Transcript Parallax
Monday March 16 Tuesday March 17 Unit Question What do we know about the universe? How do we know it? Guiding Question / Learning Target How do we know what we know about the universe? Warm-up If a star is 8.2 light years away, how far is it, and how long does it take its light to reach us? Distance 8.2 LY (8.2 trillion Km) Time it takes: 8.2 years Agenda 1. Discuss Calculating Stellar Travel Times—get it out! 2. Parallax QUIZ FRIDAY! Homework Calculating stellar travel times Why does the Sun look different from other stars? CLOSER Why do astronomers use the distance light travels in a year to measure the vast distances between stars? Space is big, light year is big! Would it be practical to travel to Sirius by any of the modes of travel listed on the Travel To Sirius chart? Why or why not? NO.TIME! Do you think that it is possible that one of the Voyager spacecraft would ever be intercepted by a civilization around another star, even if such a civilization exists? NO. NEEDLE IN HAYSTACK. IF IT GOES BY INHABITED WORLD MAYBE BUT THEY HAVE TO BE LOOKING AT JUST THE RIGHT INSTANT What travels at the speed of light that is capable of carrying information? (Think of types of communication that we use everyday!) EM WAVES/RADIO/MICRO/CELL PHONE, LIGHT, ETC. What would be the most practical way to get information from Earth to Sirius if we knew that a civilization existed around this star? EM WAVE If perhaps the simulated message that had been received by a radio telescope here on Earth had come from Sirius, how long ago would it have been sent? Why? 8.2 YEARS, IT’S 8.2 LIGHT YEARS AWAY SETI scientists are listening to stars that are within 100 lightyears of Earth. Why do you think they have chosen this limited distance? TAKES 100 YEARS FOR SIGNALS TO GO OUT / BACK, CIVILIZATIONS CHANGE/DIE Proxima Centauri is the closest star to Earth at a distance of 4.3 light years away. If you stand outside on a clear night and see the light coming from it, how long ago did the light leave that star? Explain your answer. 4.3 YEARS AGO, LIGHT TRAVELLS 1 LIGHT YEAR A YEAR "Star Trek" is a TV show in which a starship goes to other star systems in our Galaxy. Can you think of any practical problems with this idea? TOO FAR AWAY 11. Super Nova 185 (AKA RCW 86) appeared suddenly in the night sky in AD 185. This “guest star” was seen around the world for about 8 months. The star that went supernova was about 8,000 light years from earth. What year did the star go supernova? How do you know? 7,815 BCE LIGHT TOOK 8,000 YEARS TO GET HERE,THAT’S 8,000 YEARS BEFORE PEOPLE SAW IT 12. What does the phrase “The deeper astronomers look into space, the farther back they see in time”? How is this true? WE CAN ONLY SEE LIGHT AS IT LOOKED WHEN IT LEFT, NOT AS IT CURRENTLY IS.THE FARTHER AWAY SOMETHING IS THE LONGER THE LIGHT HAS BEEN TRAVELING,THE “YOUNGER” THE OBJECT LOOKS. How is looking farther into space like looking back in time? Letter Match H Q L K P C M N O D F J A Important Historical Events Event Year Oldest stone tools 2.4 MYA Animals domesticated 10,000 BCE First zoo in China is founded 2,000 BCE Concrete used in Italy 200 BCE Chinese make steel 400 Rise of kingdom of Ghana in Africa 800 Marco Polo visits Mongol China 1275 1st popular printed math textbook 1478 Galileo develops a thermoscope, a primitive thermometer 1592 Telescope invented 1608 Peter the Great is Czar of Russia 1689 Roald Amundsen reaches South Pole 1911 Elizabeth II becomes Queen of England 1952 Sputnik (1st satellite) launched by USSR 1957 John Glenn orbits Earth 1962 First heart transplant 1967 Viking 1 & Viking 2 land on Mars 1976 Superconducting ceramic created 1987 First crew to Live aboard Space Station 2000 Parallax How do astronomers know how far away something is? One of the difficulties in Astronomy is measuring distance. One of the ways to measure distance is parallax. Parallax is the apparent shift in the position of an object when viewed from two locations. The nearer an object is to the observer, the greater its parallax. This activity will show how distance affects the amount of observed parallax. Set Up Place meter stick on table, with Ruler forming a “T” Set Up 3. Hold a pencil upright at the 20 centimeter mark. 4. Close your right eye, and record the number on the ruler that is covered by the pencil. 5. Close your left eye, and record the number on the ruler that is covered by the pencil. 6. Determine the observed parallax by finding the difference between these two numbers and record absolute value (no negatives!) Set UP 7. Move the pencil to 40 centimeters and repeat steps 4 and 5 8. Then move to 60 centimeters and repeat steps 4 and 5 9. Complete the table with information needed to determine observed parallax. Keep your head steady, open and close your eyes. Meter stick lined up with the end of the desk, chin with the meter stick. If you had stretch armstrong arms, is there a limit to how far away you could get before there was no apparent movement? Try it! Drawing Parallax You need 4 colors E is EARTH. Use EARTH for all the questions up to # 7. Color in your KEY so you don’t get confused when you go to each step Key: Earth A Earth B Mars A Mars B AB B A 6 months later Activity stamped before A.T. Conclusion questions: 7. What is it about our eyes that allow us to see parallax?