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Key Phys 102 Astronomy Name _____________________ EXAM 2: LIGHT AND STARS: BRAIN AND PENCIL This part of the exam is to be completed by yourself with no references. When you finish, hand it in, pick up the Group part of the exam. 1)12 Complete the following table: CELESTIAL EVENT DEFINITION VERNAL SUN ON CELEST. EQ. EQUINOX MOVING NORTH SUMMER SUN AT NORTHERNMOST SOLSTICE POINT AUTUMNAL SUN ON CELEST. EQ. EQUINOX MOVING SOUTH WINTER SUN AT SOUTHERNMOST SOLSTICE POINT α δ HOURS DEGREES CONSTELLATION (NAME) SUBSOLAR LATITUDE APPROX. DATE 0h 0° Pisces Equator 3/21 6h +23.5° Taurus Tropic of Cancer 6/21 12h 0° Virgo Equator 9/21 18h -23.5° Sagittarius Tropic of Capricorn 12/21 Multiple Choice: circle the best answer (or split the points by circling two) 2)2 The color of a star is a direct measure of its a) mass. b) temperature. c) velocity. 3)2 The moon’s current phase is a) waxing crescent. b) waxing gibbous. c) waning gibbous. d) waning crescent. 4)2 Today the sun will set a) south of due east. b) south of due west, c) north of due east, d) north of due west, 5)2 The celestial equator is a) the path of the sun across the stars. b) a cosmic referee who is responsible for making things "fair." c) the projection of the earth's equator onto the celestial sphere. d) the line from due north to due south that passes through the zenith for an observer. 6)2 One element differs from another in a) the number of neutrons. b) the number of electrons. c) the number of protons. Stars E n e r AOD 4/3/2006 A B Wavelength 7)2 Of the two stars whose continuum spectra are shown a) A is cooler. b) A is more distant. c) B is cooler. d) B is more distant. 8)2 An atom is said to be in an excited state when a) it visits California. b) electrons are removed. c) electrons are in higher energy levels than normal. 9)4 Tonight, (Mar. 29) ρ Leo, a B0I supergiant, will transit at 10:04 PM. On what night will it, or did it transit at 10:00 PM? (Sketch it to help yourself figure it out ... tonight’s situation is shown) a) March 25th. Observer’s b) March 28th. Meridian c) March 30th. d) April 2nd (March 33rd). 10)2 Total Eclipses of the sun can only occur when a) the moon is new. b) the moon is full. c) the line of nodes is perpendicular to the Earth-Sun line. Sol @ 10:04 pm 11)2 If you see the moon rising at 3 pm, the phase must be a) waxing crescent. b) waxing gibbous. c) waning crescent. The birth of dawn from sun and darkness is a d) waning gibbous. mystery very sacred though it happens every day. ‐‐ Pawnee song 12)2 The declination of a star is a) the angle between it and the celestial equator. b) the angle between it and the horizon. c) the angle between it and the point of Aries. 13)2 The altitude of a star is a) its height above the ground. b) its angle from the celestial equator. c) its angle above the observer's horizon. 14)2 The Sun is an average star of spectral type a) G5 II. b) G2 V. c) F3 IV. Page 2 Stars AOD 4/3/2006 15)10 Identify the phase of the moon in the following images: Phase: 3rd Quarter Phase: Phase: Waxing Gibbous Phase: New Full Phase: 1st Quarter 16)9 label the diagrams below with the sun and the moon (in the appropriate phase) for observations of the moon with the given elongations and times. The observer is looking south, into the page. E W a) 90° W @ 3 PHASE: st AM 1 Quarter ______________ E W b) 135° E @ 3 PM PHASE: Wax. Gibbous ______________ 17)8 For the images to the right, explain what they tell us about star formation and evolution. What stage does each represent? Has or will our sun go through a similar stage? Name at least one nebula (and its constellation) where stars are at the same stage in life. The top image is of a planetary nebula (with a central white dwarf). It shows the death stage of a small (sunsized) star and Sol will go through this stage in about 5 billion years. Another such nebula is the Ring Nebula in Lyra. The lower image is of a star formation in the Eagle Nebula in Serpens. In this image, the stellar wind from a bright star to the upper right is evaporating the gas and dust, leaving dense evaporating gaseous globules (EGGs) where stars are forming. The sun may have gone through this 5 billion years ago when it formed. Page 3 E W c) 45° E @ 6 PM PHASE: Wax. Crescent ______________