: accept or reject the hypothesis.
    • Draw Conclusions: make conclusions based on the hypothesis.
    • Report: share your results.
  • This cycle helps organize knowledge acquisition.

Experimental Design (4 Components)

  1. Independent variable — the variable that is deliberately changed/manipulated. Also called the manipulated variable.
  2. Dependent variable — the variable that responds to changes in the independent variable. Also called the responding variable.
  3. Constant — a factor kept the same throughout the experiment.
  4. Control — baseline for comparison; remains the same.

Scientific Facts, Laws, Theories

  • Fact: an observed true statement.
  • Law: describes a pattern, often with math; does not explain why.
  • Theory: a verified explanation of a complex idea or natural phenomena; supported by extensive evidence.
  • Both laws and theories are supported by evidence from many observations and experiments.

Examples: Fact, Law, Theory (quick recall)

  • The Sun is the center of the solar system. — FACT\text{FACT}
  • Energy cannot be created or destroyed, only transformed. — LAW\text{LAW}
  • The Earth rotates on its axis every 24 hours. — FACT\text{FACT}
  • Species evolve over long periods via natural selection. — THEORY\text{THEORY}
  • For every action, there is an equal and opposite reaction. — LAW\text{LAW}

Measurement and Data (Lesson 03)

  • Data types:
    • Quantitative: numbers, amounts, measurements.
    • Qualitative: descriptions, qualities, non-numeric.
  • Measurements require units to have meaning.
  • Two systems:
    • English System (inch, foot, yard, ounce, pound, gallon, etc.).
    • System International (SI): base units standardized globally (meter, kilogram, liter, second, etc.).

The English vs SI Units (summary)

  • Length: English = feet, inches; SI = meter.
  • Mass: English = ounce, pound; SI = gram.
  • Time: English = second, minute, hour; SI = second.
  • Volume: English = teaspoon, cup, pint, quart, gallon; SI = liter.
  • Amount of substance: SI uses mole (mol); not common in English system.
  • Temperature: English uses Fahrenheit; SI uses Kelvin (K) and Celsius (°C).

Temperature Conversions (Formulas)

  • extoC=59(extoF−32)^ ext{o}C = \dfrac{5}{9} (^ ext{o}F - 32)
  • extoF=95(extoC)+32^ ext{o}F = \dfrac{9}{5} (^ ext{o}C) + 32
  • K=extoC+273.15K = ^ ext{o}C + 273.15
  • extoC=K−273.15^ ext{o}C = K - 273.15
  • K=59(extoF−32)+273.15K = \dfrac{5}{9} (^ ext{o}F - 32) + 273.15
  • extoF=95(K−273.15)+32^ ext{o}F = \dfrac{9}{5} (K - 273.15) + 32

SI Prefixes (Mnemonic)

  • Prefix sequence: Kilo-, Hecto-, Deca-, (base unit), Deci-, Centi-, Milli-
  • Powers of ten:
    • Kilo=103\text{Kilo} = 10^3
    • Hecto=102\text{Hecto} = 10^2
    • Deca=101\text{Deca} = 10^1
    • Base unit\text{Base unit}
    • Deci=10−1\text{Deci} = 10^{-1}
    • Centi=10−2\text{Centi} = 10^{-2}
    • Milli=10−3\text{Milli} = 10^{-3}
  • Memory aid: “King Henry Died By Drinking Chocolate Milk.”

Quick Recall: True/False Concepts (Key Points)

  • Scientific knowledge is built through systematic procedures (the scientific method).
  • Independent variable is what you change; dependent variable is what you measure.
  • A scientific theory is a well-supported explanation, whereas a law describes patterns; both are evidence-based.
  • SI units and metric prefixes enable global consistency in measurements.

Practical Quick Checks

  • If you see a statement about why something happens (e.g., gravity), think in terms of a theory rather than a law.
  • If you see a numerical relationship with units, express it in scientific notation when appropriate (e.g., 4.5×109 years4.5 \times 10^9\text{ years}).
  • For any data collection, remember to distinguish between numbers (quantitative) and descriptions (qualitative).