Week two Notes
Week two Notes AST 111
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This 6 page Class Notes was uploaded by Ashley Childers on Friday August 28, 2015. The Class Notes belongs to AST 111 at University of Southern Mississippi taught by Christopher Sirola in Summer 2015. Since its upload, it has received 38 views. For similar materials see General Astronomy in Physics 2 at University of Southern Mississippi.
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Date Created: 08/28/15
Astronomy Week 2 Notes Cygnus the Swan Description shows a swan diving head rst into t 39 Myth Ancient Greek ltt is important to note that the Ancient Greeks view the Earth as a at diskgt Helios the original sun god has a son named Phaethon with an ocean nymph The son boast to his friends that his father is the god of the son no one believes him so he sets out to show them Phaethon ask his father to grant him one wish and without thinking Helios agrees He wishes to drive the sun chariot across the sky the next morning So in keeping to his promise Helios agrees on the one condition that his son stay on the path in the sky The next day Phaethon is ying along driving the chariot when he spots his village however he knows that he has to do something to prove that it is him driving So he decides to pay a visit He ies closer and closer until he notices that everything is on re and people are screaming so he turns and races back far away This simply makes the world freeze so he darts close than farther again gaining the attention of Zeus king of the gods who can t allow the humans to be destroyed so he shots Phaethon with a lightning bolt He then falls out of the sky into the local river Eridanus To the shock of his best friend Cygnus who was watching the whole event unfold from the bank Cygnus then dives into the water to search for his friend Over and over again he dives until after what seems to be hours does he nd the body and drags it back to shore Cygnus then dies on the shore from pure exhaustion ln sympathy the gods turn him into a swan and memorialize him in the stars Science Deneb bluewhite supergiant thousands of times brighter than the sun and very far away Deneb is located RA 20h 41m Dec 46d 17m light year distance light can travel in a year in empty space about 6 trillion miles 6000000000000 r Aquila the Eagle Location near the milky way galaxy39 Myth Goddess Hebe youth she is the cupbearer waitress for the Olympians who marries the dead Hercules So the gods must replace Hebe Zeus nds a prince of Troy named Ganymede as new cupbearer Zeus sends his avatar the eagle to fetch him Now Ganymede is made immortal waiter In recognition of his services Zeus places the Eagle in the sky Science Altair bluewhite star a bit lighter and brighter than the sun 0 Lower tip of the summer triangle 0 RA 19h 51m 0 Dec 08d 52m Radio observations show that Altair rotates very rapidly for a star once every 89 hours Altair s equator has radius of 20 solar radii but the radius at the poles of Altars is only 16 solar radii Various temperature differences Due to lower surface gravity and temperature at its equator Altair is brighter at poles that equator not typical Units of Space Local Coordinates Azimuth angle of object around horizon Horizon divides Earth from sky Zenith directly above ones head Altitude angle of object above horizon 090 Meridian divides east from west Global vs Local altazimuth is a local system used at one s own location on earth Constellations Combination of quotconquot with and quotstellaquot star Modern constellations are official groupings of stars Asterism unofficial grouping of stars Space in three dimensions what we see as at sky is actually a projection each star has its own distance and angular coordinates there are 88 official constellations that cover all areas of the sky many northern hemisphere constellations names taken from ancient greek many southern hemisphere constellations named by 15th and 16th century European sailors Units of space Celestial Coordinates Earth Longitude measures east and west Earth Lattitude measures north south poles and equator de ne the Earth Ea h 0 North pole Equator South pole Long ude Latitude Path of the sun Sky equivalent North celestial pole Celestial equator South celestial pole Right Ascension DecHnann o Ecliptic Right Ascension o Longitude 0 East west position 0 Divide full circle into 24 quothour anglesquot rather than 360degrees 0 Thus the object moves one hour per hour 0 Goes from 0 to 24 DecHnann o Latitude 0 North south position 0 Uses degrees 0 Goes from 90 degrees NCP through 0 degrees CE and to 90 SCP 00000 00000 O inelinetlen L reerth eeleetiel eele ee le etiel 1 he re eeleetiel eq meter 7 L m 39 if gt dieellnetien h gt l 71 7 7 139squ 1 Fl IEiEl39 v fair 2 2 Ler39restriel Leehere 7 7 Li Llu dm E i I 1 r L i 39 4 eelitie eernll equine rig hi 3 see he in n eeleetiel meridin Senath eeleetiel eele L Astronomy Chapter 1 Book notes De nitions Universe is the total of space time matter and energy Astronomy is the study of all the universe Light year distance travelled by light in a year inside the void of space 0 About 6 trillion miles Theory the framework of ideas and assumptions used to explain some set of observations and make predictions about the real world Theoretical Model prediction based on phenomenon that accounts for all of its known properties Scienti c Method process for combining theoretical reasoning with experimental testing Characteristics of a theory 0 Testable the theory must admit to the possibility of being proven right or wrong 0 Must continually be tested 0 Should be simple should not be more complex than necessary 0 Elegance naturally ties together and explains several phenomena previously though to be completely distinct Hypothesis one possible explanation of observed facts Constellations perceived patterns and relationships among the stars Celestial sphere a canopy of stars resembling an astronomical painting on a heavenly ceiling Rotation spin Celestial poles points where Earth s axis intercepts the celestial sphere Celestial equator representation of the Earth s equatorial plain in relation to the celestial sphere Solar day 24 hours as measured by the earths rotation Diurnal motion daily progress of the sun across the sky Sidereal day a day measured by the stars varies in length Revolution journey around the sun Ecliptic motion of the earth around the sun not quiet a circle Zodiac 12 major constellations Summer solstice the point at which the sun is at its north most point about the celestial equator Winter solstice point at which the sun is at the southern most point relative to the celestial equator Seasons the mark in temperature differences in various months caused by the Earth s rotational axis Equinoxes equal day and night two points where the ecliptic intersects the celestial equator Autumnal Equinox as the sun crosses from the northern to the southern hemisphere Vernal Equinox the sun crosses from the southern to the northern hemisphere Tropical year the interval of time between on vernal equinox to the next Precession caused by twisting forces on Earth due to the gravitational effects of the moon and sun Sidereal year time required for Earth to complete one orbit around the sun Phases regular cycle of changes moon Sidereal month the moon completes one revolution and returns to its starting point on the celestial sphere Synodic month the time required for the moon to complete one full cycle of phases Eclipse when the moon and sun line up perfectly as seen that the moon crosses in front of the sun Lunar Eclipse when the earth crosses between the sun and moon so that the moon is completely darkened by the Earth s shadow Solar Eclipse when the moon passes directly in front of the sun Umbra the region of space the moon s shadow needs to occupy for an eclipse to be seen Prenumbra region of space the moon can occupy for a partial eclipse to be seen Annular eclipse a special eclipse where the moon disk fails to fully cover the disk of the sun Eclipse seasons special times when eclipse s can occur Triangulation distance measurement method based on the principles of Euclidean geometry and nds widespread appHcann Cosmic distance scale a family of distance measurement techniques of which triangulation makes up the bases Baseline distance between two observation points using triangulation Parallax the apparent displacement of a foreground object relative to the background as the observer s location changes quotl niiillliin miles
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