Transcript The Sun
Prepare your scantron: Use • Fill in your name and fill the bubbles under a pencil, your name. not a pen! • LAST NAME FIRST, First name second • Put your 4-digit code instead of “IDENTIFICATION NUMBER”. --- (The last 4 digits of your OleMiss ID.) Note: Monday’s review questions include all about the Sun. Question # 1: answer A Setup: Question # 2: answer B Question # 3: answer A Reading assignment Chapter 14 (The Sun), pp. 464 – 485 Please take a moment to mute your cell phone! This question counts double! Question 4 How bright would the Sun look in the sky from a distance of 10 parsec? A -12mg (as bright as the full Moon). B 1mg (as bright as the brightest stars in the sky). C 5mg (barely visible to the naked eye). D 15mg (very faint). E Invisible: we cannot see that far. 30 29 12 13 14 15 16 17 18 20 21 22 23 24 25 26 27 28 10 11 8765432109 19 sec Next question coming … This question counts double! Question 5 The brightest star in the sky, Sirius, is m = -1.6mg. Its absolute magnitude is M = 0mg. Watched from the same distance, would Sirius look brighter or dimmer than the Sun? A A million times brighter. B A hundred times brighter. C About the same. D A hundred times fainter. E A million times fainter. 30 29 12 13 14 15 16 17 18 20 21 22 23 24 25 26 27 28 10 11 8765432109 19 sec Sunspots “Cold spots” in the photosphere Undisturbed photosphere (6000 K) Penumbra Umbra (5000 K) (4000 K) where convection is stopped by the magnetic field The basic law of magneto-hydrodynamics: Hot plasma cannot cross magnetic field lines. Sunspot details What are sunspots? (1) Convection brings up magnetic field (2) Strong field stops convection (3) Spot cools off (only 4000 C) Questions coming … Question 6 Where in the Sun is heat being produced? 30 29 12 13 14 15 16 17 18 20 21 22 23 24 25 26 27 28 10 11 8765432109 19 A Everywhere inside the Sun. B Only in the core (close to the center). C Only in a narrow region close to the surface. D In most of the Sun except in the convective outside region. E Nowhere, because no more energy is being produced in the sec Sun now. It has been heated up once and it is only giving off its heat as it is cooling off. Next question coming … Question 7 30 29 12 13 14 15 16 17 18 20 21 22 23 24 25 26 27 28 10 11 8765432109 19 What are sunspots? sec A Regions on the Sun, hotter than the photosphere. B Regions on the Sun, composed of dark substances. C Regions on the Sun, colder than the photosphere. D Holes in the surface of the Sun where we see deep into the Sun. E Clouds floating over the photosphere. Next question coming … Question 8 Which of the following explains what granules are? A The strong heat from below causes cracks on the surface of the Sun. 45 25 30 35 40 12 13 14 15 16 17 18 19 10 11 20 4321087659 sec B Rising hot bubbles reach the surface and glow until they cool down and sink. C The magnetic field of the Sun makes gas glow when charged particles cross it. D Clouds float over the photosphere. E Asteroids keep falling into the Sun and burn up in the Next question coming … intense heat. Question 9 What causes the sunspots? 45 25 30 35 40 12 13 14 15 16 17 18 19 10 11 20 4321087659 A The magnetic fields of the Sun deflects sunlight from the spots, so they appear dark. B The magnetic field of the Sun channels dark sec substances into sunspots. C The magnetic field of the Sun stops hot bubbles of gas from rising, causing the region to cool off. D The gravity of the Sun heats up the gas, which burns quickly and the remaining ashes are dark. E The shadow of the Moon is cast on the Sun, covering dark regions. (# of spots) + 10 x (# of groups) The 11 year solar cycle Solar maximum • Many large sunspots • Flares • Prominences • Eruptions Solar maximum Weather affected strongly Prominences Seen in H light (only) Gas follows Magnetic field lines Solar flares Magnetic heating causes nuclear explosions Rare event: -once in a month at solar maximum - flare lives for ten minutes Do not confuse flares with prominences: Spits out a lot of gas • flares are rare and may cause eruptions or prominences - gas may leave the Sun • prominences need not originate in flares Eruptions and prominences Eruption Watch the Soho movie! Filament (a prominence seen in the face of the Sun) Prominence Questions coming … Question 10 What is on the picture? A A sunspot. B A prominence. C A solar flare. 30 29 12 13 14 15 16 17 18 20 21 22 23 24 25 26 27 28 10 11 8765432109 19 sec Next question coming … Question 11 What is the “solar cycle”? 45 25 30 35 40 12 13 14 15 16 17 18 19 10 11 20 4321087659 A Every eleven years the Sun is more active and has a lot of sunspot, followed by years of relative quiet. B Once in year sunspots cause disruptions in the sec magnetic field of Earth. C Nuclear reactions heat up the Sun hotter than normal for a few months every year, and this causes summer. D Holes in the surface of the Sun where we see deep into the Sun. E The energy production in the Sun oscillates with a period of a few hundred years. Next question coming … Question 12 What is on the picture? A A sunspot. B A prominence. C A solar flare. 30 29 12 13 14 15 16 17 18 20 21 22 23 24 25 26 27 28 10 11 8765432109 19 sec Next question coming … Question 13 Look at the Sun through a telescope in regular light (no colored filter) at a random time. You have a good chance of seeing the following: A Sunspots, solar flares and prominences. B Sunspots, solar flares. C Sunspots. D Sunspots and prominences. E Solar flares and prominences. 30 29 12 13 14 15 16 17 18 20 21 22 23 24 25 26 27 28 10 11 8765432109 19 sec Turn in your scantron now personally!