1. 1. A. Choose the letter of the best answer. For numbers 1 to 3, use the table below that presents information about stars A, B, C, and D. Star Color A Red B Yellow C White D Blue
2. 2. 1. Which star is the hottest? a. A b. B c. C d. D 2. Which star is very similar to our sun? a. A b. B c. C d. D
3. 3. 3. How do stars appear to move in the night sky? a. From East to West b. From North to South c. From East to West d. From South to North
4. 4. 4. Stars appear to move in the sky because a. The Earth is rotating on its axis. b. The universe is expanding. c. The night sky is rotating. d. New galaxies are formed.
5. 5. 5. If you are located at the North Pole, where will you see the Polaris? a. Overhead b. Just above the horizon c. Around 45 from the horizon d. Polaris will not be seen in the North Pole
6. 6. 6. Which constellation is prominently seen in the sky during summer? a. Orion b. Pegasus c. Hercules d. Virgo
7. 7. 7. Based on apparent magnitude, which of the following stars is the brightest? a. Alpha centauri b. Betelgeuse c. Rigel d. Sirius
8. 8. 8. Why do stars have colors? a. It is because of the presence of oxygen. b. It is because of the presence of carbon dioxide. c. It is because of varied temperatures. d. It is because of the different locations.
9. 9. 9. Stars can be found in large groups throughout the universe. What are these groups called? a. Solar system b. Comets c. Constellations d. Asteroids
10. 10. 10. The star Algol is estimated to be as bright as the star Aldebaran and have approximately the same temperature as the star Rigel. Which of the following statement is correct? a. Algol and Rigel have same color. b. Algol and Rigel have the same brightness. c. Allgol and Aldebaran have the same in size. d. Algol and Rigel have the same brightness and color.
11. 11. Rigel Sirius
12. 12. Definition of terms: Star is a swirling, glowing ball of gases. Constellation is a group of stars that has a shape resembling that of an animal, a mythological character, or some other object. Galaxy is a large constellation or large groups of gases, dust and stars in space held together by gravity. Type: Elliptical galaxy, spiral galaxy and irregular galaxy.
13. 13. When we look at the night sky, we see thousands of stars. In reality, there are approximately 400 billion stars in our galaxy, and there are about 170 billion galaxies. A person can see only about 3,000 stars on the average.
14. 14. Characteristics of Stars Color and Temperature Brightness and Magnitude of Stars Sizes of Stars Distances of Stars Composition of Stars
15. 15. Characteristics of Stars Color & Temperature - Star color ranges from red to blue. The color of the star indicates its surface temperature. - The coolest star is about 2800C at the surface. These star appear red. The temperature of the hottest star is about 28 000C or higher. These star appear blue.
16. 16. Sun Yellowish, 5500C Stars that are cooler appear orange, stars that are hotter than the sun appear white.
17. 17. Table 1. Color and Temperature of Selected Stars Star Color Surface Temperature in Celsius Sun Yellow 5,700 Proxima Cantuari Red 2,300 Epsilon Iridani Orange 4,600 Vega White 9,900 Sirius White 10,000 Alnilam Blue 27,000
18. 18. Figure 2 shows the size of the Sun, the closest star to Earth, as compared to some other stars that we see at night. As we can see, the Sun is so small compared to other nearby stars. Also, Sirius, which appear bigger than Rigel, is actually very small compared to Rigel. It appears larger only because it is closer to us.
19. 19. Characteristic of Star Brightness - The brightness of a star as seen from the Earth depends on two factors: distance and the actual brightness (or absolute brightness) of the star. The stars brightness as seen from Earth is its apparent brightness, apparent brightness depends on how far away a star is from the Earth.
20. 20. Astronomers consider the stars absolute brightness when comparing stars. A stars absolute brightness is the brightness the star would have if all stars were the same standard distance from Earth.
21. 21. Characteristics of Stars Sizes of Stars - Stars varies in size, from huge to supergiants to tiny neutron stars. - Astronomers group stars in to five types: neutron stars, white dwarfs, medium- sized stars, giants and supergiants.
22. 22. Neutron stars are the smallest, it has a diameter of about 16 km. White dwarf is about 7300 km, slightly greater than that of the Earth. Medium-sized star is about one-tenth the diameter of the sun. Sun has 1.35 million km in diameter. Giant star is 10 to 100 times that of the sun. Supergiant stars is up to 1000 times the diameter of the sun.
23. 23. Characteristics of Stars Distances of Stars - Scientist use parallax to determine how far away a star is from Earth. A parallax is an apparent change in the position of an object caused by a change in the position of the observer. - The closer a star is to Earth, the greater its apparent change of position. Very distant stars seem not to shift position at all.
