Science Exam PDF

## WHMIS Symbols The Workplace Hazardous Materials Information System (WHMIS) uses symbols to indicate different types of hazards associated with chemicals. These typically include: - Flammable (fire symbol) - Corrosive (material that can cause burns to skin/eyes) - Toxic (material that can cause...

## WHMIS Symbols The Workplace Hazardous Materials Information System (WHMIS) uses symbols to indicate different types of hazards associated with chemicals. These typically include: - Flammable (fire symbol) - Corrosive (material that can cause burns to skin/eyes) - Toxic (material that can cause serious health effects) - Compressed Gas (indicates gas under pressure) - Oxidizing (substances that can cause a fire or explosion) - Health Hazard (includes respiratory issues or other serious health effects) - Explosive (risk of explosion) - Environmental Hazard (may cause damage to the environment) ## Do's and Don'ts in the Science Lab ### Do's - Always wear appropriate personal protective equipment (PPE) like gloves and goggles. - Follow all instructions carefully. - Keep your workspace clean and tidy. - Label all containers correctly. - Dispose of chemicals and waste properly. ### Don'ts - Never eat or drink in the lab. - Do not put any substance by mouth. - Never work alone in the lab. - Avoid running or playing around. - Do not ignore safety instructions or warnings. ## Significant Figures and Rounding Significant figures (sig figs) are the digits in a number that contribute to its accuracy. When rounding: 1. Look at the digit to the right of your rounding cutoff. 2. If it's 5 or higher, round up the last significant figure. 3. If it's lower than 5, keep the last significant figure as is. ## Scientific Method The scientific method is a systematic process for conducting experiments and analyses: 1. Ask a Question - Identify a problem or question. 2. Do Background Research - Gather information. 3. Construct a Hypothesis - Formulate a testable prediction. 4. Test Your Hypothesis by Conducting an Experiment - Collect data through experiments. 5. Analyze Your Data and Draw a Conclusion- Interpret data to see if it supports the hypothesis. 6. Communicate Your Results - Share your findings with others. ## Graphing (Applicable to All Units) ### Identifying proper scales for a graph: Choose scales that make your data easy to read and interpret. This usually means evenly spaced intervals that cover the range of your data. ### Plotting Data: Accurately mark data points on your graph based on the collected data. Use good spacing to ensure clarity. ### Drawing a Line of Best Fit: This line represents the trend of your data. It doesn't need to pass through all points but should reflect the overall pattern. ### Determining the Slope of a Line of Best Fit: Slope = (change in y / change in x). It represents the rate of change in your data and can often help in understanding the relationship between variables. ## Unit 1: Chemistry: ### Chapter 4 #### 4.1 - Studying Matter - **Pure Substances:** These are materials with a consistent composition throughout. Example: distilled water, pure elements like gold or silver. - **Elements vs Compounds:** - **Elements:** Consist of only one type of atom. Example: Oxygen (O2). - **Compounds:** Consist of two or more elements chemically combined. Example: water (H2O). - **Mixtures:** A physical combination of two or more substances where each retains its individual properties. Example: sand in water. - **Homogeneous Mixtures (Solutions):** Have a uniform composition throughout. Example: saltwater. - **Heterogeneous Mixtures:** Do not have a uniform composition. Example: oil and water. - **Mechanical Mixtures:** Different parts can be seen with the naked eye. Example: a salad. - **Suspensions:** Particles are dispersed but can settle over time. Example: muddy water. - **Solutions:** Solute particles are dissolved completely in the solvent. Example: sugar dissolved in water. #### 4.2 - Physical Properties - **Qualitative vs Quantitative Physical Properties:** - **Qualitative:** Descriptions without measurements. Example: color, texture. - **Quantitative:** Involves measurements. Example: mass, volume, density. - **States of Matter:** The different forms in which matter can exist: solid, liquid, gas, and plasma. #### 4.2 - A Study of Density - **Density Calculations (D, M, V):** Density (D) is mass (M) per unit volume (V). D = M/V. - **Mass vs Volume Graph:** A graph where the slope (rise/run) represents the density of the substance. - **Slope of Mass vs Volume Graph:** The density of the substance. A steeper slope means a higher density. - **Density Lab:** An experiment where you measure the mass and volume of different objects to calculate their densities. #### 4.3 - Chemical Properties - **Reactivity with Other Substances:** Water, Oxygen, Acids, Other Pure Substances How a substance reacts with these can indicate its chemical properties. - **Combustibility:** Ability of a substance to burn. - **Stability:** How likely a substance is to remain unchanged under normal conditions. - **Toxicity:** How harmful a substance is to living organisms. - **Chemical vs. Physical Changes:** - **Chemical Changes:** Result in the formation of new substances. Example: rusting of iron. - **Physical Changes:** Do not produce new substances. Example: melting ice into water. ## Chapter 5 #### 5.1 - History of the Atom - **Ancient Greek Philosophers:** Early philosophers like Democritus and Leucippus proposed that matter is composed of indivisible particles called atoms (from Greek "atomos," meaning "indivisible"). - **John Dalton:** Developed the first modern atomic theory, which stated that elements consist of tiny particles called atoms, and that atoms of an element are identical. - **J.J. Thompson:** Discovered the electron using cathode ray tubes, leading to the "plum pudding" model of the atom. - **Ernest Rutherford:** Conducted the Gold Foil Experiment, discovering the nucleus and proposing that atoms have a small, dense, positively charged center surrounded by electrons. - **Nagaoka:** Proposed a Saturnian model of the atom with electrons revolving around a central nucleus. - **James Chadwick:** Discovered the neutron, further refining the atomic model. #### 5.1 - Specific Models and Discoveries - **Dalton's Model:** Proposed that atoms are indivisible and indestructible particles with unique weights and properties for each element. - **Thompson's Cathode Ray Tubes:** Experiments showed that atoms contain negatively charged particles (electrons). - **Rutherford's Gold Foil Experiment:** Revealed that atoms consist of a dense nucleus surrounded by a cloud of electrons. - **James Chadwick's Discovery of Neutrons:** Identified the presence of neutral particles in the nucleus, explaining the missing mass in atoms. #### 5.2 - Structure of the Atom - **Subatomic Particles:** Atoms consist of protons (positively charged), neutrons (neutral), and electrons (negatively charged). - **Representing Elements with Chemical Symbols:** Each element is represented by a one or two-letter symbol, e.g., H for Hydrogen, O for Oxygen. - **Determining Atomic Number, Number of Protons, Electrons, Mass Number, and Neutrons:** - **Atomic Number:** Number of protons in the nucleus of an atom. - **Number of Protons = Number of Electrons** in a neutral atom. - **Mass Number:** Sum of protons and neutrons in the nucleus. - **Number of Neutrons:** Mass number - atomic number. - **Isotopes:** Atoms of the same element that have different numbers of neutrons and therefore different mass numbers. #### 5.2 - Bohr-Rutherford Diagrams to Represent Atoms - **Bohr-Rutherford Diagrams:** Illustrate the arrangement of protons, neutrons, and electrons in an atom. Electrons are shown in specific energy levels or shells around the nucleus. #### 5.3 - The Periodic Table - **Types of Elements:** - **Metals:** Typically solid at room temperature, good conductors of heat and electricity. Example: Iron (Fe). - **Metalloids:** Have properties of both metals and non-metals. Example: Silicon (Si). - **Non-metals:** Poor conductors of heat and electricity, can be gases, liquids, or brittle solids. Example: Oxygen (O). #### 5.4 - Trends in the Periodic Table - **Reactivity:** Elements show varying reactivity, with metals typically becoming more reactive down a group, and non-metals showing opposite trends. - **Atomic Size:** Generally increases down a group and decreases across a period from left to right. ## 6.1, 6.2 - Properties of Ionic and Molecular Compounds - **Ionic Compounds:** - **Formation:** Formed from the transfer of electrons between a metal and a non-metal, resulting in the formation of positive and negative