Familiarizing our students with astronomy terms enhances the learning experience. Before you initiate this unit, be certain to create a word wall to highlight many of the terms that will be used throughout this study. (Many of the words contained herein are included in non-fictional children's book selections highlighted in the bibliography.) To enhance my word wall, making it user-friendly and experiential for young learners, I include several 4" x 6" laminated color copied photos and/or diagrams (see "*" below) to highlight specific terms as visual vocabulary cues. Images, many of which are provided by NASA, can be downloaded and copied from the web. These items are public domain and can be used as long as they are utilized for classroom purposes.
Word Wall Selections
(table available in print form)
Young Explorers Want To Know!
In addition to providing researched information and related projects for my students, I always take into consideration areas of study that
want to pursue. I want my students to have an in-depth understanding of our topic of study. Providing them with an opportunity to give input in the curriculum fosters ownership, involvement, and understanding. The questions that follow are inquiries made by second graders with whom I have interacted. In those instances where abstract concepts sparked additional inquiry, I have included a "Related Activity/Resource" to bring understanding of the concept to life.
Before getting into the unit, inform your students to never look directly at the Sun. Highlight that the Sun is very powerful. Its rays can damage our cornea, the part of the eye through which light passes that along with other components, help us see. Emphasize that directly looking at the Sun can permanently damage our eyesight, causing blurred vision or blindness.
The Adventure Begins
The implementation of this unit spans eight to ten weeks, during which time 32 questions will be explored (see Pacing Calendar, Appendix A). This time frame can be shortened or extended as required.
(1) What is the Sun, and what is its age?
The Sun is a gaseous, luminescent sphere that emits light and heat energy, and magnetic force. Comprised predominantly of hydrogen and heliumthe same lightweight gases that cause zephyrs and party balloons to float in the air, small amounts of oxygen, nitrogen, carbon, and metallic substances comprise this sphere. Our Sun is an estimated 4.5 billion years old!
(2) How large is the Sun?
The Sun is approximately 865,000 miles in diameter. It is so enormous that approximately 1.3 millions Earths can fit within it!
(3) How far away are we from our Sun?
The Sun is an estimated 93 million miles away from our planet. Imagine riding in a car at a constant speed of 60 miles per hour. If we could drive that car directly to the Sun, with no traffic lights or pauses at fast food rest stops interfering, it would take us 177 years to reach the Sun from planet Earth.
(4) Our Sun looks so enormous in the morning and afternoon sky! How can it be smaller than the other stars we see at night?
Again, our star is an estimated 93 million miles from Earth. In distance, stars that we see in the night sky span much farther than that! Our next closest star, Proxima Centauri, is approximately 24.8 trillion miles away. Thus, the distance between Earth and the Sun and Earth and other stars is vast. The distances between us cause an optical illusion, making it appear as if our star is larger.
To accentuate this concept, conduct an experiment in your school, preferably in a long corridor. You will need four brightly colored paper plates (two 12 inch, two 9 inch, preferably yellow), and a camera. Select four students to stand at strategic distances along the corridor, approximately 12 equidistant feet behind one another. (Onlookers stand at the opposite end of the hall to observe and record their findings.) One child holding the 9-inch plate should stand at the starting point, closest to the onlookers. The second child holding the 12 inch plate stands at the 12-feet away; the next child holding the 9-inch plate, stands an additional 12 feet away, and the last with 12-inch plate in hand, stands at the last station. Have each child hold up his/her plates. Ask the onlookers to describe what they notice. Most will reply that the 9-inch plates appear larger than the 12-inch plate. Highlight that although the Sun is by no means equivalent to a paper plate, the overall concept depicted here helps one understand why our Sun appears to be so enormous in the morning sky. Take snapshots of the experiment in progress, so students will have a visual depiction of their observations for future reference.
(5) Is there gravity on the Sun, and if so, how does the Sun's gravity impact Earth and the remaining planets in our Solar System?
Yes, there is gravity on our Sun. Gravity is an invisible force that pulls us towards any object. That very same invisible force experienced on our planet exists on our Sun. The Sun's gravitational pull is so strong that it keeps the nine planets and other celestial bodies in our solar system in orbit.
(6) Is the Sun stationary?
