study-notes

Science 9

They keep saying that the “jump” between grade 8 and 9 is larger than the one between grade 7 and 8; let’s see if it’s true.

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Workplace Hazardous Materials Information System

• In Canada, we have WHMIS to indicate the dangers associated with everything through the use of relatively simple symbols. There used to be an older version, but in 2015 the Government updated it to incorporate the Globally Harmonized System of Classification and Labelling of Chemicals (acronyms just almost as big as your mom).
  • A flame represents something flammable.
  • A flame on a circle represents an oxidizer.
  • An exploding bomb represents an explosive.
  • A gas cylinder represents gas under pressure.
  • A skull with crossbones represents acute toxicity.
  • A vial pouring on a surface and hand represents corrosion.
  • A human with streaks across the upper body represents a serious health hazard.
  • An exclamation mark represents irritation or a health hazard.
  • A fish in its environment represents aquatic toxicity.
  • A biohazardous symbol represents… biohazardous infections.

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Biodiversity

• Biological diversity refers to the number and variety of species and ecosystems on the Earth and the ecological processes that they’re a part of.
  • The Pacific Yew was thought to be a “trash” tree (only good for burning), until it was discovered that a drug could be made from it to fight cancer (Taxol).
  • The main components of biodiversity include:
    • Ecosystem diversity is the variation and diversity in the amount of different species in an ecosystem.
    • Species diversity occurs within individual organisms of the same species.
    • Genetic diversity occurs within organisms at a cellular level; it describes the variety of genetic material in all living things.
• Animals of the same species need to have similar genetic and physical characteristics and be able to reproduce, creating fertile offspring. (all humans are part of the same species)
  • The process of different types of organisms evolving from another species into their own species to adapt to their environment is called speciation. (cats evolve into different species of cats)
• Individuals form populations, which form communities, which form ecosystems, which form biomes, which form biospheres.
• Variations exist within the same species as well as between different species; they allow for ecosystems to remain healthy or to recover faster and are measured with the Diversity Index. There are two types of variations:
  • Continuous variations have a variety of different possibilities for the same trait. (height, weight, hair color, wingspan)
  • Discrete variations fall into specific categories. There is little to no “range”. (detached earlobes, tongue curling, blood type)
• Adaptations are traits that increase organisms’ chances of survival in particular environments. There are two types of adaptations:
  • Structural adaptations have to do with the physical aspects of an organism.
  • Behavioral adaptations have to do with the actions of an organism.
• A niche is the role an organism has within a particular ecosystem. It includes things like what it eats, what eats it, its habitat, nesting site, range, habits, and effect on populations and environment.
  • Animals living in extreme ecosystems, like in the very northern or southern parts of the world, have broad niches and are called generalists to accommodate to the extreme changes there.
  • Animals living in less extreme ecosystems, like near the equator, have narrow niches and are called specialists to accommodate to the stability.
• Species are linked by what each species depend on to survive. (bats depend on bugs to eat during the night, bugs depend on marshy areas like swamps to reproduce)
• When basic, needed resources (food, water, sunlight, habitat) aren’t plentiful, different species compete for the resource, and it’s often not fair, as different species have different variations that can provide a benefit (adaptations).
  • Some animals, like the warbler, practice resource partitioning on the same thing (like a tree) by only accessing resources from different, specific parts of it.
• When two creatures live in direct contact, with at least one benefiting, it’s called symbiosis.
  • When one organism benefits while the other is unaffected, it’s called commensalism. (the cattle egret follows cattle and eats the insects that are stirred up as the cattle feed)
  • Mutualism is when both organisms benefit. (the Egyption Plover eats parasites that attack crocodiles)
  • An organism hurting another for its benefit is parasitism. (tape worms live in the stomachs of mammals and can grow very long and old)
• Interspecies competition happens when two or more species need the same resource. This type of relationship helps to limit the size of the populations of the competing species.
• In asexual reproduction, only one parent is needed to reproduce.
  • Binary fission involves the duplication of a cell to create two. The genetic material in the original nucleus is duplicated. Only single-celled organisms reproduce in this way.
    • The newly created cell is called a daughter cell.
  • Some fungi like mushrooms can produce spores (little escape pods) that have all the genetic material needed to form another life form.
  • In vegetative growth, the meristem cells (at the edge of a growing plant that reproduces cells rapidly) can repair if damaged or grow into another plant upon falling off into fertile soil.
  • Budding is a form of asexual reproduction whereby daughter cells grow off of the parent cells then break off once mature enough.
  • In asexual reproduction, cell division leads to identical daughter cells. The new cell is genetically the same as the original. This means that organisms can’t adapt to their environment.
• In sexual reproduction, two parents are needed and each parent provides half of the required genetic material.
  • In bacterial conjugation, a connection is made between two bacterium and genetic material is transferred, but this isn’t reproduction because the numbers aren’t increased (this is a precursor to reproduction specifically for diversity).
  • Zoospores are spores that move using tail-like flagella.
  • Zygospores are spores that come from two parents. Once the zygospore finds an appropriate place, it will grow. (fungus, mold)
  • Some plants reproduce sexually:
    • Angiosperm plants produce flowers. The stamen is the male part, and the stigma is the female part. Pollen from the male part needs to make its way to the stigma, and many flowers require that the pollen comes from a different flower (cross-pollination).
