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Prepare your scantron:. Use a pencil, not a pen!. Setup:. Fill in your name and fill the bubbles under your name. LAST NAME FIRST, First name second Put your 4-digit code instead of “ IDENTIFICATION NUMBER ”. Scantrons must be turned in by each student in person ,

shelley-reese
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  1. Prepare your scantron: Use a pencil, not a pen! Setup: • Fill in your name and fill the bubbles under • your name. • LAST NAME FIRST, First name second • Put your 4-digit code instead of “IDENTIFICATION NUMBER”. Scantrons must be turned in by each student in person, not by a classmate! Question # 1: answer A Question # 2: answer B Question # 3: answer B Test I: next Wednesday, during class time. (Use the website at: http://www.phy.olemiss.edu/~ttorma/Astro/index.html and the presentations, tests links in there. Please take a moment to mute your cell phone!

  2. Stars in the telescope How many stars are visible to the naked eye? - around 6,000 only! Star in a telescope, magnified: Star with naked eye: Star in a telescope: Stars twinkle because air moves (wind blowing). Stars look really like only dots in a telescope: • too much magnification only blurs their image • reason why: stars are too far away to resolve their disks

  3. Questions coming …

  4. sec 24 20 21 22 23 26 25 17 27 28 29 30 18 0 16 1 14 13 12 11 10 7 15 9 6 5 4 3 2 8 19 Question 4 How many stars are visible to the naked eye? A A few hundred BA few thousand CA few millions D A few billions E A few hundred billions Next question coming …

  5. sec 14 45 40 35 30 25 19 18 17 16 13 15 11 0 1 2 12 4 3 7 8 9 10 6 20 5 Question 5 What surface details can we see on stars with a telescope? A Stars look large in the telescope with a lot of detail on their disks, but because they are gas balls, they have no surface. BNone. Stars are dots in any good telescope, blurred only by the motion of the air. CSome surface detail is visible in a good telescope, but not much, because stars are very far away. D Stars are magnified in large telescopes and their surface is visible in small detail. E No detail is visible on the surface but the shape of the disk of a star is resolved. Next question coming …

  6. sec 0 24 20 21 22 23 26 25 1 27 28 29 30 18 17 8 15 14 13 12 11 10 9 16 7 6 5 4 3 2 19 Question 6 Why do stars twinkle? A Because the wind blows clouds in front of them. BBecause they keep changing in size. CBecause they keep changing their temperature. D Because of the turbulent motion of air. E Because explosions keep happening on the surface of stars.

  7. Understand brightness of stars:the magnitude scale Brightness of stars An m = 10mg, star, need an amateur telescope to see it The Andromeda Galaxy m = 3mg in total An m = 17mg, star, need a professional telescope to see it Magnitudes mean brightness: • The larger the number, the fainter the object • One magnitude difference means a lot dimmer (2.5 times); five magnitudes is 100  A fifth magnitude star: m = 5mg,, just visible to the naked eye A third magnitude star: m = 3mg A second magnitude star: m = 2mg A first magnitude star: m = 1mg

  8. 4.0 mg Stars in the Big Dipper 1.9 mg 2.2 mg 3.3 mg 5.6 mg

  9. Questions coming …

  10. sec 24 20 21 22 23 26 25 17 27 28 29 30 18 0 16 1 14 13 12 11 10 7 15 9 6 5 4 3 2 8 19 Question 7 What does the magnitude of a star mean? A How bright the star is in reality. BHow bright the star appears in the sky. CHow large the star is in reality. D How large the star’s disk appears in the telescope. E How far the star is from Earth. Next question coming …

  11. sec 24 20 21 22 23 26 25 17 27 28 29 30 18 0 16 1 14 13 12 11 10 7 15 9 6 5 4 3 2 8 19 Question 8 Which one is brighter, a 1mg star or a 6mg star, and how much? A The 1mg star is six times brighter. BThe 1mg star is a hundred times brighter. CThe 1mg star is six times fainter. D The 1mg star is a hundred times fainter. E The question makes no sense because magnitude means size, not brightness. Next question coming …

  12. sec 24 20 21 22 23 26 25 17 27 28 29 30 18 0 16 1 14 13 12 11 10 7 15 9 6 5 4 3 2 8 19 Question 9 Do you need a telescope to see Pluto whose brightness is a 14mg? A No, it can be seen by the naked eye. BYes, but a pair of binoculars will do. CYes, and a fairly large telescope is needed to see it. D It is so faint that only the largest telescopes in the world can see it. E It has never been seen in visible light at all. Next question coming …

  13. sec 0 24 20 21 22 23 26 25 1 27 28 29 30 18 17 8 15 14 13 12 11 10 9 16 7 6 5 4 3 2 19 Question 10 Uranus is 6mg, Neptune 8mg. This means that A Uranus is fainter. BNeptune is fainter. CUranus is larger. D Neptune is larger. E Neptune is farther.

  14. This is how Orion looks to a naked-eye observer in complete darkness. Exercises on magnitudes 1   Orionis: 0.5 mg Orionis is one of the brightest stars in the sky. How bright do you think it is? How bright do you think Orionis is?  Orionis : 2.0 mg   Orionis : 4.3 mg How bright do you think Orionis is? 

  15. Capella is 0 mg. How bright do you think the following are? Exercises on magnitudes 2 Pleiades 2 mg • 1 mg International Space Station Aldebaran 1 mg - 4 mg Venus - 2 mg Jupiter

  16. What phase is this? By the way, what phase of the Moon is this?

  17. Lunar eclipse A lunar eclipse: the shadow of Earth falls on the Moon (may occur at full moon - not every time) Same eclipse for everyone on Earth: once a year on average

  18. Questions coming …

  19. sec 24 20 21 22 23 26 25 17 27 28 29 30 18 0 16 1 14 13 12 11 10 7 15 9 6 5 4 3 2 8 19 Question 11 What causes a lunar eclipse? A The shadow of the Moon. BThe shadow of the Earth. CThe fact that the orbit of the Moon is not a circle. D Interstellar dust. E Clouds. Next question coming …

  20. sec 24 20 21 22 23 26 25 17 27 28 29 30 18 0 16 1 14 13 12 11 10 7 15 9 6 5 4 3 2 8 19 Question 13 Assume there is a total lunar eclipse now at your location at midnight. Another person is looking at the Moon 200 miles away from you. What will s/he see at the same time? A No eclipse. BA partial lunar eclipse. CA total lunar eclipse. D A partial solar eclipse. EA total solar eclipse. Next question coming …

  21. sec 0 24 20 21 22 23 26 25 1 27 28 29 30 18 17 8 15 14 13 12 11 10 9 16 7 6 5 4 3 2 19 Question 14 How often is there a lunar eclipse in a particular place on Earth? A Every day except at full Moon. B Once every month. C About once a year. D About once a century. E About once in five hundred years.

  22. Turn in your scantron now in person!

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