Subtest II: Science Study Guide for the CSET Multiple Subjects Test

Earth and Space Sciences

Earth and space sciences study the , atmosphere, hydrosphere, and lithosphere, to understand the origin and dynamics of the Universe, the Solar System, and Earth.

The Solar System

The Solar System is a planetary system of the Milky Way galaxy that is found in one of its arms, known as the Orion spur. It consists of the Sun, eight planets and their satellites, asteroids, comets and meteoroids, dust, and interplanetary gas.

Components

The components of the Solar System are the following: the Sun (a star that contains more than 99% of the mass of the system), planets (divided into inner planets and outer or giant planets), dwarf planets (spherical bodies with other objects in the same general orbit), satellites (large bodies orbiting planets), asteroids (minor bodies mainly located in the asteroid belt between Mars and Jupiter—their low mass doesn’t allow them to have a spherical shape), Kuiper belt objects (frozen external objects in stable orbits just beyond Neptune), and comets (frozen small objects coming from the Oort cloud, a region far beyond Neptune).

Time Zones

Time zones are 24 areas into which Earth is divided. They start from the prime meridian of longitude zero that passes through the Royal Observatory of Greenwich (it’s also known as the Greenwich meridian) in the south of England. In a time zone, all clocks tell the same hour, and between one time zone and the next, there is a difference of one hour. There are regional differences around the world. In the scientific model in which the time zones are based, each time zone covers 15° of longitude, adjusted for local political boundaries.

Sun, Moon, and Star Positions

Earth is constantly moving. One of its movements is rotation. This movement produces the impression that the heavens rotate around our planet, generating the succession of days and nights and the movement of the stars. The different seasons are the result of the 23°27’ inclination of Earth’s axis with respect to the plane of the elliptic, making the angle of incidence of the solar radiation—and therefore its strength—change with time in the different regions of the planet.

Bodies

The different bodies in the universe can be classified according to whether or not they emit light. Stars are the most common bodies that emit light and can be classified according to the type of radiation they emit using the Morgan–Keenan (MK) system. There are seven types of stars: O, B, A, F, G, K, and M. The bodies that do not emit light are classified according to their size as planets, satellites or moons, asteroids, meteoroids, and cosmic dust.

Geology

The word “geology” comes from two greek terms: geo (earth) and logos (study). Thus, it is a science that studies the composition and origin of Earth and the materials that form it internally and externally.

Rocks and Minerals

A mineral is an inorganic solid of natural origin, with a defined chemical structure and a defined physical structure (crystalline structure) that is found in the form of crystals. A rock is an inert natural substance that is composed of two or more types of minerals.

Formation—Rocks are classified according to how they are formed. Igneous rock is formed when molten lava (above ground) or magma (below ground) cools and solidifies. Sedimentary rock is formed when pre-existing rock is eroded and the resulting fine material accumulates in layers in oceans and lakes and eventually hardens. Metamorphic rock is formed when pre-existing rock is transformed by heat and/or tremendous pressure.

Characteristics—The observable physical characteristics of rocks and minerals are hardness, brightness, color, streak (the color of the pulverized mineral), cleavage and fracture (how the object breaks), density, solubility, and crystal structure.

Landforms

A landform is a distinct feature that is part of a larger terrain. There are many types of landforms, such as plains (flat land with slight undulations), mountains (generally considered to be land formations with an elevation of 610 meters or higher, but that isn’t a universal standard), mountain ranges (interlaced mountains), hills (raised land formations with a lower elevation than mountains), and plateaus (flat area elevated above the surrounding area with a sharp rise on at least one side).

Processes of Change

The landscape can undergo a series of changes that result in the destruction of some landforms and the creation of others.

Weathering—There are two types of weathering. In chemical weathering, the rocks react with water to dissolve or change from one type of mineral to the other. In physical weathering, the rocks are mechanically broken into smaller rocks.

Erosion—In erosion, rock and soil are moved by factors such as water and air.

Deposition—In deposition, the eroded fragments are deposited in the low elevations of continents and in the oceans. The deposits can accumulate and after millions of years may form sedimentary rocks.

Others—Other processes where the landscape changes include earthquakes and volcanic activity.

Formation and properties of soil—Soil is a mixture of inorganic components—sand, silt, and clay wethered from rocks—and organic components, such as the partially decomposed remains of plants and animals. The types of soil range from desert sand, with no organic matter, to peat, with no inorganic matter. The organic portion is what makes soil fertile. The factors affecting soil formation are climate, time, biological activity, and the original rock type, with climate being the most important. Some terms you should be familiar with are humus, soil profile, soil horizon, subsoil, and topsoil. Soil types you should know include loam, laterite, pedalfer, and pedocal.

Earth Layers

Earth is split into layers. The crust is the most external and thinnest layer. It is composed of a continental crust, which forms the continents and the shallow zones of the ocean, and an oceanic crust. The mantle is the second layer; it is 2,900 km deep and has a high temperature of 3,400°C. The core is the innermost layer. It is composed of a solid internal core made of an alloy of iron and nickel, and a fluid external core made of iron, nickel, sulfur, silicon, and oxygen.

Plate Tectonics

Plate Tectonics is a unifying theory that explains a variety of geological characteristics and events. It is based on a simple model of Earth that shows that the rigid lithosphere is fragmented, forming a mosaic of diverse pieces of different sizes in movement called plates which move slowly over the semi-molten mantle.