24. 24. Scientists express distances between stars in light years. A light year is the distance that light travels in one year at a speed of 300 000 km per second (kps). A light year is about 9.5 trillion km or 9 500 000 000 000 km. The closest star is Proxima Centauri, 4.2 light years from Earth. Other stars are hundred of light years away.
25. 25. Characteristics of Stars Composition of Stars - Using spectroscope, astronomers have found that almost all stars have the same general chemical make-up. The most element in stars is hydrogen, the lightest element that makes up 60% to 80% of the total mass of a star. The second element is helium, combination of H and He make up about 96% to 99% of stars mass. - Other elements are oxygen, neon, carbon and nitrogen.
26. 26. The Polaris Polaris, commonly known as North Star, is the brightest star in the constellation Ursa Minor (Little Dipper). It is very close to the north celestial pole, making it the current northern pole star. Because it lies nearly in a direct line with the axis of the Earth's rotation "above" the North Pole, Polaris stands almost motionless in the sky, and all the stars of the Northern sky appear to rotate around it. In Figure 3, Polaris and the star trail are seen. Star trail is a type of photograph that utilizes long-exposure times to capture the apparent motion of stars in the night sky due to the rotation of the Earth.
27. 27. Fig. 3 Polaris and the Star Trail over Mt. Pulag
28. 28. In Metro Manila, when you face North, Polaris, which is 11.3 from the horizon, is seen at around 15 due to atmospheric refraction. In some parts of the country (i.e. Southern Philippines), it would be very difficult to locate Polaris since star lights near the horizon are washed out by lights lit by men, and /or obstructed by man- made or topographical structures and/or trees.
29. 29. Fig. 4 Polaris as viewed from the Philippines (Quezon City). To locate Polaris, face North and locate the Big Dipper. Two stars (Merak & Dubhe) in the Big Dipper are called pointer stars because they seem to point to Polaris.
30. 30. Constellation for a certain month: March Night Sky 9pm
31. 31. June Night Sky 9pm
32. 32. September Night Sky 9pm
33. 33. December Night Sky 9pm
34. 34. An observer from Earth will be able to see the stars that are on the night side. The stars on the same side as the sun cannot be seen because sunlight overpowers all the star lights. During summer in the Philippines, the constellations of Orion and Taurus are not visible at night. They will be visible again as the cold season begins. During this time, Scorpius will not be seen in the night sky. As the Earth revolves around its orbit, the stars that were concealed by the bright light of the Sun in the previous months will appear in the night sky.
35. 35. How Early People Used the Constellations While constellations were associated with religion, they also have practical uses. Before the calendars, people had no way of determining when to sow or harvest except by looking at these patterns in the sky. Ancient people developed a way to remember the patterns by giving these patterns names and stories. For example, in the northern hemisphere, the constellation Orion indicates the coming of cold season. The constellations made it easier for them to recognize and interpret patterns in the sky.
36. 36. For example, Gemini is seen in the Philippines during the months of April and May. Farmers interpreted the appearance of Gemini as the end of planting season and it signified rich harvest. The table below shows how the Matigsalug Manobo of Bukidnon used the stars and constellations in relation to their agriculture.
37. 37. Local Name Month of Appearance Related Agricultural Act. Western Equivalent Baha Dec to Feb Clearing of forest Taurus Pandarawa January Start of planning what crops to be planted & how wide is the area Pleiades Balatik Feruary Start planting & setting of traps Orions Belt Malihe March Planting of rice,corn & veggies Gibbang April & May End of planting season, signifies rich harvest Gemini Malara May Stop planting Canis Minor
38. 38. Lepu Late May Time to clean or clear the fields while waiting for harvest time Aquila Buwaya June Start of the rainy season
39. 39. Other Uses Another use of constellations was in navigation. The Polaris is widely used in navigation because it does not change its position at any time of the night or year. Also, one can figure out his/her latitude just by looking at how high Polaris appears in the night sky. This allowed sailors to find their way as they sail across the seas.
40. 40. Group Activity In groups of five, observe the sun by capturing its image on a cardboard. Obtain a telescope and a square of white cardboard. Let one member hold the cardboard while another member holds the telescope in a reversed viewing position in order to capture the image of the sun onto the cardboard. DO NOT LOOK DIRECTLY AT THE SUN! Adjust the board and the telescope so that the image of the sun falls on the board. Focus the telescope until the suns image becomes sharp. Try to identify sunspots and prominences.