    • Gymnosperm plants don’t produce flowers but produce cones called conifers. Pollen from the male cone is transferred, usually by the wind, to the female cone which eventually drops seeds.
  • Animals combine their gametes (sperm and eggs) outside or inside the body, depending on the species.
    • When a sex cell (gamete) is created, it contains half of the genetic code of the parent cell. Two parent cells combine to give the correct amount of genetic information.
    • A zygote is formed when two gametes meet (when an egg is fertilized).
    • An embryo is in the stage of development where structures are being formed, after a zygote’s cleavage (cell division).
• Offspring inherit heritable traits/characteristics from both of their parents, but not all of them are apparent.
  • Dominant traits (represented with D) will show up when at least one of the parents carry them. (black hair, brown eyes)
  • Recessive traits (represented with r) will show up when both parents carry them. (blonde hair, blue eyes)
  • Some traits are entirely dependent on the environment; they’re called nurture traits, rather than nature traits.
• Genetic information can be changed by factors in the environment to: mutations can cause changes in the structures of organisms, due to mutagens. (X-rays, ultraviolet rays, cosmic rays, and some chemicals can cause things like cancer)
• DNA (deoxyribonucleic acid), located in every cell’s nucleus, controls everything’s genetic information, like the formation of cells, what products they release, everything they do, and DNA is passed on from one generation to another.
  • The structure of DNA is similar to a coiled ladder (a double helix), where each side of the ladder is made of alternating subunits called sugars and phosphates.
    • The rungs of the ladder are pairs of of nitrogen bases that come in four different forms: guanine, cytosine, adenine, and thymine (G forms chemical bonds with C, and A bonds to T).
  • The sequence of bases or letters in DNA forms a code. It acts like a blueprint that controls the production of proteins in a cell. A section of the DNA molecule that codes for a specific protein is called a gene.
• Chromosomes are tightly coiled strands of DNA. Human somatic (body) cells generally contain 46 chromosomes, which are found in 23 pairs, with one copy of each chromosome coming from each parent. Other animals have different amounts of chromosomes.
  • In the process of mitosis, a somatic cell divides into two by copying all of its chromosomes before splitting up. The resulting diploid somatic cells each have 46 chromosomes, or 23 pairs.
  • In the process of meiosis, a somatic cell divides into two after copying and mixing all of its chromosomes, but then each resulting two somatic cells divide again into a haploid gamete cell containing only 23 chromosomes rather than the full 46.
  • There are two sex chromosomes: the large X chromosome and the smaller Y chromosome. Females have two X chromosomes, while males have have an X and a Y chromosome.
    • When females form eggs, each egg will get one of the X chromosomes. However when males form sperm, half of the sperm cells will get an X chromosome while the other half will get a Y chromosome. This makes the odds for the offspring’s sex to be about 50/50 upon forming a zygote.
  • Aging is most likely to be the result of chromosomes wearing out over time after each replication.
• Genetic engineering, a form of biotechnology, moves desirable genes from one organism to another for more desirable characteristics.
  • The human gene for insulin being moved into bacteria allows for the bacteria to produce human insulin as a waste product, and this can be done in large quantities too.
  • A transgenic organism is one in which human genes are added into its fertilized eggs.
  • The increasing demand for fish farming or aquaculture has resulted in scientists adding genes for disease resistance and growth to fish for more fish.
  • Genetically engineered plants have also been altered to be tolerant of herbicide, lowering costs and reducing the amount of weeds.
• Artificial selection involves some different techniques or technologies.
  • Selective breeding is when specific plants or animals with favorable traits are bred with each other.
  • Cloning creates organisms from cells.
  • Artificial insemination involves the artificial joining of the male and female gametes.
  • Vitro fertilization has selected male and female gametes fertilize in a controlled setting.
  • Genetic engineering directly alters the DNA of an organism.
• The theory of natural selection was initially proposed by Charles Darwin. The Galapagos finches provide the best example of this theory (the fittest or best-adapted organisms for a specific environment survive). The theory can be summed up in about four statements:
  1. All organisms produce more offspring than can possibly survive.
  2. There are significant variations within each species.
  3. Some of these variations increase the chances of an organism surviving to reproduce.
  4. Over time, the variations that successfully pass on lead to changes in the genetic characteristics of a species.
• In the last 600 million years of Earth’s existence, there have been five major extinctions. They are caused by things such as volcanoes, earthquakes, floods, fires, competition, or disease.
  • The rate of extinction is thought to be one species per day over the age of life on the plant, but today the rate is at about 70!
  • Extirpation is when a species goes extinct within a particular area.
  • Overspecialization, another cause for extinction, is caused by a species catering too much to a specific environment.
  • Insects have the highest biodiversity of any type of animal (the number of species).
• The human impact on the world’s species and biodiversity is massive, because of everything we do, from pollution to agriculture.
  • Mankind has has been the cause for the extinctions of many species of animals because of hunting, such as passenger pigeons.
• However, there have been efforts to assist with the protection and preservation of the world’s biodiversity:
  • Protected areas, such as a national parks or reserves, enforce additional rules.
  • Zoos originally began as private collections of exotic animals kept by the rich, but they then soon became primarily educational institutions and sanctuaries for the protection and preservation of endangered animals.
  • Seed banks are established to gather and store seeds from plants that are threatened with extinction. Some are run for selling plants, while others are were made for research purposes.
  • Global treaties have been drawn up to protect endangered plants and animals. Some laws make it illegal to buy or sell such animals (like rare birds, reptiles, amphibians, elephants, leopards, cheetahs, or rhinos), or their body parts.

