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Download Part I: The Speed of Light Part II: Calcula ng a Light Year
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8.8D: Light Years Earth and Space Part I: The Speed of Light Fundamental Ques?on: What is the speed of light, and how far does it travel in one Earth year? 1. To find out how fast light travels per minute, mul<ply the speed by 60 seconds per minute. 300,000 km/sec X 60 sec/min = __________ km /min. 2. To find out how fast light travels per hour, mul<ply the answer above by 60 minutes per hour. __________ km/min X 60 min/hour = __________ km/hr 3. To find out how fast light travels per day, mul<ply our answer above by 24 hours per day. __________ km/hr X 24 hr/day = _____________ km/day 4. To find out how fast light travels per year, mul<ply the answer above by 365 days per year. __________ km/day X 365 days/year = __________ km/year. This is the distance light travels in one year. The unit you have just calculated is in the trillions. Part II: Calcula?ng a Light Year Fundamental Ques?on: How do astronomers measure distance? Let’s see how fast light travels from the Sun to Earth. Do you remember how to cancel zeros in a division problem? Use that method for the problems below. 1. Earth is 150,000,000 km from the Sun. Light travels at 18,000,000 km/min. How long does it take for light from the Sun to reach Earth? 2. The closest star to our Sun is Proxima Centauri. It is 39,700,000,000,000 km from the Sun. Light travels at 9,460,800,000,000 km/year. How long does it take light from the Sun to reach Proxima Centauri? 1 8.8D: Light Years Earth and Space Part III: Modeling Light Years -‐ The “Student-‐Minute” Fundamental Ques?on: How do astronomers measure distance? Walker’s Name: _________________________________________ Distance in 30 Seconds (meters) Trial Number 1 2 3 Average 1 Student-‐minute = _________ X 2 = _____________ meters (Average ) 1. How many meters are equal to 5 student-‐minutes? ____________________________________________________________ 2. How many student-‐minutes are equal to 100 m? ____________________________________________________________ 3. During this ac<vity, you were modeling a light year. In the model, what did we use instead of a “year?” ____________________________________________________________ 4. In this model, what represented the “light?” ____________________________________________________________ 5. How is a “student-‐minute” similar to a “light year?” _____________________________________________________________ ___________________________________________________________ 2 8.8D: Light Years Earth and Space Part IV: Traveling through Time Fundamental Ques?on: How long has light from other stars been traveling toward Earth? Complete the chart below. The first one has been done for you. Distance Star Time light has been traveling from Earth Sol 8.33 light-‐minutes 8.33 minutes Sirius A 8.6 light years Ross 154 9.68 light years Center of the Galaxy 26,400 light years 1. Imagine a planet 15 light years away from Earth that is inhabited by people like us. They have developed a very powerful telescope allowing them to see what is happening on Earth. If they look through their telescope today, what year would it be on Earth? Would they be able to see you? Explain. _____________________________________________________________ _____________________________________________________________ 2. On another planet, in the year 2010, they are looking at Earth and watching George Washington cross the Delaware River in 1776. How many light years away is this planet from Earth? _____________________________________________________________ _____________________________________________________________ 3. If there was a planet circling Ross 154 and inhabited by people, would those people be able to see your first birthday party on Earth? Explain. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ 3 8.8D: Light Years Earth and Space Reflec?ons and Conclusions 1. What travels the fastest in the universe? ___________________________________ 2. What is a light year? _____________________________________________________________ _____________________________________________________________ 3. Why do astronomers need to use light years, rather than kilometers, to measure the distance between stars? _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ 4. You are on a space ship that can travel the speed of light, and you are going to visit Proxima Centauri. Proxima Centauri is 4.2 light years away. How long would it take you to travel there? Explain your answer. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ 5. A scien<st wants to travel to the center of the Milky Way Galaxy. It is 26,400 light years from Earth. Would the scien<st ever reach his/her des<na<on? Explain your answer. _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ 4
