Lesson 1 | The View from Earthimages.pcmac.org/SiSFiles/Schools/AL/MobileCounty/HankinsMiddle/Uploads/Documents...MiniLab LESSON 1: 20 minutes 1. Read and complete a lab safety form.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
How can you “see” invisible energy? You see because of the Sun’s light. You feel the heat of the Sun’s energy. The Sun produces other kinds of energy that you can’t directly see or feel.
Procedure
Launch Lab LESSON 1: 20 minutes
Data and Observations
Think About This 1. How did the light from the different light sources affect the color of the beads?
2. What do you think made the beads change color?
3. Key Concept How do you think invisible forms of light help scientists understand stars and other objects in the sky?
1. Read and complete a lab safety form.
2. Put 5–6 beads into a clear container. Observe the color of the beads.
3. In a darkened room, shine light from a flashlight onto the beads for several seconds. Record your observations in the Data and Observations section
below. Repeat this step, exposing the beads to light from an incandescent lightbulb and a fluorescent light. Record your observations.
4. Stand outside in a shady spot for several seconds. Then expose the beads to direct sunlight. Record your observations.
How does light differ? Light from the Sun is different from light from a lightbulb. How do the light sources differ?
Procedure
MiniLab LESSON 1: 20 minutes
1. Read and complete a lab safety form.
2. Follow instructions included with your spectroscope. Use it to observe various light sources around the classroom. Then use it to look at a bright part of the sky.
Do not look directly at the Sun.
3. Use colored pencils to draw what you see for each type of light in the Data and Observations section below.
Data and Observations
Analyze and Conclude 1. Compare and Contrast What colors did you see for each light source? How did the
colors differ?
2. Key Concept How might a spectroscope be used to learn about stars?
Use Proportions A rate is a ratio of two units. For instance, a car that travels 65 miles in 1 hour is moving at a rate of 65 mi/hr or 65 mi _____
1 hr .
Two equal ratios can be written as a proportion. If one of the numbers in a proportion is unknown, you can cross multiply to solve for the unknown number, x. When writing a proportion, make sure you put the numbers in the correct places. The numerators of the ratios should have the same units, and the denominators of the ratios should have the other units.
If light travels around 10 trillion km in 1 year, how long would it take light to reach Earth from a star that is 280 trillion km away?
Step 1 Use the information in the problem to write a proportion. The numerator of each fraction has kilometers as units, so the proportion is written correctly as
10 trillion km ____________ 1 y = 280 trillion km _____________ x .
Step 2 Cross multiply.
10 trillion km (x) = 280 trillion km y
Step 3 Solve for x by dividing both sides.
10 trillion km (x) ______________
10 trillion km =
280 trillion km y ______________
10 trillion km
x = 28 y
Practice
Math Skills LESSON 1
1. If light travels around 10 trillion km in 1 year, how long would it take light to reach Earth from a star that is 390 trillion km away?
2. The star Proxima Centauri is 4.2 light-years away from Earth. How many kilometers separate this star from Earth?
3. An astronomical unit (AU) is about 150 million km. If Jupiter is 5.2 AU from the Sun, then how many kilometers away from Jupiter is the Sun?
4. If light travels about 300,000 km/s and Earth is about 150,000,000 km from the Sun, how many seconds does it take light from the Sun to reach Earth?
The View from EarthIn this activity, you will investigate how distance affects brightness. You will need two flashlights (one large and one small), a darkened room, and a learning partner. Note: The lightbulbs in your flashlights should be the same type—high intensity or incandescent.
1. With your partner, place the large flashlight on the floor at one end of a large room. The flashlight should be perpendicular to the wall so it shines into the room. Turn the flashlight on.
2. Place the small flashlight on the floor in the center of the room. Make sure this flashlight is pointing in the same direction as the large flashlight. Turn the flashlight on.