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Matter and Chemical Change

• Matter can be described with properties, which are characteristics.
  • Qualitative properties describe characteristics using the senses. (color, state, texture, luster)
  • Qualitative properties describe characteristics using the numbers. (boiling point, melting point, solubility, density)
• Changes in matter can be put into two categories.
  • During a physical change, a substance changes in form, but not in chemical composition (no new substances are formed). (melting ice, chlorinated water)
  • A chemical change forms new substances, and they are often difficult or impossible to reverse. (burning paper, sulfur reacting with oxygen to form sulfur dioxide)
    • Chemical changes may occur along with some of the following signs: the production or absorption of heat, the depletion of the starting material, the changing of color, or the formation of gas bubbles, a precipitate, or a material with new properties.
• Relating to those changes, matter can also be described with some additional properties:
  • Any property that can be observed or measured without forming a new substance is a physical property. (density, color)
  • Any property that describes how a substance reacts with another when forming a new substance is a chemical property. (combustibility, toxicity)
• A theory is an explanation of an observable phenomenon supported by research (evidence), while a law is a widely supported explanation of what happens, without an explanation why.
• Throughout history, many people came up with different beliefs for the composition of everything.
  • Thousands of years ago, Empedocles thought that there were four elements: earth, wind, water, and fire. He believed that everything was a combination of these.
  • Not too soon later, Democritus suggested that everything was made up of different particles called atoms, which were indivisible and indestructible.
  • Sir Francis Bacon (1561-1626) stated that science should be based off of experimental evidence rather than thought, which was quite different to how things were usually done in his context. However, other parts of the world were already doing experiments.
  • Robert Boyle (1600s) recognized that elements could combine to form compounds, and that everything was made of the same universal matter and was only based on shape and motion.
  • Antoine Lavoisier proposed that elements are substances that can’t be broken down by chemical processes.
• The Law of Conversation of Mass says that in a chemical change, the total mass of the new substances is always the same as the total mass of the original substances. Mass doesn’t disappear.
• The Law of Definite Proportions says that compounds are pure substances that contain two or more elements combined together in fixed proportions. (water is always composed of one oxygen atom and two hydrogen atoms)
• There have also been numerous views of what atoms looked like throughout history, once it’s been established that everything is made of different amounts of different atoms:
  • John Dalton claimed atoms looked like billiard balls and were solid mass, where more mass meant a larger volume.
  • JJ Thompson used a cathode ray tube to determine that atoms were composed of charges, so atoms must have parts that are negatively charged. This is sometimes called the raisin bun or plum pudding model.
  • Ernest Rutherford discovered that there was a small mass in the center of the atom, while most of the rest of the atom is empty. He found this out by firing alpha particles at a very thin gold sheet. Most of the particles would go straight through the gold, and only a few were deflected.
  • Niels Bohr agreed with Rutherford but thought electrons must reside in specific orbits around the nucleus. He knew this because of studies of excited (energized) gases that would give off a specific color (frequency) of light.
  • The work of many scientists resulted in the refinement of the model of the atomic structure. They agreed that electrons have distinct energy levels, and that there was an area around the nucleus where electrons were most likely to be found, called the electron cloud. They also suggested that electrons are more likely to be closer to the center, and that their behavior could be described with mathematical equations.
• The process of decomposing an chemical compound by passing an electric current through it is called electrolysis. Electrolysis has been used to discover the compositions of compounds.
• Electrons (negative) and protons (positive) have exactly the same quantity of charge, but electrons are 1840 times smaller than protons. Neutrons are neutral (no charge).
  • The atomic number of an element is its proton number, while the atomic mass of an element is the mass of an atom where the mass of a proton or neutron is one, so the number of neutrons in an element is the difference between its atomic mass and atomic number.
• The periodic table of elements is used to represent all the known elements. The modern periodic table was developed by Dmitri Mendeleev.
  • Chemists use one, two, or three letters to represent elements, and the first letter is uppercase, while the rest are lowercase. (Zn is zinc, P is phosphorus)
  • The arrangement of information on a square of the periodic table of element can vary, but it will always have the element name, atomic number, symbol, and atomic mass.
  • The staircase is the line that forms the division between metals (left) and nonmetals (right). Metalloids are along the line.
    • Metals are solid at room temperature, except for mercury, which is liquid. They’re shiny and good at conducting. They’re also malleable (can be flattened into sheets without crumbling) and ductile (can be stretched into long wires).
    • Some nonmetals are gases, and some are solids, while bromine is the only liquid. They’re not very shiny and poor at conducting. They’re also brittle and ductile.
    • Metalloids are solids, where some are shiny, but others aren’t. Some of them conduct electricity, but they’re somewhat poor conductors of heat. They’re brittle and not ductile.
  • In addition to those three categories, there are also these four main families:
    • Alkali metals are very reactive, so they must be stored in oil to prevent water from coming into contact with them. They react with Halogens, as well as other nonmetals. The larger they get (down the table), the more reactive they get.
    • Alkaline earth metals are less reactive than alkali metals. Beryllium doesn’t react with water, magnesium slowly reacts, but calcium and larger will react with water, but not as violently as alkali metals. They also react with halogens along with other nonmetals.
    • Halogens are naturally found in compounds and naturally exist as diatomic molecules (pairs). The higher up on the table they are, the more reactive they are.
    • Noble gases are unreactive, so they’ll only react under very special circumstances, usually reverting immediately afterwards.
  • All elements above 93 are synthetic. They can only be formed in a lab for a very short amount of time.
  • The number of levels of electrons in an element is represented by the row (period). (hydrogen with one level is on the first row, lithium with two levels is on the second row)
  • The number of electrons in the outermost (valence) shell of an element can be found by counting its column. (potassium with one valence shell electron is on the first column, carbon with six valence shell electrons is on the sixth column)
• When an atom has more electrons than protons, it’s a negatively charged ion (anion), but if it has less electrons than protons, it’s a positively charged ion (cation).
• The maximum number of electrons per shell in an element is determined by the formula 2(n^2), where n is the level of shell, increasing as it gets further from the nucleus. (first = 2, second = 8, third = 18, fourth = 32, etc)
• IUPAC (Internation Union of Pure and Applied Chemistry) determines the (hopefully) universal standard used for naming everything, among other things.
• The octet rule states that atoms “like” to have eight electrons in their valence shell, so they’ll try to either take or give electrons until that state is reached. However, atoms with one level/layer want only two valence electrons. Because of this, compounds can be formed, and there are two types:
  • Ionic compounds are formed from at least one metal and at least one nonmetal. The metal gives off of electrons, while the nonmetal accepts electrons, such that both satisfy the octet rule.
    • Due to their high attraction, they have high melting points, boiling points, malleability, and conductivity.
    • An ionic compound’s chemical formula involves putting the element symbol for the metal(s) first, followed by the nonmetal(s). When there is more than one atom for the same element, a subscript with the number is put after the element’s symbol. (one sodium, one hydrogen, one carbon, three oxygen = NaHCO3)
    • Naming an ionic compound involves writing the metal name first, followed by the nonmetal with an “ide” ending. If there are more than three elements, then the name of the nonmetal polyatomic ion must be used. (two sodium, one carbon, three oxygen = sodium carbonate)
    • Transition metals (found in the middle of the periodic table) can have different electron configurations (levels), and therefore different charges. Because of this, a roman numeral is written after the metal. (two iron positively charged by three, three oxygen negatively charged by two = iron (III) oxide)
  • Molecular compounds are formed from covalent bonds between nonmetals. The nonmetal atoms will share enough electrons amongst themselves to fulfill the octet rule.
    • Due to their lesser bonds, molecular compounds have a low melting points, boiling points, and conductivity.
    • Diatomic molecules consist of two atoms of the same element together. (oxygen, nitrogen, hydrogen)
    • Writing chemical formulas for molecular compounds is pretty much the same as writing chemical formulas for ionic compounds, but since there’s no metal, there’s a special order: carbon, nitrogen, hydrogen, oxygen, halogens. (Candy’s Not Good, Old Hippie)
    • To name molecular compounds, the process is almost the same as for ionic compounds, except a prefix is needed to identify the number of each element: one is “mono”, “two” is “di”, three is “tri”, four is “tetra”, five is “penta”, six is “hexa”, seven is “hepta”, eight is “octa”, nine is “nona”, and ten is “deca”. For the first element, “mono” isn’t used. (CCl4 = carbon tetrachloride)
    • Some names are more recommended than their systematic name. (one oxygen, one hydrogen = hydroxide; one carbon, four hydrogen = methane; two carbon, six hydrogen = ethane, two hydrogen, one oxygen = water; two hydrogen, two oxygen = hydrogen peroxide; three carbon, eight hydrogen = propane; one nitrogen, three hydrogen = ammonia; three oxygen = ozone)
• Chemical reactions that give off energy are called exothermic, while reactions that take in energy are called endothermic.
  • Single replacement reactions involve a more reactive reactive element replacing a less reactive element. (K + LiBr -> Li + KBr)
  • Double displacement is the same, but two elements switch. (LiCl + KBr -> LiBr + KCl)
  • Synthesis is when two reactants make just one product. (Cl + Na -> ClNa)
  • Decomposition is when one compound breaks down into its elements. (ClNa -> Cl + Na)
  • Corrosion has a metal reacting with oxygen to produce a metal oxide, like rust. (2Fe + O2 -> 2FeO)
  • Combustion usually involves a hydrocarbon (carbon and hydrogen compound) reacting with oxygen to produce energy (like fire), carbon dioxide, and water. (CH4 + O2 -> CO2 + H2O)
• A catalyst helps a chemical reaction proceed faster, while an inhibitor helps slow down a chemical reaction.
  • Factors like surface area, temperature, and concentration can also help speed up or slow down chemical reactions.

