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Module 18 Stars - See content
Secondary education (bio sci)
Eastern Visayas State University
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Module 18
Beyond the Solar System
What this module is about
This module presents information on some of the deep-sky objects we love to see in the night sky, the stars. The activities presented here are designed to stimulate your interest to explore these jewels of the night sky. Come with me and have fun learning the following lessons:
Lesson 1 - The Glittering Star Lesson 2 - The Star Sign
What you are expected to learn
After going through this module you should be able to:
- explain the distance of stars from Earth in terms of appropriate units;
- explain the life cycle of a star; and
- construct a constellation.
How to learn from this module
I know you are excited to learn the lessons just as I am but remember these tips to help you achieve the objectives of this self-learning kit.
- Read instructions carefully.
- Follow instructions carefully.
- Answer the pretest before you start the lesson.
- Observe the time limit to finish the module.
- Take note and record points for clarifications.
- Try to achieve at least a 75% level of proficiency in the tests.
- Work diligently and honestly.
- Answer the posttest honestly.
___7. Most astronomers agree that the stars are born within huge clouds of dust and gases called a. sun b. pulsars c. auroras d. nebulae
___8. The actual amount of light or brightness given off by a star is called a. parallel shift b. apparent magnitude c. absolute magnitude d. none of the above
___9. Most of the core of a red giant is made of a. iron b. helium c. methane d. hydrogen
___10. Which of the following units is used in measuring the distance of a star from the earth? a. mile b. inch c. kilometer d. light year
___11. Which of the following statements is true? a. The higher the magnitude number, the brighter the star b. The lower the magnitude number, the dimmer the star c. The lower the magnitude number, the brighter the star d. All statements are true
___12. Which of the following is the correct speed of light? a. 300,000 kilometers b. 9,460,800,000,000 kilometers c. 300,000 kilometers per second d. 9,460,800,000,000 kilometers per second
___13. What determines the fate of a dying star? a. its mass b. its size c. its color d. its temperature
Key to answers on page 20
___14. Which of the following describes the constellation Ursa Major? a. lion b. fish c. dragon d. big bear
___15. Which of the following best describes a black hole? a. a place where angels meet b. the darkest and coolest place in space c. the outermost boundary of the universe d. a region in space where light cannot escape
Lesson 1 The Glittering Star
Twinkle twinkle, little star, How I wonder what you are! Up above the world so high, Like a diamond in the sky.
Tis your bright and tiny spark, Lights the trav’ller in the dark: Tho’ I know not what you are Twinkle, twinkle, little star.
When was the last time you’ve recited this poem? Though little is known about these glittering objects in the sky, that has not stopped poets and writers from writing beautiful poems and stories about these deep-sky objects.
What is a star?
A star is an enormous glowing ball of hot gas. There are billions of stars contained in the galaxies of the universe. The Milky Way is the galaxy where our solar system belongs. All the individual stars you see in the night sky are members of our galaxy.
escape. According to studies made, a black hole swallows any matter or energy that comes near it.
Why do stars twinkle?
Do you know that stars do not twinkle? They seem to twinkle when we see them from the earth’s surface. The light of the stars is bent or refracted as it travels through the thick layers of the earth’s atmosphere. This bending of light results in the twinkling of the stars.
Why do you not see stars in the daytime?
Think twice! During daytime we cannot see any star other than the Sun. Yes, our own sun is a star. This is the nearest and brightest star to earth. This is the only star we can see during the day. As the Sun lits up the sky, more light is coming from the sky than from the stars. But though you can’t see other stars during the day, it does not mean they are not there.
Other than the sun, what star is nearest to earth?
Other than the sun, the Proxima Centauri is the nearest star to earth. It is 4 light years away from earth. A light year is the standard unit of distance for deep sky objects. It is the distance light travels in a year, or about 10 trillion kilometers.
To give you an idea of how far Proxima Centauri is, let us say you will go there with a speed of 300, 000 kilometers per second, which is the speed of light. At this speed, it will take you more than 4 years and 3 months to reach the place.
Listed below are some stars with their distances from earth.
Star Name Distance from earth Sirius 8 light years Vega 26 light years Betelguese 300 light years Deneb 400 light years Rigel 540 light years
How bright are the stars?