3. Darken the room and observe the flashlights. Be careful as you move around the darkened room.
4. Your partner and you should view both flashlights head on. Explain which light is brighter and why.
5. Now work with your partner to vary the distances of the flashlights from your observation spot so both appear equally bright.
6. Explain why both flashlights look equally bright, although one is actually brighter than the other.
7. Discuss your observations with your partner. Explain the outcome of step 5 in terms of absolute and apparent magnitude.
The View from EarthKey Concept What can astronomers learn about stars from their light?
Directions: On each line, write the term from the word bank that correctly completes each sentence. Some terms may by used more than once or not at all. Use the diagram to answer questions 8 and 9.
Electromagnetic SpectrumLow energy High energyLong wavelength Short wavelength
Radiation Type Radio Microwave Infrared Visible Ultraviolet X-ray Gamma ray
The View from EarthKey Concept How do scientists measure the distance and the brightness of objects in the sky?
Directions: On the line before each statement, write T if the statement is true or F if the statement is false. If the statement is false, change the underlined word(s) to make it true. Write your changes on the lines provided.
1. Spectroscope is the apparent change in an object’s position caused by looking
at it from two different points.
2. Astronomers use parallax to measure how far some objects are from Earth.
3. Astronomical units describe distance outside the solar system.
4. One AU is the average distance from Earth to the Moon.
5. Mercury and Venus are less than 1 AU from the Sun.
6. Mars and Jupiter are more than 1 AU from the Sun.
7. One light-year is the distance the Sun travels in 1 year.
8. A light-year measures time.
9. The nearest star to the Sun is about 4.2 kilometers away.
10. It would take 10 years for light to reach Earth from a star that is 100 trillion km
away.
11. The distant stars you see today appear as they will be in the future.
The View from EarthKey Concept How do scientists measure the distance and the brightness of objects in the sky?
Directions: Decide whether each statement refers to apparent magnitude, absolute magnitude, or both. Complete the Venn diagram by writing the number of each statement in the correct section. Each statement is used only once.
1. Luminosity is the true brightness of an object. It is the amount of energy a body radiates per unit of time.
2. Astronomers can measure how bright stars are.
3. The Sun is the brightest object in the sky.
4. depends on a star’s temperature and size, not its distance from Earth
5. does not describe a star’s actual brightness
6. The brightness of a star is described using a scale with positive and negative numbers.
7. On a star magnitude scale, stars with higher numbers are less bright.
8. can be calculated from a star’s distance and apparent magnitude
9. depends on a star’s distance from Earth
10. originally described by the Greek astronomer Hipparchus
11. The lower a star’s absolute magnitude is, the higher its luminosity will be.
Before Europeans developed navigational instruments that would allow them to venture into the open ocean, their travels by ship were limited to sailing close to the coastlines of continents. However, before the common era , voyagers from Fiji, Tonga, and Samoa were able to navigate without instruments and settled islands in an ocean area of more than 10 million square miles.
The Polynesians and the Stars Polynesian navigators used the rising
and setting points of celestial bodies to find directions. During the day, the Sun gave directional points, rising in the east, and setting in the west. At night, navigators held their course by orienting their canoes to the rising and setting points of stars on the eastern and western horizons. They also used pointer stars and the meridian. The meridian is an imaginary line that is perpendicular to the horizon; pairs of stars that cross the meridian at the same time point north and south.
The Regiment of the North Christopher Columbus observed the sky
to keep time. Columbus understood the Sun’s path through the sky. The Sun and the stars move 15 degrees each hour from rising to setting.
All navigators of this period used the Regiment of the North to keep track of elapsed time. To visualize this system, draw a person inside a circle, with the head at the top, feet at the bottom, and each arm stretched with fingers pointing to the 3 o’clock and 9 o’clock positions. Draw the North Star above the person’s head and lines through the person, with 45-degree angles between them. (Draw a vertical and horizontal line bisecting the circle. Add two diagonal lines, each one bisecting two of the quarter-circles. There should be 8 equal parts, each with a 45-degree angle.)
