Viewing the Night Sky Constellations Constellations are configurations

Viewing the Night Sky

Constellations Ø Constellations are configurations of the brightest stars l Ø Named by ancient astronomers after mythological beings Different cultures made different interpretations of same star configurations

Who cares about constellations? Ø Ancient astronomers used them as: l l Navigational guides Primitive calendars to predict planting and harvesting seasons Ø 88 constellations TOTAL

Astrology vs. Astronomy Ø Astrology – use of relative position of stars and planets at a person’s birth to make predictions about destiny l l l Wanted to “see into the future” Why doesn’t it work? Stars that make up any particular constellation are NOT close to each other, but happen to lie in same direction when viewed from Earth

THE CELESTIAL SPHERE Celestial sphere – a canopy of stars resembling an astronomical painting on a heavenly ceiling (what we see ½ of when we look up) Ø APPARENT MOTION of stars is due to Earth’s rotation—the stars are not actually moving. Ø

Ø Celestial poles – the points where the Earth’s axis intersects the celestial sphere Ø Celestial equator – midway between the north and south celestial poles

Ecliptic & the Milky Way Ecliptic – the apparent simple path the Sun takes as it circles the celestial sphere Ø Milky Way – whitish band of light in the sky Ø l l Stretches all the way around celestial sphere Relates to Milky Way Galaxy because: • IT TRACES THE GALACTIC PLANE AS IT APPEARS FROM OUR LOCATION IN THE OUTSKIRTS OF THE GALAXY

My Notes (+) from Dark Skies Because of Light Pollution, 70% of Americans cannot see the Milky Way. Flagstaff Dark Skies Coalition: § Their mission is to “celebrate, promote, and protect the glorious dark skies of northern Arizona”. § Believe people should be able to experience “seeing the stars” § Helping to set regulations for building lights § Fewer § Glare-free § Lower wattage International Dark Sky Association: § Developed to protect our views of the night-skies. § How are we doing in North Bend-Snoqualmie? http: //www. blue-marble. de/nightlights/2010

The DOME OF THE SKY Ø Local sky – the sky as seen from wherever you happen to be standing Ø Horizon – the boundary between Earth and sky Ø Zenith – directly overhead Ø Meridian – an imaginary half-circle stretching from your horizon due south, through zenith, to your north horizon Ø ZODIAC – constellations along the ecliptic

Dome of the Sky (continued) Ø We cannot tell the true size of or between objects in space by looking at them Ø Angular size – the angle it appears to span in your field of view Ø Angular distance – the angle that appears to separate two objects l Use your hand for rough measurements

Stargazing Basics 1: Learn How to Get Oriented in the Night Sky for Stargazing https: //www. youtube. com/watch? v=XUb. G 8 jboh 4 M&feature=player_detailpage

A few more notes on your location Your latitude determines your orientation on Earth relative to celestial sphere Ø A few rules: Ø Circumpolar – stars that never rise or set but instead make daily counterclockwise circles around NCP Ø

Where are the other stars? In South Hemisphere, stars near NCP are never seen! Ø All other stars (not circumpolar or never visible) rise and set daily Ø Altitude of NCP in your sky = latitude Ø