Solar+Energy+2012

=Solar Energy Overview= toc The Solar Energy Module consists of four investigations that allow students to experience solar energy first hand and to investigate the variables that affect solar-energy transfer.

Objectives:

 * 1) become aware of the potential of solar energy, an inexhaustible source, as an alternative energy source to fossil fuels, a nonrenewable resource
 * 2) observe differences in size and position of shadows as a result of the relative positions of Earth and the Sun
 * 3) gain experience using a compass to orient objects on Earth
 * 4) become proficient in using a thermometer to monitor temperature change in a variety of materials
 * 5) observe solar-energy transfer in a variety of situations
 * 6) relate the rate and amount of temperature change to variables involved in energy transfer
 * 7) design solar water heaters and passive solar spaces heaters
 * 8) apply mathematics in the context of science
 * 9) acquire vocabulary associated with solar energy and energy transfer
 * 10) use scientific thinking processes to conduct investigations and build explanations: observing, communicating, comparing, organizing, and relating

Vocabulary List

Vocabulary Games

Audio Podcasts of Solar Energy Stories

Investigation 1

 * Light travels in a straight line.
 * Shadows are the dark areas that result when light is blocked by an opaque object.
 * The length of a shadow depends on the position and orientation of Earth relative to the Sun.
 * The lengths of shadows on Earth change as the Sun's position in the sky changes during the day due to the Earth's rotation.

Investigation 2

 * Change of energy from one form to another or from one object to another is called energy transfer. The law of conservation of energy states that energy can not be created or destroyed, only changed from one form to another.
 * Energy from the Sun is absorbed and released by different materials at different rates.
 * A heat sink is a material, such as water, that can absorb a large amount of heat for its volume and release the energy slowly.
 * A thermometer is a tool that can be used to measure the temperature (amount of heat) of a solid, liquid, or gas.

=Cosmology= Cosmology is the study of the nature of the universe as a whole entity. The word cosmology is derived from the Greek //kosmos// meaning harmony or order. Cosmologists are interested in the formation, evolution and future of the universe and its constituents.

Most objects we can see with telescopes are large or exist at extreme distances (e.g. planets, stars, galaxies, clusters of galaxies and even superclusters). The majority view of cosmologists is that all these objects were formed after an initial, extremely hot and dense formation event, about 14 Gigayears ago, that has created (and continues to create) the space we see around us. This event is called the Big Bang.

Whilst the hot Big Bang model does seem to explain much of what we observe around us, there are still many fundamental questions that exist. What is the majority of the matter in the universe made of? How common are planets around stars? What causes some galaxies to be elliptical, spiral or irregular in shape? What is the geometry of the universe? What is the mysterious dark energy? Is there a cosmological constant? Is it a variable? Do other universes exist?

=The Sun= The Romans called the sun Sol, which in English means sun. In ancient Greece, the sun was called Helios. Our Sun is not unique in the universe. It is a common middle-sized yellow star which scientists have named Sol, after the ancient Roman name. This is why our system of planets is called the Solar System. There are trillions of other stars in the universe just like it. Many of these stars have their own systems of planets, moons, asteroids, and comets. The Sun was born in a vast cloud of gas and dust around 5 billion years ago. Indeed, these vast nebulae are the birth places of all stars. Over a period of many millions of years, this gas and dust began to fall into a common center under the force of its own gravity. At the center, an ever growing body of mass was forming. As the matter fell inward, it generated a tremendous amount of heat and pressure. As it grew, the baby Sun became hotter and hotter. Eventually, when it reached a temperature of around 1 million degrees, its core ignited, causing it to begin nuclear fusion. When this happened, the Sun began producing its own light, heat, and energy. It gets energy from thermonuclear reactions in the core. On the sun's surface there are sun spots. They are created by magnetic energy that has come up through the sun's surface and lowered the temperature on the surface .At the core of the sun it is 27,000,000 F. The sun gives off many different kinds of radiation such as radio waves, x-rays, and ultra violet rays.

Thermonuclear fusion is the process in which a star produce its light, heat, and energy. This happens at the core of the star. The core is superheated to millions of degrees. This heat travels towards the surface and radiates out into the universe. Through this thermonuclear process, stars "burn" a fuel known as hydrogen. The result is that they create another type of fuel known as helium. However, stars do not burn in the same way that a fire does, because stars are not on fire.

Let’s see how the energy of the Sun moves from its inner core to the outer regions of its atmosphere. The CORE of the Sun is where energy is first formed. Its temperature is 27 million degrees Fahrenheit. From the core, energy moves outward toward the Sun’s surface and surrounding atmosphere. The energy moves through several layers or zones. Remember the Sun’s layers are made of hot gases and they not solid like the Earth’s layers. The energy moves out from the core through the
 * Structure of the Sun**

RADIATIVE ZONE. Scientists calculate the temperature to be cooler than the core—it is only a 4.5 million degrees Fahrenheit. That’s HOT! The Sun’s next layer is the