Many people would wager that the Sun stands perfectly still. Remarkably, like the planets that orbit this celestial body, the Sun rotates on its axis in a counterclockwise-type motion, from west to east. Unlike the four terrestrial planets in our solar system, it rotates at different speeds from its north and south poles to its equatorial center.
(7) Is there a special term for the Sun's rotation?
The Sun's rotation is known as
. The rotation of the Sun varies at different points on its surface. It takes approximately 25 days for the sun to completely rotate near its equator. Near its north and south poles, the Sun rotates a bit slower. Scientists have noted it takes more than 30 days for rotation to occur near the Sun's poles. The fact that the Sun is gaseous allows deferential rotation. In fact, scientists are still attempting to understand why differential rotation occurs.
To help children get a better understanding of how the Sun rotates at different speeds, conduct this simple activity (which can be effectively coordinated with a physical educational session.) You will need hula-hoops and energized students raring to go. First have your students pretend they are the Sun. The hoops symbolize the gases rotating on the Sun's surface. Have the children begin swirling the hoops around their waste. Have them move at medium speed. They will observe that the hoop spins a bit faster than the movement initiated by their gyrating waists. Emphasize that although the human body and hula-hoops are by no means commensurate with the Sun, the activity gives an example of how different points can rotate at differing speeds.
(8) Does the Sun's rotation cause the Sun to disappear at nighttime?
The Sun does not literally disappear, and its rotation does not impact this occurrence. The illusion that it disappears is actually caused by the Earth's rotation in relation to the Sun. Although the Sun perpetually rotates, it remains in the very center of our solar system. Each of the nine planets revolves around the Sun. Our planet, Earth, rotates around its axis and revolves around the Sun. The rotation of our planet gives the illusion that our Sun has disappeared. When our side of the Earth is turned away from the Sun, we experience nighttime. When our side of the planet faces towards the Sun, it is daytime.
You will need a flashlight, two nametags marked "Connecticut" and "Beijing" respectively (any state or country on opposite sides of the world can be used), and a pair of students. Have one child pretend he/she is the Sun, the other planet Earth. The child representing Earth will have a nametag affixed to the front and back of his/her shirt indicating the two locales. Have the child holding the flashlight turn it on. The other child rotates slowly while remaining students observe. Ask your students to determine the time of day in each specified locale based on Earth's rotation.
(9) Like the nine planets, does the Sun also revolve?
Yes, our Sun revolves. Although it is in the center of our solar system, it revolves around the center of our galaxy, The Milky Way.
(10) Did scientists always believe the Sun was the center of our solar system around which the planets revolved? Who were the first scientists to believe the Earth revolves around the Sun?
Scholars state that in 150 A.D., a well-known Egyptian astronomer Ptolemy studied the movement of celestial bodies in his homeland, Alexandria. Based on his observations, Ptolemy conjectured that the Earth was a motionless mass at the center of the universe around which other heavenly bodies revolved.
Almost 1,400 years later, two scientists from other cultures countered Ptolemy's theory, setting in motion a new train of thought. In 1543, Polish astronomer, Nicolaus Copernicus, developed the theory that the Earth is a moving planet, and that it and other celestial bodies orbit the Sun. Copernicus did not scientifically prove his theory.
Approximately 50 years later, an Italian mathematician and explorer, Galileo Gallilei, agreed with Copernicus' view. Creating and using one of the first telescopes,
Galileo utilized scientific study to support his conviction.
During Galileo's time, most scientists and Christians agreed with Ptolemy's theory. Galileo, however, stood fast and continued his studies. Galileo suffered imprisonment because of his views and astronomical undertakings. Nevertheless, Galileo's research helped lay the foundation for our understanding of planets orbiting the Sun.
Shared reading and related writing assignment (see Section 2, Extending and Connecting – Lesson Plans).
(11) Where does the Sun disappear to on cloudy, rainy days?
The Sun does not disappear. It is still above us, hidden by thick clouds that cover the sky. If you were to travel on a jet, above those billowy stratus clouds, you would find our Sun shining brightly!
(12) How hot is our Sun?
