AST 2003 1st EditionExam # 1 Study Guide Section 1General -Polaris (pole star, North star,)-all stars seem to rotate around the pole star-1 AU = distance from Earth to Sun ()-Our galaxy = 17 million light years across -88 constellations noticed todayPluto -Pluto is located in the Kuiper belt-Tombaugh discovered PLuto-Tyson demoted PlutoPeople-Ptomey- 48 constellations -Tycho Brahe- known for his inventions of precise viewing instruments before the telescope -Cladius Tomley- calculated zodiac “movements in the sky effect life”-Charles Messier- created catalogue of 110 comets-Chandrashakar- Indian astronomer, election degeneracy, “with enough material + gravity = chaos”-Henrietta Leavitt- studied variable stars, made key for finding distance to starsMagnitude Scale-Hipparchus-classified stars according to brightness -higher the number, the fainter the star-human eye can see down to 6th magnitude-the brightest stars have proper names: Rigel BetelgeuseMotion of the Night Sky-depends on location-sun appears higher in the sky during summer (longer days)-sun appears lower in the sky during winter (shorter days)-Culminate: when stars are at their highest point due south-Observer’s meridian-Declination- [dec> (90-lat) are circumpolar][dec< (90-lat) are not seen]Motion of the Earth-anticlockwise-rotates every 23 hr 56 min-orbits every 365.25 days-the tilt of the Earth’s axis is what causes the seasons-Axis of rotation- 23.5 degrees-Summer- sun is above celestial equator-Winter- sun below celestial equatorConstellations Orion (Winter)-hunter -pursued 7 sisters (Pleiades)-killed by scorpion Tarus (Winter)-Crab Nebula (6300 Lys)Canis Major (Winter)-the great dogGemini (Winter)-twinsSummer Triangle -Cygnus, Lyra, Aquila, -brightest stars: Altair, Deneb, and VegaTerms and extra materialParallax- taking tiny measurements overtime SETI- Search for Extraterrestrial IntelligenceNGC-New General CatalogueCelestial poles-directly above Earth’s polesCelestial equator-directly above Earth’s equatorDeclination- degreesRight ascension- hr, minCircumpolar circle- circle around the pole star where circumpolar stars reside Aphelion-farthest to the sunPerihelion- closest to the sunFirst point of Aries-point where sun crosses celestial equator heading North (sometimes Vernal equinox)Circumpolar constellations-Cepheus -Perseus-Uras Major-Ursa Minor-Camelopardalis-Cassiopeia-DracoM101- Pinwheel GalaxyM42- The Orion NebulaIC434 + B33- Horsehead Nebula M9- Owl NebulaM31- farthest to see with the naked eye47- Ursae Majoris 47th brightest, similar to the sun, 46 Lys awayM81 + M82- “Arch” discovered by Charles MessierAlgol- eclipsing binary starAndromeda galaxy- 2.2 million LysHelix Nebula- “god’s eye”Planetary Nebula- ring around the star after explosionFamous double star- Mizar, Alcor-Uranus and Venus are the only two planets that spin