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Environmental Chemistry

• The chemicals that animals need are called nutrients; they circulate throughout the body for energy, growth, building, and repair.
  • Organic (carbon-containing) nutrients are classed as carbohydrates (energy for metabolism), proteins (structural body molecule and chemical reactions for enzymes), lipids (unused chemical energy storage), and vitamins (help with enzyme function).
    • Enzymes regulate chemical reactions in living organisms.
  • Inorganic substances not destroyed by cooking or exposure to air are referred to as minerals. They’re distinguished by the amount needed: macrominerals are required at least 100 mg a day, while trace elements are needed less.
    • Many of the minerals we require are commonly found in Earth’s crust.
• Plants “extract” the minerals found in soil. In some cases, root hairs are able to produce mineral compositions up to 10,000 times greater than the soil around them.
  • Fertilizer provides an increased amount of nutrients for plants to boost the selfish desires of the evil human race. They benefit mainly by using high amounts of nitrogen, phosphorus/potash, and potassium/phosphate.
• Some organisms get their minerals by absorbing them from a substrate, a material on which the organism moves or lives. (lichens on a rock)
• Three types of pesticides (pest genocide) exist: herbicides for plants, fungicides for fungus, and insecticide for… insects.
• Ingestion involves taking in a material. For example, we eat. Absorption however, is when a material comes into contact with the digestive tract, respiratory tract, or skin.
• DDT (dichlorodiphenyltrichloroethane (one helluva mouthful)) is a chemical spray that’s meant to kill insect pests. Invented toward the end of the first World War, it was seen as one of the greatest advances in medical history.
  • In the 1950s and 1960s, DDT was responsible for seriously lowering malaria, bubonic plague, typhus, and yellow fever numbers, as it was sprayed everywhere, even indoors and on people.
  • However, DDT was also responsible for a dramatic rise in DDT amounts in animals, many of which are needed for a healthy ecosystem; this resulted in a cascading chain-reaction of problems. It also affected soil for many decades to come.
  • DDT was later banned in many places due to these reasons, but this resulted in a spike in disease cases, again (for Zanzibar malaria cases, 70% pre-DDT -> 5% post-DDT -> 55% post-ban)
    • The WHO (the World Health Organization) tested some other insecticides better for the environment, but none came close to DDT’s effectiveness, and they were much more expensive to produce.
• The pH (power of hydrogen) scale how acidic or basic a solution is, ranging from zero to fourteen; acids are lower on the scale (more H+ ions than OH- ions), seven is neutral, and bases are higher up (more OH- ions than H+ ions).
  • The pH scale is actually logarithmic, rather than linear. (pH 1 has a tenth of the concentration of pH 0 (10^(-1)), pH 3 has a thousandth of the concentration of pH 0 (10^(-3)))
  • An indicator indicates what something is. What did I just type up right now? For example, litmus is an indicator that’s a pink mixture of plant compounds extracted from certain lichens.
  • Acids are substances that produce an abundance of H+ ions when mixed in water. They contain hydrogen in a molecular bond with some non-metal element or polyatomic ion, and it acts as the metal.
    • Acids turn litmus red and are often known to sting and be sour.
    • Some examples of acids include battery acid (pH 0.5), lemon juice (pH 2), vinegar (pH 2.2), apples (pH 3), tomatoes (pH 4.2), normal rain (pH 5.6), and milk (pH 6.6).
  • Bases are substances that produce an abundance of OH- ions when mixed in water. They contain a metal as a cation and hydroxide as an anion.
    • Bases turn litmus blue and are often known to be slippery and bitter.
    • Some examples of bases include human blood (pH 7.4), baking soda (pH 8.2), the normal water of the Great Lakes (pH 8.5), milk of magnesia (pH 10.5), ammonia (11.1), and drain cleaner (14).
  • When an acid and base are mixed together, the H+ and OH- ions combine to form water, along with a salt. (HCl + NaOH -> NaCl + HOH)
• When we burn fossil fuels, we create gases that end up turning into acid rain, negatively impacting the environment; some organisms require a specific pH level in order to survive.
  • Buildings made of limestone react with acid rain, destroying the building. This is because limestone is a mild base that can neutralize the acidity.
  • In some places, the alkaline minerals in rock debris can neutralize acid rain, since they’re basic. Liming is the addition of basic calcium carbonate into the environment to neutralize acidic bodies of water.
• The catalytic converters in cars convert harsh oxides into less dangerous ones, primarily by two ways: splitting nitrogen oxides into nitrogen and oxygen, and reacting carbon monoxide with oxygen to produce carbon dioxide.
• Scrubbers in power plants react with dangerous oxides like sulfur dioxide by mixing water and lime (CaO and other calcium oxides) with exhaust gases to prevent acid rain formation, producing calcium sulfite and a sludge byproduct. (CaO + SO2 -> CaSO3)
• A pollutant is any material or form of energy that will cause physical, chemical, or biological harm to a living organism. Pollution is any alteration of the environment producing a condition that is harming to living things.
  • Dilution can make the effect of pollutants less apparent.