The two brightest, outermost stars of the Little Dipper, called the Guards, move 15 degrees every hour as they revolve counterclockwise. If the Guards move from the person’s head to foot, they have moved 180 degrees, or 4 lines, or 12 hours. If the stars moved 3 lines, then 9 hours had passed.
On Sept. 30, 1492, Columbus wrote in his log: “…the Guards are slightly below the arm on the west at night but at daybreak appear below the arm to the east. If this observation is correct, it appears that I only proceeded three lines last night, or nine astronomical hours.”
Applying Critical-Thinking SkillsDirections: Answer each question or respond to each statement.
1. Describe In relation to the front, back, right, and left sides of your body, which directions would you point your canoe if you wanted to go (a) north, (b) south, (c) east, and (d) west when the Sun is rising to your right? Explain your answers.
2. Calculate Using the Regiment of the North, how much time has elapsed when the Guards have moved from the head to halfway between the hand and the foot on the west? Explain how you got your answer.
Where is the Sun? Early civilizations used the Sun’s movements to tell the time of day and anticipate the
change of seasons.
Observe the Sun’s MovementNever look directly at the Sun! Even looking at the Sun with dark sunglasses or through
a dark filter can damage your eyes. In this activity, you will observe indirectly the movement of the Sun in the sky. Begin
early on a sunny day and plan to make periodic measurements throughout the day.
1. You will need a 2 ' by 3' piece of heavy paper or a large, flat sheet of cardboard; a large container of soil or stone; a meterstick (or a tall, heavy object such as a glass bottle); a marker; and a compass.
2. Find an outdoor space that is not occupied or shaded throughout the day.
3. At your spot, determine which direction is north. Place the cardboard or heavy paper on level ground with the top edge facing north. Mark the directions east, west, and south on the paper and arrange it so it does not move. Place the meterstick upright in the container and put it at the center of the southern edge of the paper.
4. On the paper, mark the line and the tip of the shadow that is cast by the meterstick with a marker and record the time of the observation.
5. Every hour during the course of the day (or 9:30 A.M., noon, and 2:30 P.M. if you can’t do it every hour), record the movement of the shadow of the meterstick by marking the line and top of the shadow. Each time you mark the meterstick’s shadow, also note the time on the paper.
6. On a fresh sheet of paper, draw a diagram of the times and lengths of the shadows you recorded. Explain how the shadows changed in size and direction over the course of the day.
7. Imagine you are a member of an early civilization that has no technology to keep time. You have noticed how the shadows change as the Sun moves across the sky. Invent a way to tell the approximate time of day. To start, decide what you would use as a unit of time.
How can you use scientific illustrations to locate constellations? You might have heard that stars in the Big Dipper point to Polaris. The Big Dipper is a small star pattern in the larger constellation of Ursa Major. Ursa Major means “big bear” in Latin. It is the third-largest of the 88 modern constellations in the sky. Study the image of Ursa Major. Can you find the seven stars that form the Big Dipper? You can use a star finder to locate stars on any clear night of the year. The star finder also helps you see how constellations move across the sky.
Materialsstar finder
Learn It Scientific illustrations can help you understand difficult or complicated subjects. Interpret scientific illustrations on the star finder to learn about the night sky.
Try It 1. Read and complete a lab safety form.
2. Read the user information provided with the star finder.
3. Rotate the wheel until the star finder is set to the day and time when you will be viewing the night sky. Observe how the ancient constellations marked on the star finder move.
4. Make a list of the bright stars, constellations, and planets you might be able to see in the sky.
5. Use the star finder outdoors on a clear night. As you hold the star finder overhead, be sure the arrows are pointing in the correct directions.
Apply It 6. What ancient constellations, planets, and stars were you able to see?
7. Did you locate Polaris? Why will you be able to see Polaris 6 months from now?
Interpret Scientific Illustrations Skill Practice LESSON 1: 30 minutes