Source—Due to the poor thermal conductivity of the crust, the heat that is generated in Earth is accumulated below the crust and heats the mantle, generating thermal convection. The tectonic plates move passively on the convection currents.

Evidence—The study of the ocean floor has given the most reliable data to support the theory of plate tectonics. On the ocean floor there are “bands” of different magnetic polarity, called magnetic bands, that are aligned with the ocean ridges and symmetrically distributed at both sides of them. Each band reveals information about when and how the ocean floor was formed, providing evidence for plate tectonics.

Effects—The plates can diverge (separate), converge (join together), or slide laterally against each other. The result of this movement is most of the seismic and volcanic activity of Earth. This movement is also responsible for the formation of the mountain ranges.

New Creations/Big Events

The displacement of magma generates volcanoes and earthquakes of varying magnitude. When two plates slide against each other, the accumulated strain liberates suddenly and violently, producing earthquakes. When two continental plates collide, a mountain range is formed, and when an oceanic plate and a continental plate collide, oceanic trenches are formed. When two plates collide, the thinner or denser of the two sinks, producing earthquakes, volcanoes, and thermal features such as hot springs.

Minimizing Effects

Human activity, like mining, fracking, and dam building, can remove materials from the crust, causing instability that then leads to collapses that trigger earthquakes. That movement can generate earthquakes which are frequently harmful to humans. For this reason, there is a need for the development of technological solutions that will minimize these effects, such as the use of energy sources that do not require drilling or digging.

Meteorology

Meteorology is the science that studies and predicts the phenomena that occur in Earth’s atmosphere. This science further seeks to understand the phenomena’s behavior, composition, structure, and evolution to predict future events.

Influences

There are a series of factors and elements that have influence over the climate and weather. Some of them are explained below.

The Sun—The Sun is the main source of energy for every process in Earth’s climate system. Each element in this system absorbs solar energy and radiates it in the form of heat in every direction. The Sun also influences the temperature of a certain region.

Oceans—Oceans have a decisive influence on the characteristics of the climate in a given region. Water absorbs heat and releases it more slowly than the earth, so it can make the climate warmer and wetter in some months and cooler in others.

Water cycle—The water cycle is the movement of water throughout Earth. Energy in the form of heat can change the physical state of water.

Causes and Effects

There are five elements of climate that explain the weather (the status of the atmosphere in a particular location and moment): temperature, humidity, atmospheric pressure, wind, and rainfall. Conversely, climate (general weather patterns over long time periods) dictates the typical weather patterns for a region and is affected by six factors: altitude, latitude, land relief, proximity to the sea, vegetation, and marine currents.

Air movements—Air movement is generated by the differences in temperature that exist when there is uneven heating across the earth and in the atmosphere. The warmer masses of air tend to ascend, and its place is then occupied by cooler air masses. These movements of air that are driven by heat energy are called convection currents.

Ocean currents—The movements of masses of water are generated by changes in density in deep water regions. Those changes in density come from variations in the salinity and temperature of ocean water. The denser water will sink, while less dense water will float on top. Earth’s rotation imparts a circular movement to ocean currents due to what is known as the Coriolis effect.

The Role of Technology

Meteorology is not an exact science. The variables are so numerous that an exact prediction of the weather is difficult. However, newer technologies are helping us better forecast the weather and understand the climate. Radio probes, satellites, radars, and automated stations provide data that is analyzed by computers to predict the future conditions of the atmosphere and help humans prepare for adverse weather conditions.

Oceanography

Oceanography is the science that studies the characteristics of the sea, the relationship between Earth’s hydrosphere and the atmosphere, the chemical constitution, temperature, and movement of water, and the organisms that inhabit the bodies of water.

Bodies of Water

A river is a natural current of water that flows continually. A lake is a mass of water that is located away from the sea. An ocean is a part of Earth’s surface that is occupied by salt water and separates two continents. An estuary is the widest and deeper part of a river mouth where the fresh water from the river joins the salt water from the sea.

The Tides

A tide is the periodic change in sea level, produced by the gravitational forces from the Moon and the Sun. There are two main terms used in describing tides: high tide, which is the moment when water reaches its highest height, and low tide, which is the moment when water reaches its lowest height. The coastal topography influences the height during high tide. You should be familiar with the terms spring tide and neap tide, which refer to the variation in the height of the tides caused by relative positions of the sun, earth, and moon.

The Water Cycle

The water cycle is the sequence of phenomena by which water goes from Earth’s surface to the atmosphere in the form of vapor, and returns in its solid or liquid phases. The movement of water in the hydrological cycle is driven by the radiant energy from the Sun and the force of gravity. It begins with the evaporation of water from the surface of the ocean. As it rises, the humid air cools and the vapor is transformed into water (condensation). The raindrops join together and form a cloud. Then, they fall by their own weight (precipitation). If the atmosphere is too cold, the water falls as snow or hail. If it is warmer, it will fall in the form of rain. Transpiration, or the movement of water through and out of plants, is a major factor in the water cycle.

The Hydrosphere

Earth’s hydrosphere interacts with the planet’s other major systems through the water cycle. Water in the atmosphere moves water from oceans, water in the lithosphere generates erosion by weathering rocks and transporting fragments, and water in the biosphere is used by plants for the photosynthesis process, which is the basic energy-transforming process in living beings.