  • There are five zones in polluted water: the clean zone has high dissolved oxygen and low biochemical oxygen demand (trout, mayfly), the decomposition zone has medium dissolved oxygen and medium biochemical oxygen demand (carp, catfish, leeches), the septic zone has low dissolved oxygen and low biochemical oxygen demand (no fish, midge, larvae), the recovery zone has medium dissolved oxygen and low biochemical oxygen demand (carp, catfish, leeches, isopods), and then it returns to the clean zone.
• How much of a substance is present in another substance can be measured with PPM (parts per million), PPB (parts per billion), and other units. (76 grams of potassium iodide for every 1,000,000 grams of sodium chloride is a concentration of 76 ppm)
• A chemical has acute toxicity when serious symptoms occur after only one exposure (like methyl isocyanate), while chronic toxicity is diagnosed when symptoms appear only after a chemical accumulates to a specific level after many exposures over time (like lead poisoning).
  • The LD50 (Lethal Dose 50) refers to the dosage of a chemical that will kill 50% of the population to which it is applied. Most measurements regarding humans are collected as a result of accidents. (nicotine has a LD50 of 0.86 PPM)
    • Despite it being common, using rats or mice for testing isn’t always applicable to humans for LD50 measurements.
  • Thalidomide was originally developed as a sleeping pill, but in the 1950s and 1960s, it resulted in birth defects for thousands of babies.
• For every molecule for human-made pesticide, there are 10,000 molecules of naturally formed pesticides; every chemical has the potential to be harmful, too.
• Non-persistent pollutants can break down (fertilizers, sewage), while persistent pollutants accumulate in the environment, slowly breaking down, if at all (pesticides, petroleum).
  • Excess fertilizer in bodies of water result in “algal bloom”; when the excess algae dies, lots of dissolved oxygen is used in the process of decomposition.
• Pollution often lowers the ability of an environment to support life, as the amount of dissolved oxygen in the water has decreased. The population and biodiversity of some organisms can be observed. These species are known as biological indicators. (trout and perch tolerate low levels of pollution, carp and catfish tolerate high levels of pollution)
  • The most useful organisms for indicating water quality are macroinvertebrates: organisms large enough to be visible lacking a backbone. They’re therefore the focus of many stream surveys.
• Point sources for pollution are concentrated and come from one spot (drainpipes, smokestacks), while non-point sources are spread over a large area (feedlots, golf courses, construction sites, fertilized fields, acid rain).
• The acronym NIMBY is for the phrase “not in my backyard”, and it’s used as an opposition by the residents of an area to development and lack of land regulation.
• Many pollutants get transferred by winds in the air all around the world, often converging to the North.
• While ozone (O3) is an irritating toxin at the Earth’s surface, ozone high in the stratosphere prevents ultraviolet radiation fromr reaching the surface of the planet. Without this protection, biological organisms at the surface experience damage to cells.
  • CFCs (chlorofluorocarbons) are man-made pollutants that used to be used in products like Styrofoam, aerosol can propellants, and refrigerator and air conditioner coolants.
  • A hole in the Earth’s ozone layer was found in the South pole, and it was caused by CFCs reacting with ultraviolet light, producing chloride ions. These chloride ions act as a catalyst for the breakdown of ozone into normal oxygen gas (O2).
  • Since then, many countries have agreed to stop the production and use of CFCs to help, but by then, the hole over Antarctica was the size of the US. Meanwhile up top with Santa, ozone levels were 40% lower than normal.
• Many countries have enacted legislation to make it necessary for water to be treated before leaving the sewage system. Methods for removing microorganisms, pollutants, and other chemicals include chlorination and high-intensity ultraviolet light.
  • Primary treatment physically separates large solids and suspended sediments, secondary treatment removes organic compound using bacteria (resulting sludge is removed), and tertiary treatment removes nitrates and phosphates.
• The permeability of the rock and soil that groundwater goes through can affect the amount found underground. Useful amounts can be found by drilling a well into a someplace with an aquifer… a place with useful amounts of groundwater. However, contamination can be prevalent with aquifers, so it’s important to prevent it in the first place.
• While some things may be considered biodegradable, conditions may vary; temperature, humidity, microorganism quantity, oxygen level, and other factors can severely lengthen the decomposition process.
• Many hazardous substances, like household cleaning products, are solvents: they’re used for dissolving other substances.
• A sanitary landfill covers its waste each day to avoid windblown litter and scavengers. Liners are also employed to prevent fluids from filtering down into groundwater supplies.
  • Leachate is the result of decomposing wastes, and methane is the result of buried organic waste decomposing without oxygen (anaerobic biodegration). It’s usually burned in a controlled matter somewhere else.
• Secure landfills store hazardous and toxic wastes using liners, layers of gravel, seepage pipes, sand cushions, and even more thick walls and layers. It’s also capped by clay, plastic, and soil. Any possible leakage is also monitored by drilling wells.
• The use of living organisms, like mustard, fescue grass, and the familiar poplar tree, to fix problem like reducing pollutants is called bioremediation.
  • Container tanks called bioreactors house bacterial species known for breaking down persistent and toxic wastes to clean up groundwater being pumped in and out.

