Prepare your scantron: Use a pencil, not a pen! 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”. --- (The last 4 digits of your OleMiss ID.) Question # 1: answer A Question # 2: answer C Question # 3: answer B Setup: Pass/fail makeup: Wednesday 5:00 pm Please take a moment to mute your cell phone!

Review questions coming …

This question counts double! sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 4 A nebula usually has a … spectrum. A dark B continuous C ultraviolet. D emission E transparent Next question coming …

This question counts double! sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 5 What is the substance of the photosphere of the Sun? A Solid. B Liquid. C (At least partially) ionized gas. D Molecules. E A gas of purely neutral hydrogen atoms (H, but not H+, or not H2). Next question coming …

This question counts double! sec 8 9 11 7 10 4 1 2 3 13 6 12 25 30 35 40 14 19 16 15 17 18 45 20 5 Question 6 What is ionization? A Molecules fall apart into atoms due to heat. Glowing gas is formed. B Nuclear processes in stars produce dangerous radiation. C Atomic nuclei fall apart into neutrons and protons. A neutron star results. D Atoms lose (some of) their electrons due to heat or UV radiation. The substance becomes plasma. Next question coming …

This question counts double! sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 25 27 28 30 29 17 24 19 18 23 20 22 21 Question 7 What type of spectrum does a glowing solid body have? A absorption spectrum. B emission spectrum. C continuous spectrum. D infrared spectrum. E ultraviolet spectrum.

Cosmic rays From Deep Space (??) The Solar Wind protons, electrons Earth’s atmosphere and magnetic field absorb them (dangerous for astronauts) very energetic protons & nuclei Break up into showers of many less energetic particles in the atmosphere. (always present: causes mutations)

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sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5 Question 8 Which of the following causes a measurable amount of radiation, present on Earth? The Solar Wind. “Deep Space” cosmic rays. Radiation from nuclear reactors. Radiation from naturally occurring decays. A I and III. B II and IV. C I, II and III. D None of the above. E All of the above.

(Joseph von Fraunhofer, 1814) The device that resolves the colors of light: the spectroscope (Joseph von Fraunhofer, 1814) • Light from telescope enters slit (to block off stray light) • Prism (or grating) separates the colors • Produces spectrum on a screen/on a film (Put this device in a box and attach it to the telescope) The spectroscope Surprise: The spectrum of the Sun has black lines: Some colors are missing! (Fraunhofer-lines) Spectrum: each color is a “line”

The spectrum of the Sun Absorption lines (“Frauenhofer-lines”), (Color and b/w version of the same thing.) H H Absorption lines (“Frauenhofer-lines”), many in hydrogen wavelengths Here: colder gas takes out a few colors Solar atmosphere

the chemical composition Types of spectra Continuous spectrum (thermal glow & synchrotron radiation) Absorption spectrum (gas illuminated from behind) Emission spectrum (rarified gas: fluorescence) Each chemical element has its own spectral lines: A good way to tell the chemical composition of a star!

The spectra of stars – the effect of photospheric temperature

Questions coming …

sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5 Question 9 How do we know that the Sun is made mainly of hydrogen? A Its density equals the density of hydrogen. B Spaceships brought back a samples from the Sun. C Its spectrum contains hydrogen lines. D The gravity of the Sun can be explained only by hydrogen gas. E Only burning hydrogen (and no other gases) can produce enough heat to explain why the Sun is hot. Next question coming …

sec 10 9 11 13 14 8 12 7 2 1 3 4 6 5 15 17 26 25 27 28 30 29 16 24 19 18 23 20 22 21 Question 10 Which one of the following types of spectra indicate the presence of cold gas located between a star and Earth? A Absorption spectra. B Emission spectra. C Continuous spectra. D Line spectra. E Band spectra.

sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 11 The spectrum of the Sun consists of A a few bright lines only. B dark lines over a bright continuum. C dark bands of light with bright centers, over a bright continuum. D a continuous bright spectrum like a rainbow. E a few bright bands with dark centers. Next question coming …

The effect of movement on spectral lines: The Doppler effect • Light source moves towards observer: spectral lines are shifted towards blue • Light source moves away from observer: spectral lines are shifted towards red • Light source moves sideways: no change

The spectrum of another star The Sun H H Polaris Spectral lines shifted towards blue: Polaris is approaching us Measure shift: find radial speed 17 km/s Why are the spectral lines shifted? -- the Doppler effect

Questions coming …

sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5 Question 12 In what are spectra of other stars different from the Sun’s? A The same spectral lines are there in every star’s spectra, but they may be shifted if the star is moving. B Different spectral lines may be visible, in addition to Doppler-shift. C All stars have the same spectrum because they are all made of gas. D The spectrum is the same, except that the blue part of hotter stars’ spectra is brighter. Next question coming …

sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5 Question 13 What is the Doppler effect? A Stars move on tiny circles in the sky, once a year. B The stars appear red when they are rising or setting. C Far-away stars appear red because the Universe is expanding. D The spectral lines of a star are shifted towards red, if the star is moving away from us, and towards blue, if the star is approaching us. E A fast moving star’s spectral lines are shifted towards red, independently of the direction of motion. Next question coming …

sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 14 A particular galaxy is moving away from us with large speed. Which of the following happens to its spectrum? A The spectral lines show up shifted towards red. B The spectral lines show up shifted towards blue. C The color of the galaxy becomes redder. D The color of the galaxy becomes bluer. Next question coming …

sec 10 9 11 13 14 8 12 7 2 1 3 4 6 5 15 17 26 25 27 28 30 29 16 24 19 18 23 20 22 21 Question 15 Which of the following happens to the sound of the whistle coming from a train approaching us at high speed? A It becomes lower-pitched. B It becomes higher-pitched. C It becomes less loud. D It becomes more loud.

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