ions. - **Properties:** - Usually solid at room temperature. - High melting and boiling points. - Conduct electricity when dissolved in water (electrolytes). - **Example:** Sodium chloride (NaCl). - **Molecular Compounds:** - **Formation:** Formed from the sharing of electrons between two non-metals. - **Properties:** - Can be solids, liquids, or gases at room temperature. - Lower melting and boiling points compared to ionic compounds. - Do not conduct electricity in water. - **Example:** Water (H2O). ## 6.1, 6.2 - Naming Ionic and Molecular Compounds (Formulas and Names) - **Naming Ionic Compounds:** - **Cation (positive ion):** Named first, using the element's name. If it's a transition metal, include the charge in Roman numerals. - **Anion (negative ion):** Named second, using the element's root name + "ide". - **Example:** NaCl is sodium chloride. FeCl3 is iron(III) chloride. - **Naming Molecular Compounds:** - **Prefix** + **element name** for the first element (if there's more than one atom). - **Prefix** + **element root name** + "ide" for the second element. - **Prefixes:** mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), etc. - **Example:** CO2 is carbon dioxide. N2O5 is dinitrogen pentoxide. ## 6.3 - Bohr-Rutherford Diagrams for Molecular Compounds - **Bohr-Rutherford Diagrams:** - **Bohr Diagram:** Shows all electrons in specific energy levels or shells around the nucleus. - **Rutherford Diagram:** Showcases the nucleus with the number of protons and neutrons, and energy levels with dots representing electrons. - **For molecular compounds:** Depict the sharing of electrons between atoms via covalent bonds, with each atom satisfying the octet rule. - **Example:** For H2O (water), draw the oxygen atom sharing electrons with two hydrogen atoms to form covalent bonds. ## Unit 2: Ecology ### Sustainable Ecosystems ### Chapter 1 #### 1.1 - Parts of an Ecosystem and Sustainability - **Biotic Factors:** All living components of an ecosystem (plants, animals, bacteria). - **Abiotic Factors:** Non-living elements (water, air, minerals, temperature). - **Sustainability:** An ecosystem's ability to maintain ecological processes over time, ensuring a balance between consumption, reproduction, and natural resource renewal. #### Nutrient Cycles (Cycling of Matter) - **Hydrologic Cycle (Water):** Describes the movement of water through the atmosphere, on land, and through bodies of water. Includes evaporation, condensation, and precipitation. #### Water Cycle Step by Step 1. **Evaporation:** - **Process:** Water from oceans, lakes, rivers, and other bodies of water is transformed into water vapor by the heat of the sun. - **Result:** The water vapor rises into the atmosphere. 2. **Transpiration:** - **Process:** Plants absorb water through their roots and release water vapor into the air through small openings in their leaves called stomata. - **Result:** Adds moisture to the atmosphere, similar to evaporation. 3. **Condensation:** - **Process:** As water vapor rises and cools in the atmosphere, it turns back into liquid water droplets, forming clouds. - **Result:** Clouds are formed, which are masses of water droplets or ice crystals suspended in the atmosphere. 4. **Precipitation:** - **Process:** When water droplets in clouds combine and grow heavy enough, they fall to Earth due to gravity. - **Result:** Water returns to the surface in forms such as rain, snow, sleet, or hail. 5. **Seepage:** - **Process:** Water on the ground surface enters the soil and moves underground. - **Result:** Becomes part of the groundwater system, replenishing aquifers. 6. **Runoff:** - **Process:** Water flows over the land surface towards bodies of water like rivers, lakes, and oceans. This can also include melting snow and ice. - **Result:** Returns water to oceans and other bodies of water, continuing the cycle. 7. **Groundwater Flow:** - **Process:** Water moves slowly through the soil and rocks underground, eventually reaching bodies of water. - **Result:** Contributes to the replenishment of rivers, lakes, and oceans. #### Carbon Cycle: Involves the flow of carbon among the atmosphere, hydrosphere, lithosphere, and biosphere. Photosynthesis and respiration are key processes. #### Step-by-Step Carbon Cycle 1. **Photosynthesis:** - **Process:** Plants, algae, and some bacteria absorb carbon dioxide (CO2) from the atmosphere. - **Action:** These organisms use sunlight to convert CO2 and water into glucose (C6H12O6) and oxygen (O2) through photosynthesis. - **Result:** Carbon is stored in plants as organic molecules. This is the foundation of the food chain. 