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Electrical Principles and Technologies

• An excess of protons in ions leaves a positive electric charge, and an excess of electrons in ions leaves a negative electric charge. Benjamin Franklin was the first to describe this, in the 1700s.
  • The Laws of Charges states that unlike charges attract, like charges repel, and charged objects attract uncharged (neutral) objects.
• The imbalance of electric charges in something is called static electricity. These charges will try to balance and even things out by moving over to neutrally charged things. (rubbing feet on a carpet before touching a doorknob, rubbing balloon on hair before touching a shirt)
  • The act of connecting an object to the Earth with a conducting wire is called grounding the object. This is possible because the Earth is so large (not as behemoth as your mom though) there’s enough electrons to neutralize or enough space to absorb.
• Conductors (like most metals) allow charge to travel freely by spreading electrons out, while insulators (like most non-metals) don’t allow charge to travel freely by tightening electrons together.
  • Semiconductors are materials in between conductors and insulators in terms of how freely electrons can move. Superconductors are past conductors in that they offer little, if any, resistance to the flow of charges by being subjected to extremely low temperatures.
• In a circuit, conductors allow for electricity to move around, sources are sources of electric energy (battery, solar panel), loads are the items along the circuit that convert electricity into other forms of energy (light bulb, motor, resistor), and controls are switches or devices that can turn the circuit or devices along it on or off (physical switch, transistor).
• The electric current is the amount of charge that passes a point in a conducting wire every second, measured in amperes, with the symbol I.
  • Really weak currents are measured with an galvanometer, and larger currents are measured with an ammeter or milliammeter.
• Voltage, or potential difference, is the difference in energy between one point in a circuit and another, measured in volts, with the symbol V. Voltage is measured with a voltmeter.
• Resistance to the flow of electricity is measured in ohms, symbolized by the Greek letter omega. Resistance is measured with an ohmmeter.
  • Resistors convert electricity into heat, introducing a specific resistance. Variable resistors’ resistance are controlled by external factors, like temperature, light, voltage, or a switch.
  • Resistance is also affected by the gauge of a wire conducting electricity.
• Ohm’s law states that resistance is equal to voltage over current, current is equal to voltage over resistance, or voltage is equal to current times resistance. (given the current in a circuit is 12.5 amps and the voltage is 120 volts, the resistance is 120 / 12.5 = 9.6 ohms)
• In a series circuit, there’s only one current path, and all moving charges travel through each component. In a parallel circuit there are multiple current paths, and the total current is divided, with some going through each branch.
  • In a series circuit, total voltage is equal to the sum of the individual voltage drops, components share the same current, and total resistance is equal to the sum of the individual resistances.
  • In a parallel circuit, components share the same voltage, the total current is equal to the sum of the individual branch currents, and total resistance is less than the individual resistances, such that Rtotal = 1 / (1 / R1 + 1 / R2 + 1 / Rn).
  • In houses, parallel wiring allows for all appliances to have equal energy. However, the more appliances connected, the more heat emitted from near the source.
• A thermocouple is a loop of two wires made of different types of metals that are wrapped together at both junctions (ends). When one junction is heated, a small electric current is produced.
  • A thermopile is a collection of thermocouples used to produce even more electricity.
• When a piezoelectric crystal like quartz is connected to a potential difference, it expands or contracts slightly (used in accurate clocks and speakers). The same thing is possible in reverse (like in the sparks of lighters).
• LEDs (light-emitting diodes) glow when electricity flows through them, and they last much longer with lower power than a traditional bulb.
• Photovoltaic (solar) cells are made of of semiconducting materials like silicon; when light is absorbed by the material, electrons break loose and flow freely, contacting metals that take in the current.
• In an electrochemical cell (battery), two electrodes of different metals are surrounded by an electrolyte (liquid electrolyte for wet cells, paste electrolyte for dry cells). For example, one electrode can be aluminum (anode), while the other is copper (cathode).
  • When the cell supplies current to a circuit, atoms of aluminum become ions and go into the electrolyte solution, slowly disintegrating the aluminum anode electrode. The negative ions go through the circuit and to the copper cathode electrode, slowly fattening it up.
  • Primary cells cannot be recharged, but secondary cells use chemical reactions which can be reversed, forcing electricity through the dead cell and rebuilding the original chemicals for reuse again.
• An electromagnet is a coil of wire wrapping an core (preferably iron), creating a magnet when current is passed through. An electric current is also generated when a magnet is moved along a wire.
• In an AC (alternating current) electric generator, mechanical forces turn an armature (rotating loop of wire) which is connected to the outside circuit via a split-ring commutator (a metal ring). Magnets around the armature induce a electric current in the wire.
  • With a DC generator, there’s instead a split-ring commutator, which is split so that the current is DC when the armature turns instead of AC with a slip-ring commutator.
  • Motors operate similarly, but electricity flows into the armature rather than from it.
• Alternating current for use in homes and industry is produced by large electric generators in power stations. Transformers are used to “step up” the voltage for efficient transmission over long distances, while at the destination, other transformers “step down” the voltage.
  • When electricity enters a building, a circuit breaker acts as a switch and safety device that can cut off power coming in if there’s too much. Older buildings sometimes instead have a fuse box.
  • Additional circuit breakers control each branch circuit in a building. Branch circuits are parallel cable wires that supply power to wall lights or plugs in walls. Branch breakers cut off current to branch circuits that get hot enough to start a fire.
  • The breakers, plugs, lights, and switches in each branch circuit are connected by electric cables that contain three wires: a white insulated neutral wire, a black insulated hot wire, and a bare copper/green insulated ground wire.
• Digital electronic technology involves machines that process numerically coded information. They primarily rely on transistors, integrated circuits, and microprocessors to represent numbers and letters using a binary code (note that this is a gazillion mile view from above of the whole field).
• In physics, power is defined as energy per unit time, so electric power describes the amount of electric energy that is converted into other forms of energy (heat, light, sound, motion) every second or the amount of electric energy transferred from one place to another in a certain amount of time.
  • The equation that defines power is Power (in watts) = Energy (in joules) / Time (in seconds), so a watt is a joule per second. A kilowatt is 1000 watts. Therefore, energy can also be calculated with Energy = Power * Time. (a 100 W light bulb converts 100 W of electric energy into light and heat every second)
  • Electric power can also be calculated with the equation Power (in watts) = Current (in amps) * Voltage (in volts). (the power of a heater when it is connected to a 110 V wall outlet with 13.6 A passing through is about 1500 W)
  • A kilowatt hour is the total energy supplied to a 1000 W load during an hour of operation. (a small hair dryer with a rating of 1000 W running for an hour would have transformed 1 kWh of electric energy into thermal energy)
  • The efficiency of a device is how much energy input becomes useful energy output, or Efficiency = Energy Output (in joules) / Energy Input (in joules). This can be converted into a percentage by multiplying by 100. (the efficiency of a 1000 W electric kettle taking four minutes and 196,000 joules of energy to boil water is about 81.7%)
• Most electricity is generated via large thermo-electric generating plants using non-renewable fossil fuels. Heat from burning stuff converts water into steam, and the high-pressure steam flows through pipes into a spinning turbine that turns a generator to produce electric energy.
  • Biomass, solid material from living things, can also be burned to power thermo-electric generators. They’re considered renewable because they can be continually replenished. (trees, crops, plants, wastes)
  • The continued use and want for fossil fuels has serious negative impacts on the environment. Open pit mining disturbs soil and vegetation, underground mines produce waste materials, water becomes contaminated, and burning fossil fuels produces contaminants in the air.
• Hydro-electric plants are dams that use water pressure to generate electric energy. Water is directed by a channel called a penstock from the bottom of a reservoir to a turbine. The rapidly flowing water turns turbines which turn electric generators, resulting in electricity. However, their construction causes lots of change to land, which is almost always harmful in some way.
• Thermonuclear electric generation uses nuclear fission (the splitting of atoms, usually uranium, releasing tons of energy) to heat water, generating steam. Again, the steam then turns a turbine connected to a generator to produce electricity. Radioactive waste in the form of used reactor fuel is released and can be very dangerous.
  • In the future, nuclear fusion might be useful (the joining of two atoms, like stars), to produce energy, as it doesn’t produce lots of radioactive waste.
• All thermonuclear and thermo-electric generating plants release some thermal energy into the environment. Thermal pollution occurs when warm water is returned directly to the bodies of water they came from, affecting organisms.
  • Cogeneration systems produce electricity and provide hot water or steam for industrial or commercial heating. This also helps prevent thermal pollution.
• There are other greener sources of energy too; windmills use wind to turn a turbine, solar farms use sunlight on solar cells, heating liquids via sunlight is also possible, ocean tides can also turn a turbine, and geothermal energy uses the steam from hot springs and geysers to rotate turbines.