That depends upon which part of the Sun we refer to. Our star generally is so hot that if you could land a PT Cruiser on its surface, that vehicle would sublimechange immediately from a solid into a gas! The Sun's core is an approximate 27 million degrees Fahrenheit. The Sun's photosphere is a few hundred miles thick. Circulated gas cools within this region, fluctuating from approximately 10,800 to 7,200 degrees Fahrenheit. That does not include temperatures found in the corona!
(13) Is the Sun solid, like a huge baseball?
Our Sun looks like a brightly lit, solid celestial sphere. In actuality, it is not solid at all. It is made up entirely of gas. If we were to try to stand on its surface, we would fall through it!
The Sun generally is divided into two major regions: the interior and the atmosphere. The interior consists of a very hot and dense core, where energy is generated. The remaining portion of the interior plays no role in energy generation, but energy generated in the core passes through these regions on the way to the atmosphere.
The solar atmosphere is usually divided into three parts: the photosphere, chromosphere, and corona.
(14) What are the attributes of these two regions?
The core is the interior portion of our Sun. Within the interior, nuclear fusion occurs and energy is generated. The core constitutes 30% of the Sun's interior. Gas is dense in this region, somewhat like flakes of snow packed tightly into a snowball. Unlike a snowball, the Sun's core remains gaseous at a whopping 27 million degrees Fahrenheit! The core is part of the radiative zone. The radiative zone comprises 70% of the Sun's interior. There is no bulk movement in this region. Nevertheless, energy in the form of photons travels very slowly through the radiative zone. Above the radiative zone lies the convection zone, where visual columns of gas transfer energy.
The Sun's atmosphere is comprised of three parts: the photosphere, often referred to as the Sun's surface, marks the beginning of the Sun's atmosphere. Within this area, gases circulate like boiling water in a saucepan. The bulk of this region is radiative. It is through the photosphere that our star's intense light and heat are emitted.
The chromosphere is the second layer of the sun's atmosphere. We cannot see it because bright light from the photosphere hides its light similarly to the way our Sun interferes with our ability to see other stars during daylight hours.
The outer portion of the Sun's atmosphere is the corona; the only time we can observe it is during a solar eclipse or through a special instrument called a coronagraph. The corona extends for millions of miles into space. The further the corona extends into space, the higher its temperature. Space scientists believe solar winds are generated in the corona, traveling throughout our solar system and beyond.
Related Activity/Resource: 3D Diagram and Sun Quiz
http://nmp.jpl.nasa.gov/st5/SCIENCE/sun.html This website provides a diagram of the Sun's layers, along with detailed information regarding each section. Provided by NASA, it can be downloaded and used free of charge. This engaging diagram can be enlarged and used during classroom discussion and as a resource tool near your word wall.
Students will create a 3D diagram, depicting the components of our Sun. Colored markers, assorted colored pliable clay, and a diagram master (reproduced on 8 ½ x 11 cardstock) are required. Download diagram from the student friendly website: Sun Printout/Coloring Page: EnchantedLearning.com Have your students fill in the designated spaces with clay. Put on additional accents using marker.
This fill-in questionnaire, accompanied by a scrambled image of the Sun, highlights 10 key facts about this celestial sphere. A perfect X-ray image of the Sun emerges if you answer all 10 correctly! Additional information concerning the Sun can be accessed here.
(15) What is nuclear fusion?
Nuclear fusion is a process where hydrogen gases combine to form helium in such a way that they release a tremendous amount of energy. Heat is continuously dispersed into surrounding areas in the form of hot plasma (a substance that consists of ions and electrons, that individually are not visible to the naked eye). All of this activity and movement causes temperatures to vary from the innermost to the outer regions of the Sun.
(16) Can you give a visual example of what goes on inside the convection zone?
To get a better feel for the process, think of an electric lava lamp. Clumps of wax are in the cylindrical glass portion of the lamp. When the lamp is turned on, heat melts the wax therein. The wax begins to float inside this container in an upward movement. When the melted wax reaches the top, it cools, and then falls back down to the base of the lamp.
The circulatory process continues. This is a visual example.
Bring in a lava lamp. Plug it in. Have students visually experience the process.
(17) The surface of our Sun looks smoothis it?