2. **Respiration:** - **Process:** All living organisms, including plants, animals, and microorganisms, break down glucose for energy. - **Action:** Glucose (C6H12O6) is converted back into CO2 and water, returning CO2 to the atmosphere. - **Result:** Carbon moves through the food chain and returns to the atmosphere as CO2 through respiration. 3. **Decomposition:** - **Process:** When plants, animals, and other organisms die, decomposers like bacteria and fungi break down their bodies. #### Nitrogen Cycle: The conversion of nitrogen between different chemical forms, essential for DNA and protein production. Includes nitrogen fixation, nitrification, and denitrification. #### Step-by-Step Nitrogen Cycle 1. **Nitrogen Fixation:** - **Process:** Converting atmospheric nitrogen (N2) into ammonia (NH3) or related compounds. - **Action:** This is primarily done by nitrogen-fixing bacteria found in soil or in the root nodules of leguminous plants and through industrial processes. - **Result:** Atmospheric nitrogen, which most organisms cannot use, is converted into a form usable by plants and other organisms. 2. **Ammonification (Decay):** - **Process:** Decomposition of organic nitrogen compounds (from dead plants and animals) into ammonium (NH4+). - **Action:** Decomposers like fungi and bacteria break down proteins and nucleic acids in dead organisms, releasing ammonium into the soil. - **Result:** Ammonium enriches the soil, making nitrogen available for other processes. 3. **Nitrification:** - **Process:** Conversion of ammonium into nitrites (NO2-) and then nitrates (NO3-) by nitrifying bacteria. - **Action:** This occurs in two steps: - Oxidation of Ammonium (NH4+) to Nitrite (NO2-): This step is performed by bacteria such as Nitrosomonas. - Oxidation of Nitrite (NO2-) to Nitrate (NO3-): This is carried out by Nitrobacter bacteria. - **Result:** Nitrates, which plants can readily absorb and use, accumulate in the soil. 4. **Assimilation:** - **Process:** Plants absorbing nitrates (NO3-) and ammonium (NH4+) from the soil. - **Action:** Plants incorporate these nitrates and ammonium into organic molecules like proteins and nucleic acids. - **Result:** Nitrogen becomes part of plant tissues, entering the food chain as animals consume plants. 5. **Denitrification:** - **Process:** Conversion of nitrates (NO3-) back to atmospheric nitrogen (N2) by denitrifying bacteria. - **Action:** These bacteria, including species like Pseudomonas and Clostridium, perform this process under anaerobic (low oxygen) conditions. - **Result:** Nitrogen is returned to the atmosphere, completing the nitrogen cycle. #### 1.2 - Energy Flow through Ecosystems - **The Leaf, Chlorophyll, Photosynthesis:** Chlorophyll in leaves absorbs sunlight to convert carbon dioxide and water into glucose and oxygen. - **Cellular Respiration:** Process in which cells convert glucose and oxygen into energy, carbon dioxide, and water. - **Trophic Levels and Trophic Efficiency:** Different levels in a food chain, from producers to top consumers. Energy transfer between levels is inefficient, often as low as 10%. #### 1.2 - Biomagnification and Bioaccumulation - **Bioaccumulation:** The accumulation of substances, like pesticides, in an organism over time. - **Biomagnification:** The increase in concentration of substances in the food chain, affecting top predators the most. #### 1.3 - Photosynthesis and Carbon Dioxide - **Photosynthesis - Extracting Energy from Biomass:** The process plants use to convert CO2 and sunlight into glucose, which can be stored and used as an energy source. - **Greenhouse Gases:** - **The Greenhouse Effect:** Natural process where certain gases trap heat in the atmosphere, maintaining Earth's temperature. - **The Enhanced Greenhouse Effect:** Human activities increase concentrations of greenhouse gases, leading to global warming. ### Chapter 2 #### 2.1 - Populations - **Exponential Growth:** Population increases under ideal conditions, producing a J-shaped growth curve. - **Limiting Factors:** Factors that control the growth of a population (food, space, disease). - **Carrying