Star brightness is described in terms of magnitude. The brightness of a star as seen from earth is called apparent magnitude , while its true brightness is called absolute magnitude. The magnitude sequence for stars starting with the brightest is ... -2, -1, 1, 0,1, 2, 3, 4, 5, 6, 7, magnitude... The brightest stars have the largest negative numbers. Dimmer stars are positive numbers. For
example, a star of magnitude 1 is brighter than a star of magnitude 2. While a star of magnitude -2 is brighter than a star of magnitude -1.
The table below shows the magnitude of some stars.
Star Name Magnitude Sirius -1. Vega -0. Rigel 0. Betelguese 0. Deneb 1.
Do you know the color of the stars?
Looking at the sky on a clear night, you might notice that stars have different colors. Some stars look red, while most look whitish or bluish. You may use binoculars to see the colors more clearly.
What does the color of the stars tell us?
Did you know that the color of the star indicates its temperature? Astronomers can determine the surface temperature of a star by measuring its color. They use different methods in determining the temperature of stars. One method is the use of an instrument called photometer. A photometer consists of three filters that transmit light in three different wavelength ranges. Then the scientists compare the two neighboring wavelength bands to determine which is brighter and they convert the color relationships to temperature. Blue stars are hotter than red stars. Rigel is an example of a bright blue star while Betelguese is a bright red star.
How hot is a star?
Always remember that the temperature of a star depends on its original mass when it was formed. In general, the more massive a star is, the hotter its surface. Stars have temperatures between about 2,600 degrees Kelvin and 50,000 degrees Kelvin. Our sun has a surface temperature of 5,780 degrees Kelvin. One of the most important tools of astronomers is the Hertzsprung-Russel diagram or simply called H-R diagram. It was developed by a Danish astronomer Ejnar Hertzsprung and an American astronomer Henry Norris Russel. The H-R diagram is a plot of different stars indicating their brightness versus their temperatures.
Large star. A celestial mammoth that releases up to 10 million times the power of the sun
Orion Nebula surrounded by disk of dust and gas ______
Betelguese star. A red supergiant. ______
Embryonic star accumulates more mass from the surrounding.
Crab Nebula the remains of an exploding star. ______
Supernova blast. _____
Nova Cygni ballooning bubble of gas blasted off a star. _____
Question: What was your basis of classifying the pictures (persons and stars) by age? Explain the life cycle of a star.
SOURCE: btc.montana/ceres/html/LifeCycle/images/M16Eagle
What you will do Activity 1 Glittering Stars
This craft makes a beautiful picture of a night sky. The stars in our galaxy are represented by the glitter (or sand).
Materials needed:
black construction paper pencil or white crayon glue glitter (or sand) old newspapers to work on
Procedure:
A. Work on some old newspaper. On the black construction paper, using a pencil or crayon, draw some sketches of your own stars. Some are big and some are small. Some stars are scattered throughout the construction paper, and some are clustered. The black background represents the night sky.
B. Put glue along the lines of your stars.
C. Sprinkle glitter (or sand) on each star. You may use different colors of glitters for each star. Tilt the paper onto some newspaper to shake off the loose glitter (or sand).
What you will do Activity 1.
How fast is light?
- Scientists use a unit called light year to measure really long distances. Light travels at 186,000 miles per second (300,000 kilometers per second), therefore, a light second is 186,000 miles (300,000 kilometers). A light year is the distance that light can travel in a year. Calculate the exact number of miles in a light-year?
Why would people want to invent constellations?
Constellations were created to help our ancestors, even astronomers, remember stars. Long time ago, farmers used them as markers for seasons. When certain constellations appear in the sky, they would know when to begin planting or reaping.
Are you excited now to have another stargazing session? I’m sure you are! But before you go, as a beginner you have to bring with you a star map or sky map. The sky map shows the entire sky as viewed from a given location at a specified time and date. The sky map will tell you which of the constellations are visible to you at this time of year. But remember that constellations in the sky are not exactly the same as the constellations in your star map. You may ask your teacher where to get a copy of a sky map for the specific time and date you want. I’m sure she is willing to help!
The Big Dipper or the Great Bear is one of the most well known star groups. Actually, the Big Dipper is not really a constellation, but an asterism. An asterism is a more recognizable part of a larger constellation. The Big Dipper is a part of Ursa major constellation.
