astronomy

astronomy - 17:08 1/11/12 SIZE AND SCALE Sun (1.5 million)...

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17:08 1/11/12 SIZE AND SCALE Sun (1.5 million) is 100 times bigger than Earth  Earth -> Sun -> Galaxy Distance= speed x time or v= d/t 1 Light Year = c (speed of light) x 1 yr   c= speed of light; 300,000 km/sec = 3 x 10^5 km/s   or     3x10^8 m/s closest star= 4.3 LY  Constellations (Celestial Coordinates       “       Spheres ) longitude 360 degrees rotation: right ascen: 24 hr latitude: declination -90 d <-> + 90) NOT on test 1/13/12 Celestial Sphere:  North celestial pole: Polaris (relatively bright)
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If standing in north pole, direct up to see Polaris  South celestial pole  Stars rise east and sets to west: moves from east to west Zenith: straight up  Circum polar stars: never rise or set  Standing at the north pole, all around  At the equator, NONE  Earth rotates counterclockwise (West to east); top to bottom  Sky rotating around us  Astronomical Time 1 Solar day= the amount of time it takes for  = 24 solar hours  meridian: north to zenith to south  1 sidereal (stars) day = 24 sidereal hours = 23:56 solar hours:min 4 min difference  Rotation = spin Revolution = orbit  Angle (theta)=1 day x (360 deg/365 days) = .986 deg =approx. = 1 deg Change in time= 1 deg x (24hr/360 deg) x (60min/1hr) = 4 min
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1/18/12 SEASONS: Why hotter in summer? length of day <-> duration of illumination sun’s angle above. Horizon at midday -> direct of illumination (does affect temperature.  Every per unit area)  Terminator= line distinguishing day and night  Northern hemisphere- illuminated (related to amount of time exposed to the sun) Summer Solstice: 1 st  day of summer (hemisphere dependent; north or south) longest day of year sun highest in sky at midday  Winter solstice 1 st  day winter shortest day of year sun lowest in sky at midday 1 st  days spring and fall 
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12 hours of day 12 hours of night  Precession:  Asymmetric and aspherical (not spheric) mass distribution  External force  Same for earth? Earth is spinning; mass distribution changes 10% bigger across the middle  1/20/12 MOON Lunar Phases: depends on direction of illumination and viewing (where you’re standing) -moon’s up half of night and half of day  Lunar Month: Sidereal (star) Month: 27.3 days  Synodic (phase) Month: 29.5 days  Calendar Month: General months; 28/30/31 days  Lunar Rotation: 
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Lunar Eclipse: Sun -> Earth -> Moon  Red scatter smaller range, blue scatter out more; less blue hits the moon giving the 
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This note was uploaded on 02/23/2012 for the course ASTR 101 taught by Professor Christiansen during the Spring '08 term at UNC.

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astronomy - 17:08 1/11/12 SIZE AND SCALE Sun (1.5 million)...

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