Capacity:** Maximum population size that an environment can support sustainably. - **Effects of Human Activities:** Human actions can alter population sizes and carrying capacities through deforestation, pollution, and urbanization. #### 2.2 - Interactions Among Species - **Ecological Niche:** The role and position a species has in its environment. - **Symbiosis:** Close and long-term interaction between species; includes mutualism, commensalism, and parasitism. - **Mutualism:** When they both benefit - **Commensalism:** One benefit and the other isn't harmed - **Parasitism:** When one benefits and the other is harmed - **Predator-Prey Relationships:** One organism hunts and consumes another. - **Top-Down and Bottom-Up Regulation:** Top-down (predators control prey populations), bottom-up (availability of resources controls populations). #### 2.3 - Human Niches and Population - **Sustainable Use of Resources:** Using resources in ways that do not deplete them for future generations. - **Carrying Capacity of Human Population:** The maximum population size that humans can sustainably maintain. - **Ecological Footprint:** Measure of human demand on Earth's ecosystems. #### 2.4 - Ecosystem Services - **Influence of Forests:** Forests provide habitat, regulate climate, and cycle nutrients. - **Desertification:** The process by which fertile land becomes desert. - **Watersheds:** Areas of land where water drains to a common point, essential in the water cycle. - **Insects:** Vital for pollination, and as part of the food chain. - **Pollination:** Transfer of pollen critical for plant reproduction. - **Decomposition:** Breakdown of organic matter, returning nutrients to the soil. - **Migratory Birds:** Seasonal movement of birds, important for various ecological processes. Birds' new ecosystem is affected as they use the resources to sustain themselves. ### Chapter 3 #### 3.1 - Measuring Biodiversity - **What is Biodiversity?** The variety of life in a particular habitat or ecosystem. - **Importance of Biodiversity:** Maintains ecosystem function, resilience, and provides resources for survival. - **Biodiversity Hotspots:** Areas with a high number of species endemic to that region and under threat. #### 3.2 - Communities - **Dominant Species:** Species with significant influence over the structure and function of a community. - **Keystone Species:** Species that play a crucial role in maintaining the structure of an ecosystem. - **Captive Breeding:** Breeding programs aimed at increasing population numbers of endangered species. - **Ecosystem Engineer:** Species that significantly modify their habitat. - **Ecological Succession:** The process of change in species structure of an ecological community over time. #### 3.3 - Threats to Biodiversity - **Habitat Loss:** Destruction or alteration of habitats. - **Deforestation:** Large-scale removal of forests. - **Draining Wetlands:** Conversion of wetlands for agriculture or urban use. - **Alien and Invasive Species:** Non-native species that disrupt local ecosystems. - **Overexploitation:** Excessive use of resources leading to depletion. - **Disrupting Connectivity:** Fragmentation of habitats affecting species movement and genetic exchange. #### 3.4 - Extinction - **How Does it Occur?** Natural events or human activities eliminate species. - **Patterns of Natural Extinction:** Background extinction due to natural changes and mass extinctions due to catastrophic events. - **Carbon sinks hold and store carbon.** **Examples** - Plants and animals - Ocean water - Oil deposits - Soil - Polar ice - Atmospheres - **How does carbon get into the atmosphere?** - Respiration - Burning fossil fuels - Decomposition - Melting ice - **Eutrophication:** A process where water bodies like lakes, rivers, and oceans become overly enriched with nutrients, leading to an increase in plant and algae growth. This often results in detrimental effects on the aquatic environment. - **Cellular respiration:** C6 H12O6 + O2 + H2O + ATP ## Unit 3: Electricity ### Chapter 10 - Static Electricity #### 10.1 - Law of Electric Charges and Electrostatic Series - **Law of Electric Charges:** Opposite charges attract and like charges repel each other. - **Electrostatic Series:** A list that ranks materials according to their tendency to gain or lose electrons. Materials higher on the list gain