The surface of the Sun is very opaqueyou cannot see through it. If we were to take an up-close look at the Sun's surface, we would discover that it consists of individual blazing yellow blobs, each about the size of planet Earth. These objects called granules are actually convection cells in the Sun's outer layer. Because we are so far away from our star, we do not see these cells, but magnified with the use of scientific equipment, astronomers and astrophysicists know they are there!
(18) How does the photosphere produce heat energy?
The photosphere does not produce heat energy. It merely emits energy that has been transferred from the core.
(19) What is the hottest part of the Sun?
The hottest part of the Sun is its core or center. Envision the core as a gigantic nuclear furnace. The temperature there is approximately 27 million degrees Fahrenheit. Now that's hot!
(20) How hot is the corona?
The corona, the least dense region of the Sun's atmosphere, radiates thousands of miles from the Sun's photosphere. You can only see it during a total eclipse of the Sun or when you use specialized scientific equipment called a coronagraph. The corona extends millions of miles into outer space. The farther away from the Sun the corona extends, the hotter the temperature. Temperatures have been known to reach as high as 3.6 million degrees!
(21) Why does the Sun's temperature differ from its inner core to its outer surface?
Again, nuclear fusion occurs in the core, resulting in that phenomenal temperatureapproximately 27 million degrees Fahrenheit! Energy in the form of heat and light is produced by nuclear fusion. Energy produced in the Sun's core enters the radiative zone. Energy is radiated from this area to surrounding plasma. Photons spread out. These photons come to the inner edge of the convection zone. Here, hot air rises and cool air descends. The convection process continues. From the inner edge to the outer edge of the convection zone, energy cools. By the time it reaches the photosphere, the temperature is approximately 10,800 Fahrenheit.
(22) Is there temperature variation in the Sun's photosphere as well, and if so, why?
Yes, there is temperature variation in the Sun's photosphere. In the photosphere, gas cools from about 10,800 degrees to 7,200 degrees Fahrenheit. This variation occurs because the photosphere is a few hundred miles thick. Through the photosphere, the Sun's intense heat and light is given off. It passes through the atmosphere's outer layers and then into space.
(23) What are photons, where do they begin, and how do they travel?
Photons are particles of light. Within the Sun's core, they move very slowly. This is because the Sun's core is very dense. Photons move so slowly within the Sun's core that it takes approximately 170,000 years for them to travel and finally escape to the solar surface as sunlight. When photons escape the core and enter the photosphere, they begin to travel at a much faster rate. Amazingly, solar energy that reaches us takes only 8 minutes to travel from the photosphere.
To visualize the movement of photons within the Sun's core, find a place where floating dust particulars are very visible. Explain that because of the Sun's density, photons move very slowly. They bump into gas molecules just like particles of dust we see in the air. Notice that they never go straight, but seem to bump into each other. Photons move in a similar fashion. Within the core, they never travel in a straight direction.
(24) How long does it take the sun's rays to reach Earth?
The Sun's energy reaches Earth in the form of electromagnetic radiation. The Sun's rays (electromagnetic radiation) travel in straight lines. Note that the Sun's light and heat cannot reach us by conduction or convection because space is almost completely empty, i.e., it is in a vacuum, and there is nothing to transfer the energy from the Sun to the earth.
It takes approximately eight minutes and 20 seconds for the Sun's light waves to travel all the way to our planet from the surface of the Sun.
(25) What are solar winds, and do they blow hot air?
The term "solar winds" does make one envision blustery hot air gusting across the earth. Solar winds, however, have nothing to do with gusting air. They are actually tiny particles of small ions that carry electricity (plasma) emanating from the Sun's corona that moves all around. Plasma is affected by the electric and magnetic fields resulting from the extremely hot temperatures from the Sun. These "winds" or fields travel in all directions from 185 to 435 miles an hour. When they travel far away from the Sun, far into outer space, they pick up speed. Solar winds travel so far, they reach our planet and beyond.
(26) Do solar winds affect our planet in any way?
Yes they dodramatically! (They also affect other parts of our solar system.) Solar winds carry magnetic fields. These magnetic fields interact with the Earth's magnetic field. On planet Earth, solar winds contribute to the creation of aurorea (northern and southern lights). These are visible effects of solar winds.