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Space Exploration

• People back then originally noticed patterns with celestial bodies, like stars, planets, and moons. Constellations were groups of stars that stayed in the same positions relative to one another to form something recognizable. Beliefs and practices were also shaped around celestial bodies and their movements. (seasons, navigation, timekeeping)
• Celestial bodies were located in the sky by first getting an angle clockwise from north, called the azimuth (often done with a compass). Then, an angle called the altitude is measured from the horizon to a celestial body (often done with an astrolabe). These coordinates changed as time passed on and things move.
• The geocentric model of the Solar System has the Earth at the center, with all other bodies orbiting it. It was commonplace before we developed the models we have today. It was used mainly because it made sense that everything else other than us would be moving.
  • Pythagoras (570 to 490 BCE) found that the Earth was round, and so were the planets and the Moon.
  • Aristotle (384 to 322 BCE) believed that the Earth was at the center of the universe, while all other celestial bodies were attached to transparent spheres that rotated around the Earth.
  • Ptolemy (100 to 170 CE) explained retrograde motion (moving back and forth in the sky) and changing brightnesses with the idea that planets orbited in epicycles around a deferents.
• The heliocentric model of the Solar System had the Sun at the center, with all other bodies orbiting it. It was controversial at the time in Europe, thanks to the Roman Catholic Church.
  • According to my Eurocentric science textbook, Copernicus (1473 to 1543 CE) was the first documented scientist to have determined that the sun is the center of the Solar System. He published the book that proved it on his death bed for fear of reprisal from the Church.
  • Galileo Galilei (1564 to 1642 CE) supported Copernicus’s model after inventing his version of the telescope. He noticed many details in faraway planets and moons. He was then threatened by the Church for his beliefs, and was forced into house arrest after publicly renouncing his work.
  • Johannes Kepler (1571 to 1630 CE) came to work for Tycho Brahe, who made some of the most accurate and detailed star charts up to this time. He came up with the idea that planets moved in elliptical patterns, as opposed to circular patterns.
  • Later scientists refined this model with more discoveries or whatever.
• A solar eclipse occurs when the Moon blocks out the Sun’s light before it hits the Earth. A total solar eclipse results in complete darkness during the day. A lunar eclipse occurs when the Earth blocks out the Sun’s light before it hits the Moon. A total lunar eclipse results in a blood moon.
• A telescope is used to magnify objects at great distances. A simple refracting telescope uses a large objective lens and an ocular lens, or eyepiece.
  • The resolving power of a telescope is a measurement of the fineness of the detail the telescope can produce of the object in view. The larger, the objective lens, the higher the resolving power.
  • Reflective mirrors use an objective mirror instead of a lens to focus light. Refracting telescopes give better images at the same size, but reflecting telescopes can be made much larger.
  • A combination telescope incorporates both mirrors and lens in some eldritch horror of an amalgamation (a lens at the front and an objective mirror at the back).
• Celestial bodies orbit each other due to two opposing forces: gravity, pulling in bodies to massive bodies, and inertia, which is angular momentum.
• A spectroscope is a device that produces a spectrum of colors by passing in light through a narrow slit before a prism. Passing in sunlight reveals hundreds of black lines in the Sun’s spectrum (the solar spectrum); they’re called spectral lines.
  • When elements are heated to incandescence (the point where something begins to emit light), the spectrum produced by putting in the light through a spectroscope also has a set of spectral lines, unique to each element. Spectroscopy is a science involving the identification of the spectral lines of different elements.
    • It was then discovered that there are three types of spectra: emission or bright line spectra are black, except for some bright colored lines; continuous spectra have full and continuous colors; and absorption or dark line spectra are continuous, except for some black lines.
    • Unlike prisms which utilize refraction, diffraction gratings utilize diffraction to bend light around corners and produce spectra. It’s composed of thousands of closely spaced slits.
    • Spectral analysis has astronomers match the spectra of stars like the Sun with the spectra of different elements to find out what gases a star is composed of.
• The Doppler Effect is the change in frequency of waves when the thing that emits them is moving in different speeds and directions. This is caused by the waves, which can here be thought of as ripples, being compressed in the direction of the moving thing.
  • When a fast vehicle is moving towards you, it sounds high pitched, but when it’s moving away from you, it sounds low pitched, because the compression of waves changes frequency. A sonic boom is an explosive noise caused by the shockwave of sound energy coming from an aircraft moving at or faster than the speed of sound.
  • When a star is moving towards us, its light waves become compressed, of a higher frequency, and therefore experience a blueshift (a shift towards blue on the visible light spectrum). When a star is moving away from us, its light waves become more spread out, of a lower frequency, and therefore experience a redshift (a shift towards red on the visible light spectrum).
• Nowadays, telescopes are combined and controlled together using computers to generate much more detailed images. They also deal with refraction and blurring due to the Earth’s atmosphere using adaptive optics.
  • Phase cancellation is the reduction of wave interference by cancelling out waves with their opposite counterparts.
• The distance to distant stars can be measured by using triangulation (also known as the parallax technique). A viewer looks at the star from one angle and then looks at the star form another angle a specific distance away from the first point. Trigonometry magic is used to then find the distance to the star.
  • For more accurate readings, astronomers get a bigger baseline by waiting six months between looking at the star each time, since that would be the diameter of the Earth’s orbit around the Sun. Distant stars are used as a reference point since the star would then appear to move among them; this is called parallax.
• Astronomers use larger units of measurement, like an AU (astronomical unit), which is the distance from the Earth to the Sun (150 million kilometers), and a light-year, which is the distance the speed of light travels in a year (9.5 trillion kilometers).
• Visible light is part of the EMR (electromagnetic radiation) spectrum. It also includes radio waves, infrared waves, ultraviolet waves, X-rays, and gamma rays.
  • It was discovered that radio waves were coming from outer space and interfered with communication technologies. Aliens, obviously. They were strongest when they came from the Sun, followed by Jupiter.
    • Radio telescopes use radio waves instead of visible light to see celestial bodies. They can see much farther since radio waves can penetrate dust clouds, but their resolving power is weakened due to the lower frequency.
    • Interferometry is a technique where multiple radio and optical telescopes are used to get better images. Telescopes can also be put into space to work with telescopes on Earth to get a baseline twice as wide as Earth’s diameter!
• A rocket is a tube that throws combustible matter out of one end and carries a payload (explosive, satellite, person) at the other end up.
  • The exhaust velocity of a rocket’s exhaust is the speed it leaves the rocket (mind-blowing, I know). The higher it is, the faster the rocket is, however the more fuel there is, the heavier the rocket is.