electrons and become negatively charged, while those lower lose electrons and become positively charged. #### 10.1-Bohr-Rutherford Model of the Atom - **Bohr-Rutherford Model:** Depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus. Electrons are arranged in energy levels or shells.; #### 10.1 - Net Positive Charge, Net Negative Charge, Net Neutral Charge - **Net Positive Charge:** Occurs when an atom or material loses electrons, resulting in more protons than electrons. - **Net Negative Charge:** Occurs when an atom or material gains electrons, resulting in more electrons than protons. - **Net Neutral Charge:** When the number of protons equals the number of electrons, the overall charge is neutral. #### 10.1 Charging by Friction - **Charging by Friction:** When two different materials are rubbed together, electrons are transferred from one material to the other, causing one to become positively charged and the other negatively charged. #### 10.2 - Laws of Electric Charges - **Laws:** These laws dictate how charged objects interact with each other. Oppositely charged objects attract; like charged objects repel. #### 10.2 - Charging by Contact - **Charging by Contact:** Transferring charge by touching or rubbing. When a charged object touches a neutral object, the neutral object obtains the same charge. #### 10.2 - Charging by Conduction - **Charging by Conduction:** A method where a charged object touches another object, and electrons flow between them until equilibrium is reached. #### 10.2 - Electroscopes - **Electroscopes:** Instruments used to detect electric charge. They show the presence of charge and its relative magnitude. #### 10.2 - Grounding - **Grounding:** The process of transferring excess charge to the Earth, which can absorb an infinite amount of charge. #### 10.3 - Static Discharge, Lightning, Lightning Rods, Spray Painting, Photocopying - **Static Discharge:** Sudden flow of electricity between two charged objects due to build-up of static electricity. - **Lightning:** A giant electric discharge between the atmosphere and the ground, caused by the build-up of charge in storm clouds. - **Lightning Rods:** Metal rods placed on buildings to protect them from lightning by providing a direct path to the ground. - **Spray Painting:** Uses static electricity to ensure even coating of paint. The object to be painted is charged, and oppositely charged paint particles are attracted to it. - **Photocopying:** Uses static electricity to transfer toner particles (ink) onto paper to form an image. ### Chapter 11 - Current Electricity #### 11.1 - How Batteries Work (Types of Cells) - **Batteries:** Devices that store chemical energy and convert it to electrical energy when needed. - **Types of Cells:** - **Primary Cells:** Disposable; cannot be recharged. Example: Alkaline battery. - **Secondary Cells:** Rechargeable; can be used multiple times. Example: Lithium-ion battery. #### 11.2 - Conductors vs Insulators - **Conductors:** Materials that allow electrons to flow freely. Example: copper wire. - **Insulators:** Materials that do not allow electrons to flow freely. Example: rubber. #### 11.2- Movement of Electrons - **Movement:** Electrons flow from the negative terminal to the positive terminal in a circuit. - **Calculations (Q, I, t):** - **Charge (Q):** Measured in coulombs (C). - **Current (I):** The flow of electric charge, measured in amperes (A). - **Time (t):** Duration of current flow, measured in seconds (s). #### 11.2 - Circuit Symbols and How to Draw Circuit Diagrams - **Circuit Symbols:** Standard symbols used to represent different components in a circuit (battery, resistor, switch). - **Circuit Diagrams:** Schematic representations of electrical circuits using symbols. #### 11.2 - Potential Difference and Energy - **Potential Difference (Voltage):** The work done per unit charge, measured in volts (V). - **Energy (E):** The capacity to do work, measured in joules (J). - **Calculations (V, E, Q):** $V = \frac{E}{Q}$ #### 11.3 - Measuring Current and Voltage in Simple Circuits - **Using Ammeters and Voltmeters:** - **Ammeter:** Measures current; connected in series. - **Voltmeter:** Measures voltage; connected in parallel. #### +11.4- Electrical Resistance - **Resistance (R):** Opposition to the flow of current, measured in ohms (Ω). - **Ohm's Law:** $V = IR$ - **Factors Affecting