Aurorae are beautiful, colorful displays of light caused by the interaction of solar wind and our planet's magnetic field. Aurorae occur because plasma (electrically charged atoms and electrons energized by extremely high temperatures) is drawn toward the Earth's northern and southern magnetic poles. As plasma nears and reaches the Earth, ions drawn toward Earth's northern and southern magnetic poles result in surrounding areas in Earth's atmosphere to glow. We see that glow in the form of beautiful displays of colorful light. Aurorea are experienced in Alaska, near the North and South poles, and even as near as New Hampshire.
Additionally, near Earth, solar winds move at an extremely rapid speed, as much as 1 million miles per second! The Earth also has a magnetic field. At times, the solar winds are exceptionally strong. When they reach the Earth's atmosphere, they sometimes cause damage to space satellites and other scientific equipment orbiting our planet. They interfere with radioeven cell phone transmissions!
(27) What are solar flares and plages and where are they found?
Solar flares are temporary outbursts of energy (gamma rays [high energy]; light, x-rays, ultraviolet, visible, infra-red [which we feel as heat], microwave, radio, and energetic particles) that extend from the outer edge of the chromosphere into the corona and beyond. Plages are bright patches that are hotter than their surroundings on the Sun's surface. Solar flares and plages are visible only with specialized scientific equipment called a spectrohelioscope.
This website provides a birds-eye view of the spectrohelioscope along with other space equipment used to study our Sun and other celestial bodies.
(28) What are sunspots and where are they located?
Sunspots are found on the Sun's photosphere. They look like dark blemishes on this glowing mass. They are caused by magnetic fields within the Sun. Here, the Sun's magnetic field is extremely intense. Sunspots are dark in color because their temperature is low as compared to the surrounding photosphere. The dark brownish center is called the umbra. A light brownish region called the penumbra surrounds it. Their temperatures range between 8,250 and 9,500 degrees Fahrenheit.
This is an interactive website to chart and experience the recording of sunspots moving along the Earth's surface. Students will record and graph information for a two-week duration using this simulated image.
(29) What are prominences, and where are they located?
Prominences can be described as balls of flaming, hot gases that bubble and spin on the Sun's surface (photosphere). They often shoot out from the Sun's surface like long wiry arms. Technically speaking, they are high-density clouds of gas projecting outward into space. They can be over 100,000 miles long. They can retain their shape for several months at a time before dissipating.
(30) Some stars are blue or white. Some like our Sun are yellow. Some are red. Why do they differ in color?
The surface temperature of stars causes their color: if the temperature of a star is above 54,000 degrees Fahrenheit, that star takes on a blue violet appearance. When its temperature falls between 13,000 to 20,000 degrees Fahrenheit, the star is white. Between 9,000 and 11,000 degrees, the star is yellow. Between 2,300 and 9,000 degrees Fahrenheit, it is yellowish orange or orange in appearance, and less than 2,300 Fahrenheit, the star is red.
(31) Some days, the Sun appears to be reddish orange in color. Why does this occur?
The reddish orange appearance of our Sun is caused by pollution, specifically dust in Earth's atmosphere. Dust scatters light. Blue and violet light are easily scattered; red is not. Thus, when the sky is very cloudy, we are apt to see an orangey red colored Sun. The Sun itself has not changed colors; it is still yellow.
32) How do scientists know so much about our Sun?
Since 1955, many space probes and scientific equipment have been launched to study our Sun. Specialized instruments are used to measure solar winds, solar flares, cosmic rays, and the Sun's magnetic field. High-powered telescopes and cameras are used to take photos of the Sun. The Solar and Heliospheric Observatory (SOHO), launched in 1955, collects information about solar winds that surround the Sun and extend throughout the solar system. In 1965, 13 space probes were sent constituting the U.S. Pioneer Series. This scientific equipment records and transmits data to National Aeronautics and Space Administration (NASA) scientists. In 1973, The U.S. Skylab space station was used to observe our star. The Ulysses space probe was launched in 1990. It studies activity that occurs at the Sun's north and south poles and the space above and below these areas. YOH KOH, a space probe sent to study the Sun, was sent into space in 1991. A joint mission conducted by the United States, Britain, and Japan, it studies high-energy radiation from solar flares. Today, the study of our Sun using sophisticated technology continues on a worldwide basis.