    • Early rockets used solid fuel, like gunpowder, along with an oxidizer. Liquid fuel was then introduced for the ability to turn the engine on and off. They also have higher exhaust velocities.
  • Staged rockets have different parts that come apart and drop to lighten the rocket and be more fuel efficient.
  • Ballistic missiles are similar to bullets in that they don’t continuously combust fuel, but rather have an initial explosion, or something.
  • The power of computers are instrumental in controlling rockets, on ground, and in the spacecraft.
  • Gravitational assist is a method of acceleration which enables a spacecraft to gain extra speed by using the gravity of a planet. It gets in the orbit of a planet before it slingshots away from it.
  • Artificial satellites are devices made by humans to orbit some body, often the Earth. They can provide things like observation, communication, monitoring, navigation, and mapping.
    • Lots of space telescopes, like the Hubble Space Telescope and the recent James Webb Telescope, have been put into orbit to take very detailed images.
    • Geosynchronous orbit has satellites move at the speed the Earth rotates about 36,000 kilometers above the Earth, so it’s always directly over one part of the Earth. This is used to deliver continuous signals, though they can have a noticeable lag.
    • Low Earth orbit has satellites move much faster than the Earth (full rotation every 1.5 hours) 200 to 800 kilometers above the Earth, so it’s always directly over some different part of the Earth. This is used to get rid of the lag problems with Geosynchronous orbit satellites.
    • Satellites can also take pictures of the Earth to help map the world.
    • The GPS (Global Positioning System) was originally developed by the US military for navigation, but has since then been allowed for non-military applications. It has many satellites 20,000 kilometers above the Earth, such that there are always three in any part of the sky. It measures distance by using the time signals take to go to receivers on Earth and back.
• The Solar System consists of all the celestial bodies orbiting our Sun. The inner/terrestrial planets are the first four planets, and they’re all made of solid. The outer/jovian planets are the last four planets, and they’re all made of gas.
  • The Sun is a star, mostly of hydrogen. It’s about 1.4 million kilometers in diameter (110 more than Earth’s diameter), and it’s so hot that the gas glows, emitting the warm light we have on Earth. Nuclear fusion takes place there to produce temperatures of 15 million degrees Celsius.
  • Mercury, the closest planet to the Sun, has extreme temperatures ranging from 430 degrees Celsius to -180 degrees Celsius. It’s smaller and less massive than the Earth. It has a 58.6 day rotation.
  • Venus, the hottest planet, has a very thick atmosphere, and is almost the same size as the Earth. It’s average surface temperature is about 460 degrees Celsius. It has a 243 day rotation, and rotates in the opposite direction of the rest of the planets.
  • Earth, the only planet with life, has a habitable atmosphere and temperature, and lots of liquid water. It also has a moon, which the Apollo astronauts walked on a while back.
  • Mars, the red planet, has a surface consisting of mostly iron oxide. It has an average surface temperature of -50 degrees Celsius, a one day rotation, and two moons. There are a couple robots roaming around on it too.
  • Jupiter, the most massive planet, has a mass 2.5 times more than all the other planets combined. It’s Great Red Spot is a persistent high-pressure region. So far as of 2024, 95 moons have been discovered. Jupiter has an average surface temperature of -150 degrees Celsius and a rotation of 0.41 days.
  • Saturn, the planet with the distinct ring system, has rings composed of ice, rock, and dust. It has an average surface temperature of -180 degrees Celsius and as of 2024, 146 moons. It’s has a diameter 9.5 times larger than earth’s diameter.
  • Uranus, the weird planet, rotates at a 90 degree angle relative to the plane of the solar system. It has an average surface temperature of -210 degrees Celsius, and has rotation of 0.72 days. It also has 28 moons, and is about four times larger than the Earth.
  • Neptune, the coldest planet, has a surface temperature of -220 degrees Celsius and a rotation of 0.67 days. It has 16 moons, and is about four times larger than the Earth. It also has a Giant Dark Spot.
  • Pluto, the exoplanet, isn’t actually a planet, and is really far away. It also rotates in the opposite direction of the rest of the planets, and has five moons. It has an average surface temperature of -230 degrees Celsius. It has a rotation of 6.4 days.
  • Spacecrafts like Voyager 1 and Voyager 2 have travelled extremely far, and it takes a really long time to communicate with it.
• Galaxies are systems of stars, dust, and gas held together by gravity. We’re in the Milky Way galaxy.
  • A nebula is an interstellar cloud of dust, gas, and plasma created by both the formation and destruction of stars. It eventually collapses and eventually forms a star with a potential solar system. They’re also created from the remnants of old stars when they explode (supernovas).
  • Blue stars are the hottest stars, white and yellow stars (our Sun) are in between, and red stars are the coldest stars.
    • Stars eventually expand as they run out of fuel, located in their core.
  • Comets are formed further out in the solar system and are composed mostly of ice. They can have a coma as they get closer to the Sun (melting). Asteroids are formed closer to the inner part of the solar system and are composed of rock. There’s a giant asteroid belt between Mars and Jupiter. Meteors are asteroids that burn up in the atmosphere. A meteorite is one that makes it to Earth.
• During the Cold War, the former Soviet Union and the US competed in a sort of competition known as the Space Race. The two tried to outdo each other in the field of space exploration.
  • The Soviets were the first to send a satellite without astronauts into space (Sputnik 1), and the first to send a satellite with astronauts into space (Vostok 1). The Americans responded with the Freedom 7, which had a suborbital trajectory with an astronaut.
  • The goal of the American Apollo program was to send a three-person team to the Moon, land two of them, and bring everyone back safely. In 1969, Apollo 11 carried the first humans to the surface of the Moon.
  • Later, tensions eased and the Soviets and Americans had a joint mission that would link two spacecrafts together. They had different systems for life-support, like with air, and together they worked out details that worked better.
  • The Space Shuttle is a reusable spacecraft that gets carried by rockets and sometimes planes to get into space. This lowers costs, since new spacecrafts don’t always have to be built every time.
  • The ISS (International Space Station) is probably the largest and most complex international scientific project ever undertaken. It’s a space station orbiting the Earth with many laboratories for international research. It has been built with collaboration from well over a dozen nations.
    • The Canadarm is a giant robot space arm built by the CSA (Canadian Space Agency) connected to the ISS to help with spacewalks, repairs, and movement. Another one (the Canadarm2) was also built, and it has a hand aptly named the “Canada Hand”.
    • The term “microgravity” is used in the ISS instead of “zero gravity” because it’s in orbit (constant free fall around the planet).
    • There are lots of complex systems that work together to maintain the way everything is aboard the ISS. Scrubbers remove carbon dioxide from air, electrolysis splits water into oxygen and hydrogen, and all used water is recycled and used again.
    • ISS astronauts need to do a couple hours of physical activity every day, since the lack of gravity means a loss in bone mass and heart strength all the time compared to Earth.
    • Compared to the Earth’s magnetic field and atmosphere, the ISS protects against charged particles and electromagnetic radiation with its hull. It’s also well insulated.

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