CONVECTION ZONE. Convection is how energy moves from the inner parts of the Sun to the outer part of the Sun that we see. We can see convection when we look at a pot of boiling water. Convection is what makes large, slow moving bubbles form in a bowl of hot miso soup. Through convection the heat moves from the bottom of the hot soup to the soup’s surface where it is cooler. The Sun’s convection zone is a bubbling 2 millions degrees Fahrenheit. The

PHOTOSPHERE, the Sun’s visible surface, is the next layer of the Sun. The bubbling motion of the convection layer makes the granular patterns we see on the photosphere. The granules may look small in pictures, but scientists estimate they are really about the size of the Moon. Sunspots—indicating giant magnetic storms—are also visible on the photosphere. Most of the time sunspots come in pairs—like the poles of a magnet. Even though sunspots are very, very hot they look darker than the rest of the Sun because they’re cooler. This layer of the Sun has cooled off to 10,000 degrees Fahrenheit and the Sunspots are even cooler—about 7,800 degrees F. Just above the photosphere is the

CHROMOSPHERE with huge solar flares and loops of hot gases shooting up thousands of miles. Things begin to heat up again here—the temperature is estimated to be 50,000 degrees F. And above the chromosphere is the

CORONA—we can only see it during a total solar eclipse. The corona is very, very hot—4 million degrees F. It is also very thin. Scientists are still trying to figure out why it is hotter than other parts of the Sun. This is a big mystery…

=Sun Spots= We don't often think of the Sun as having cooler areas on its surface. The Sun is far too hot for an astronaut to ever visit, but there are areas which are slightly cooler than others. These areas are known as sun spots. Sun spots are still very hot. However, because they are slightly cooler than the rest of the surface of the Sun, they appear slightly darker in color. The gravitational forces in Sun spots are also stronger than the other hotter areas. Of course, you cannot look directly at the Sun to see these spots because you would damage your eyes. Astronomers have to use special telescopes with filters and other instruments to be able to see the cooler spots on the surface of the Sun.

=Convection= Heat rises, while cooler gas falls. Have you ever noticed that your basement is always much cooler than upstairs. The same laws of physics apply within stars. Because heat rises while cooler gases fall, the gas within a star is constantly rising and falling. This creates massive streams of circular motion within the star. This is called convection. As the gases near the core of the Sun are heated, they begin to rise towards the surface. As they do so, they cool somewhat. Eventually they become cool enough that they begin to sink back down towards the core. It can take an atom millions of years to complete one complete cycle around a convection stream. As a result of this process, the temperature on the surface of the Sun is around 10,000 degrees Fahrenheit, which is much cooler than its superheated core.

= =

How do shadows form?
You can watch the effects of the sun's movement around the earth by observing shadows throughout a day. A shadow occurs when an opaque (not able to be seen through) object blocks light from the sun or other light source. Observing the behavior of shadows is an easy way to investigate some of the properties of light.

In the morning, just as the sun rises in the East, the shadow is long and points towards the West. The shadow shortens until the sun reaches it's highest point in the sky. As the sun travels on it's journey West, the shadow lengthens and steadily swings farther and farther East.

As the year passes and the seasons change, so does the sun's path in the sky. During December in the Northern Hemisphere the path of the sun is not very high In the sky. The shadows made in winter are the longest shadows you will see all year.

Points to understand include:
 * Light travels in straight lines
 * A shadow of an object will move due to either the motion of the object or of the light source
 * Even seemingly transparent objects can form shadows if they absorb or reflect some of the light striking them.

What is a Compass Rose?
The compass rose has appeared on charts and maps since the 1300's when the portolan charts first made their appearance. The term "rose" comes from the figure's compass points resembling the petals of the well-known flower.

A compass always points to the north and can be used to determine direction.

How does the sun move?
In ancient times, as people watched the sun move across the sky each day, they thought that the sun traveled around the earth. Scientists later found out that the sun remains in one place while the earth and the other planets travel around it. But we know now that the sun moves too!

The sun is just one star in a huge group of stars called a galaxy. Our galaxy, called the Milky Way, is spinning around like a phonograph record. And the sun is traveling around the center of the galaxy at a speed of about 481,000 miles per hour. At that speed, the sun will travel around the center of the Milky Way once in about 225 million years.

The Milky Way itself is moving around the center of a group of galaxies, like a planet moving around the sun. And this group of galaxies may be traveling around the center of the universe. So the sun is really moving in two or three directions at once!

Like the sun, all other stars are traveling through space at high speeds, but they’re so far away that to us, they look like they never move!

solar eclipse interactive: http://teacher.scholastic.com/activities/science/moon_interactives.htm

Day and night happen because the Earth rotates once on its axis every twenty-four hours. Day occurs when our side of the Earth faces the Sun and night occurs when our part faces away. As the day progresses, the Sun appears to follow a path from its rising in the east to its setting in the west. Important points to understand include:

The Sun appears to move across the sky due to the rotation of the Earth about its axis.The Sun's path for a certain day is determined by the location of the observer on the Earth.Shadows that form in the morning and late afternoon will be longer than the shadows that form at noon. As you move closed to a light source, shadows get shorter in length. As you move further away from a light source, shadows get longer in length.

