Astronomy The Study of the Universe Astronomy Azimuth

Astronomy The Study of the Universe

Astronomy • Azimuth, Altitude, Right Ascension, Declination • Constellations • Distances in Space • Parallax distortion • Spectra (absorption and emission) • Basic properties of stars – Diameter, mass, brightness, energy output, surface temperature and composition

Measuring Star Positions from Earth Method 1: • Azimuth: the angular distance along the horizon to the location of an object (usually starting from the North pole and moving East; 0 -360˚) • Altitude: the distance an object appears to be above the horizon. (0 -90˚) Method 1 is dependent on the location of an observer on Earth

Measuring Star Positions from Earth Method 2: (more common because of standardized coordinates) • Right Ascension (α) : – measured in hours (since the celestial equator is divided into 24 equal portions) – Each hour is divided into 60 equal minutes – 0 hour is the vernal/March equinox – Analogous to longitude • Declination (δ): – At the celestial equator (0˚), the north pole (+90˚), the south pole (-90˚) – Analogous to latitude

Understanding Declination Understanding Right Ascension

Will this system work forever? NO! What does this mean about astrology?

Constellations • Prominent luminous objects in the sky that seem to form patterns to observers on Earth • The International Astronomical Union (IAU) recognizes 88 constellations Andromeda · Antlia · Apus · Aquarius · Aquila · Aries · Auriga · Boötes · Caelum · Camelopardalis · Cancer · Canes Venatici · Canis Major · Canis Minor · Capricornus · Carina · Cassiopeia · Centaurus · Cepheus · Cetus · Chamaeleon · Circinus · Columba · Coma Berenices · Corona Australis · Corona Borealis · Corvus · Crater · Crux · Cygnus · Delphinus · Dorado · Draco · Equuleus · Eridanus · Fornax · Gemini · Grus · Hercules · Horologium · Hydra · Hydrus · Indus · Lacerta · Leo Minor · Lepus · Libra · Lupus · Lynx · Lyra · Mensa · Microscopium · Monoceros · Musca · Norma · Octans · Ophiuchus · Orion · Pavo · Pegasus · Perseus · Phoenix · Pictor · Pisces · Piscis Austrinus · Puppis · Pyxis · Reticulum · Sagittarius · Scorpius · Sculptor · Scutum · Serpens · Sextans · Taurus · Telescopium · Triangulum Australe · Tucana · Ursa Major · Ursa Minor · Vela · Virgo · Volans · Vulpecula • Throughout history different cultures have noticed and given meaning to constellations

Ursa Major (Big Dipper) • The Navajo (American Natives) describe Ursa Major as the Great Bear.

Ursa Minor (Little Dipper) • Commonly visualized as a baby bear with an unusually long tail (from being spun around the Earth)

Ursa Minor (Little Dipper) • Discovered by Claudius Ptolemaeus (Ptolemy) • At the end of the 'handle' lies Polaris (North Star)

Ursa Major and Ursa Minor • Artemis, the moon goddess and goddess of the hunt, always had hunting companions with her when she went on the hunt. One such companion was Callisto, a beautiful young maiden. One day Zeus passed by a woodland cove and spied the sleeping Callisto. Zeus disguised himself as Apollo and made Callisto his lover. They had a child named Arcas. Of course Zeus knew that both Hera, his wife, and Artemis would be angry with Callisto so to protect her he turned her into a bear to keep her hidden from Artemis and Hera. One day, Arcas was hunting and he came across a great bear. He was just about to shoot his arrow when Zeus intervened and changed him into a little bear so that Arcas could know who the great bear really was. Zeus then transported the two bears to the heavens so that they would be protected from the wrath of the angry goddesses. However, Hera was unhappy that Callisto and her son were shining so brightly in the heavens so she asked the ocean god to prevent them from ever bathing in the ocean waters. And so, according to this story, that is why the two bears are forced to circle the heavens while the other constellations are allowed to dip below the horizon and bathe in the immortal waters every night.

Polaris aka North Star aka Pole star • The brightest star in the Ursa Minor constellation • 430 light years from earth • Actually a multiple star system

The constellation of Orion (useful in finding other stars)

Sirius • The brightest star in Earth’s sky • Part of Canis Major (the dog star)