Resistance:** Material, length, cross-sectional area, temperature. - **Ohmic vs Non Ohmic Resistors:** Ohmic resistors follow Ohm's Law; non ohmic resistors do not. #### 11.5 Series and Parallel Circuits - **Series Circuits:** Components connected end-to-end; same current flows through each component. - **Parallel Circuits:** Components connected across the same two points; same voltage across each #### Voltaic Cell A source of energy that generates electrical currents by chemical reactions involving two different metals separated by a solution that is a conductor. ## Unit 4: Astronomy ### Chapter 7 #### 7.1 - Significance and Uses of the Night Sky The night sky has been significant for navigation, timekeeping, and cultural stories throughout human history. Stars, constellations, and celestial events have guided explorers and inspired myths and legends. #### 7.2 - The Constellations (Movement) - **Constellations:** Patterns of stars in the night sky, often associated with mythological figures, animals, or objects. - **Movement:** As Earth rotates and orbits the sun, constellations appear to move across the sky. Different constellations are visible at different times of the year. #### 7.3 - Movements of the Earth and Moon - **Seasons:** Result from Earth's axial tilt as it orbits the sun, causing variations in sunlight received at dif/ferent latitudes. - **Eclipses:** - **Solar Eclipse:** The moon moves between Earth and the sun, blocking sunlight. - **Lunar Eclipse:** Earth moves between the sun and the moon, causing Earth's shadow to fall on the moon. #### 7.4 - The Solar System - **Contents:** - **Inner Planets:** Mercury, Venus, Earth, and Mars. Rocky surfaces, relatively small. - **Outer Planets:** Jupiter, Saturn, Uranus, and Neptune. Gas giants (Jupiter and Saturn) and ice giants (Uranus and Neptune). - **Comets:** Icy bodies that release gas and dust, forming a glowing head and tail as they approach the sun. - **Asteroids:** Rocky objects orbiting the sun, mostly found in the asteroid belt between Mars and Jupiter. - **Meteors:** Small rocky or metallic bodies from space that enter Earth's atmosphere and burn up, creating a streak of light. #### 7.4 - Distances - **AU (Astronomical Unit):** The average distance between Earth and the sun, about 149.6 million kilometers. - **Light Year:** The distance light travels in one year, about 9.46 trillion kilometers. #### 7.5 - Other Objects in the Solar System - **Trans-Neptunian Objects:** Objects that orbit the sun beyond Neptune, including dwarf planets like Pluto. - **Kuiper Belt:** A region of the solar system beyond Neptune's orbit, populated with many small icy bodies, including comets. - **Oort Cloud:** A hypothetical large spherical shell surrounding the solar system, believed to contain many icy bodies and potential comets. #### Ancient Civilizations - **Mesopotamians** - **Astronomy and Astrology:** The Mesopotamians were among the first to systematically observe and record celestial events. They used a sexagesimal (base 60) numeral system to track movements of celestial bodies. This impact is still seen today in our divisions of time (e.g., 60 minutes in an hour). - **Calendars and Agriculture:** They developed lunar calendars based on the cycles of the moon, which helped regulate agricultural activities. The heliacal rising and setting of stars were used to predict seasonal changes essential for farming. - **Egyptians** - **Agriculture and Flooding of the Nile:** The Egyptians observed the heliacal rising of Sirius, which heralded the annual flooding of the Nile, marking the start of the agricultural calendar. This event was crucial for farmers to plan planting and harvesting seasons. - **Religious Beliefs:** The sun god Ra and other deities like Osiris and Nut were deeply connected to celestial bodies. Temples and pyramids were meticulously aligned with stars and constellations to channel divine energy and ensure cosmic harmony. - **Timekeeping and Calendars:** Egyptians utilized a 365-day civil calendar based on celestial observations, such as the heliacal rising of stars, to synchronize agricultural and religious events. - **Greeks** - **Mythology and Constellations:** Greek mythology is rich with stories linked to constellations. For example, Orion was seen as a hunter placed among the stars by Zeus. Such stories reflected their cultural values and beliefs. - **Philosophical and Scientific Approaches:** Greek philosophers like Thales, Anaximander, and Pythagoras made significant contributions to understanding the cosmos. They proposed naturalistic explanations for celestial phenomena, moving away from myths. - **Navigation and Calendars:** Greeks used stars for navigation, especially for sea voyages, and developed calendars to guide agricultural activities. Their understanding of planetary movements and geometry greatly influenced later astronomical studies. - **Sailors** - **Used the North Star to navigate through the sea.