Most of the constellations are visible to the naked eye under good weather conditions. However, if you are living in the city, the brightness of city light may not allow you to see all the stars. The use of binoculars will make the stars look more impressive.
Once you have with you a copy of a sky map, with or without binoculars, you can now look for a good stargazing place. The city is still a good place to view the sky. Since only the brighter stars can be seen, you will be able to find the constellations easily.
If you think you are having difficulty searching for star patterns then concentrate on the circumpolar stars because they are always above the horizon. They are called circumpolar because they appear to circle the north celestial pole every night. Take a look at these circumpolar stars.
Figure .21 The Circumpolar Stars
Cepheus
Draco Ursa Minor
Camelopardis
Cassiopeia
Ursa Major Lynx
What you will do
Connect the stars following the number sequence then name the constellation.
A. (The Queen) ________________ B. (The Little Bear)______________ - Key to answers on page
- Self-Test 2.
- C. (The king) ________________ D. (Draco) ________________________
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Let’s summarize
What are the things that you have learned from this module?
- Scientists believe that all stars came from huge clouds of gas and dust called nebulae.
- The nuclear fusion is the reaction that converts hydrogen atoms into helium atoms releasing a tremendous amount of heat, causing the star to glow.
- A protostar is a very young star. It becomes a true star when nuclear fusion starts.
- The star is considered old when it has reached the red giant phase that eventually explodes and turns into a dim, cool object.
- The explosion of a massive star is called supernova.
- The destiny of a star depends on how massive it is. It may become a white dwarf, a neutron star, or a black hole.
- The color of the star indicates its surface temperature. Blue is the color of the hottest star.
- A light year is the standard unit of distance for deep sky objects like stars. One light year is equal to 9,460,800,000,000 kilometers away from the earth. Other than the sun, Proxima Centauri is the nearest to earth.
Posttest
Multiple Choice: Write the letter of the best answer before each number.
Multiple Choice: Write the letter of the best answer on the space provided.
- What color is the hottest star? a. red b. blue c. white d. yellow
Key to answers on page 21
Which of the following statements is true? a. The higher the magnitude number, the brighter the star. b. The lower the magnitude number, the dimmer the star. c. The lower the magnitude number, the brighter the star. d. All statements are true.
Most of the core of a red giant is made of a. iron b. helium c. methane d. hydrogen
What determines the fate of a dying star? a. Its mass b. Its size c. Its color d. its temperature
Which of the following units is used in measuring the distance of a star from the Earth? a. mile b. inch c. kilometer d. light year
Which of the following best describes a black hole? a. a place where angels meet b. the darkest and coolest place in space c. the outermost boundary of the universe d. a region in space where light cannot escape
The star is considered old when a. all its fuel is gone b. it becomes black hole c. it has reached the giant phase d. it has reached the protostar phase
Which of the following describes the constellation Ursa Major? a. lion b. fish c. dragon d. big bear
Key to Answers
Pretest
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Activity 1 How old are they?
(Part 1) Rank 2, 4, 1, 3, 5 (Part 2) Rank 3, 1, 4, 2, 7, 6, 5
The persons’ age can be identified just by looking at persons’ size and appearance. The age of the stars in the pictures can also be classified based on their sizes and general appearance. The descriptions and activities of each star are given to help you in classifying.
Activity 1 Students are free to do their own stars.
Activity 1 How fast is light
- A light year is 5,865,696,000,000 miles (9,460,800,000,000 kilometers). That's a long way! (186,000 miles/second * 60 seconds/minute * 60 minutes/hour * 24 hours/day * 365 days/year = 5,865,696,000,000 miles/year)
- It would take 8 years and 6 months to reach Sirius! (1 light year is 9,460,800,000,000 kilometers * 8 = 81,362,880,000,000 kilometers. Use the formula time=distance/speed then, 81,362,880,000,000 kms/ 300,000 kilometers per second = 27,120,960,000, seconds. Convert 27,120,960,000,000 seconds to hour, then to a day then to a year. The answer is 8 years and 6 months.
Module 18 Stars - See content
Course: Secondary education (bio sci)
University: Eastern Visayas State University
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