Astronomy
Important people in the field of astronomy include:

The ancient Greek astronomer and mathematician **Claudius Ptolemy** (AD 90- 168) set up a model of the solar system in which the sun, stars, and other planets revolved around Earth. Known as the Ptolemaic system, it remained in place for hundreds of years, though it turned out to be flat wrong.

In 16th century Poland, astronomer **Nicolaus Copernicus** (1473-1543) proposed a model of the solar system that involved the Earth revolving around the sun. The model wasn't completely correct, as astronomers of the time struggled with the backwards path Mars sometimes took, but it eventually changed the way many scientists viewed the solar system.


 * Tycho Brahe**, whose defining physical characteristic was no doubt his metallic nose (he lost his real one in a duel), was a famed Danish astronomer. Up until his observations, which occurred largely in the late 1500s, no other astronomer had tallied as many, or as accurate of observations as Brahe. He catalogued hundreds of objects, and aspired to a level of accuracy such that each star was catalogued within one arc-minute of its real celestial location.

Using detailed measurements of the path of planets kept by Danish astronomer Tycho Brahe, **Johannes Kepler** (1571-1630) determined that planets traveled around the sun not in circles but in ellipses. In so doing, he calculated three laws involving the motions of planets that astronomers still use in calculations today. Born in Italy, **Galileo Galilei** (1564-1642) is often credited with the creation of the optical telescope, though in truth he improved on existing models. The astronomer (also mathematician, physicist and philosopher) turned the new observational tool toward the heavens, where he discovered the four primary moons of Jupiter (now known as the Galilean moons), as well as the rings of Saturn. Though a model of the Earth circling the sun was first proposed by Copernicus, it took some time before it became widely accepted. Galileo is most widely known for defending the idea several years after Kepler had already calculated the path of planets, and Galileo wound up under house arrest at the end of his lifetime because of it.

Building on the work of those who had gone before him, English astronomer **Sir Isaac Newton** (1643-1727) is most famous for his work on forces, specifically gravity. He calculated three laws describing the motion of forces between objects, known today as Newton's laws.

Heating the Earth
The sun has produced energy for billions of years. Solar energy is the sun’s rays (solar radiation) that reach the Earth. This energy can be converted into other forms of energy, such as heat and electricity. Energy from the sun is //free//. It's also //clean//, meaning it causes no pollution. Since the sun gives off more energy than we would ever need, it's //renewable//. It will never run out.

The sun radiates it solar energy into space in all directions. A very small amount of this solar energy reaches the Earth. About 90% of the energy reaching the surface of the Earth is visible light energy that we can see and infrared energy that we can feel when it hits our bodies or objects that we touch. Earth's surface (land and water) absorbs about one half of this energy, Earth's atmosphere absorbs about one sixth and the remaining one third of the energy is reflected back into space.

When an object absorbs light, the object becomes warmer. In the process light energy transforms into heat energy. This energy transfer changes the temperature of the material. http://www.wisc-online.com/Objects/ViewObject.aspx?ID=SCE304 Some of the energy that is absorbed by Earth is re-radiated from the surface as infrared radiation (heat energy). The water vapor and gases in the Earth's atmosphere trap some of the re-radiated heat and helps to maintain a fairly uniform global temperature.

Often the concepts of heat and temperature are thought to be the same, but they are not.Perhaps the reason the two are usually and incorrectly thought to be the same is because as human beings on Earth our everyday experience leads us to notice that when you add heat to something, say like putting a pot of water on the stove, then the temperature of that something goes up. More heat, more temperature - they must be the same, right? Turns out, though, this is not true.

The atoms and molecules in a gas are in constant motion. Temperature is a measure of the speed with which they move. (More exactly it is a measure of their .) The higher the temperature, the faster the molecules move.

The surface of our planet is about three-fourths water and one-fourth rock. The solid earth materials that make up the continents absorb the Sun's energy differently than water. Land surfaces heat up more quickly when exposed to solar energy and reach higher temperatures than water surfaces. During the night, when the earth's surface is not being subjected to solar energy, land surfaces cool off more quickly and reach much lower temperatures than water surfaces. The difference in the amount of solar radiation absorbed by land and by water results in temperature differentials that influence the movement of air masses, a powerful force affecting global weather.

There are a number of reasons for the temperature differences between land and water. More heat is required to warm a volume of water than to warm an equal volume of water than to warm an equal volume of almost any other substance. Water requires five times as much heat energy as solid rock to rise the same number of degrees.

A heat sink is any cool mass that can absorb excess heat, including bodies of water, the ground, and massive building materials. Water is a very good heat sink because it has a big capacity to absorb and store energy. It is a particularly effective heat sing because it releases energy slowly when the energy source disappears. Other reasons for the temperature differences between land and water include: These differences between land and water have interesting effects on climate. Coastal cities enjoy a moderate climate, usually without temperature extremes. Inland cities experience a greater range of temperatures through the seasons.
 * land is opaque, water is transparent. Solar radiation can penetrate water so the hear is distributed to a greater depth than on land.
 * land is solid while water is usually liquid. Heat moves slowly though rock by conduction and quickly through water by mixing.
 * some of the solar energy absorbed by water is lost during evaporation.