** #### Dependency on the night sky - **Architecture and Design** - **Ancient Temples and Pyramids:** Structures like the Egyptian pyramids and Stonehenge were aligned with celestial bodies. The Great Pyramid of Giza aligns with the stars in Orion's belt, reflecting their significance in Egyptian mythology. - **Observatories:** Ancient observatories, such as Chichen Itza in Mexico, were designed to observe celestial events like equinoxes and solstices. The Mayan El Caracol is another example, which was used to track the paths of Venus and other celestial objects. - **Relationships to Mythology** - **Constellations and Gods:** Many constellations are named after mythological figures. The Greeks, for example, named constellations such as Orion, which tells the story of a Greek hunter. - **Cultural Stories:** Across various cultures, the night sky plays a key role in mythologies, reflecting their views on creation, gods, and the cosmos. The Chinese mythological "Four Symbols" represent the four quadrants of the sky, each associated with a direction and season. - **Calendars** - **Lunar Calendars:** Early civilizations, like the Mesopotamians and Egyptians, developed lunar calendars based on the moon's phases, guiding agricultural and religious practices. - **Solar Calendars:** The Gregorian calendar we use today is based on the Earth's orbit around the sun, ensuring it aligns with seasons. Ancient civilizations like the Romans and Egyptians had solar calendars aligning important festivals and agricultural activities with solar events. - **Clocks** - **Sundials and Star Clocks:** Ancient clocks, such as sundials and star clocks, relied on the position of the sun and stars. Sundials, for instance, indicated time based on the shadow cast by the sun during the day. - **Shape of the Earth** - **Observations of Celestial Bodies:** Early Greek astronomers like Eratosthenes used the sun's angles at different latitudes to determine Earth's roundness. Observations of lunar eclipses showed Earth's shadow as round, supporting the spherical Earth hypothesis. - **Sailing and Stars:** Mariners noted the change in visible stars as they traveled north or south, further confirming that Earth is a sphere. - **Navigation** - **Stars and Constellations:** Navigators used stars to guide their journeys. The North Star (Polaris) is a famous example, remaining nearly stationary in the sky, helping sailors determine their latitude. - **Predicting Seasons** - **Equinoxes and Solstices:** Ancient civilizations observed the sun's position at times of equinoxes and solstices to predict seasonal changes, critical for agriculture. Stonehenge, for example, aligns with the sunset of the winter solstice. - **Seasonal Constellations:** Certain stars and constellations are only visible during specific seasons. Ancient farmers relied on these patterns to determine planting and harvesting times. #### Brightness of a Star - **Features of the sun** - Sun spots - Solar flares - Solar wind - **Factors affecting the brightness of a star** - Temp - Size - Distance - **The Great Red Spot on Jupiter** - A giant anti-cyclonic storm that had lasted at least 400 years in the hydrogen and helium clouds of Jupiter's atmosphere. - Jupiter rotates around its axis almost 2.5 times in one Earth day - Jupiter is 318 times the mass of Earth - Three Earths could fit in the storm - Wind over 600 km per hour - **Low mass star** - Nebula - Protostar - Main sequence - Red dwarf - White dwarf - Black dwarf - **Medium mass star** - Nebula - Protostar - Main sequence - Collapse - Red giant - Collapse - White dwarf - Black dwarf - **High mass star** - Nebula - Protostar - Main sequence - Red supergiant - Collapse - Iron core - Supernova - Black hole / Neutron star ==End of OCR==