Warm –up • Where are the stars and constellations located? • Draw the earth on it’s axis • What is a sphere? • What is latitude and longitude • Are you good at following directions?
Night Sky Basics Section 1
The celestial sphere • The stars and planets appear to be on a large sphere surrounding the earth • NOT TRUE
Aligned with earth • Celestial equator along the same line as earth equator • Celestial north pole over north pool of earth
Earth Coordinate System vs. The Celestial Coordinate System • Pittsburgh is 42 degrees lat, by 85 degrees long
Latitude vs. Longitude • Measures the angle north or south of the equator • 0-90 north • 0- -90south • Equator is 0 degrees • Measures angle east or west • 0-180 East • 0-180 West • Prime Meridian is 0 Latitude Longitude
Declination vs. Right Ascension • Distance measured north/south • 0-90 north • 0-90 south • Latitude • Distance measured eastward on Celestial Sphere • 0-24 hours • Longitude Declination Right Ascension
Celestial Sphere Terminology • Zenith: Point that is directly overhead
Ecliptic • The apparent path that the sun takes around the celestial sphere
Polaris • The north star • Directly overhead • Appears not to move
Precession • The earth slowly wobbles on its axis of rotation. • One wobble takes approximately 26,000 years. • Because of this slow wobble, the stars SLOWLY move in a small circle in the night sky.
Star • A star is a massive, luminous ball of plasma that is held together by gravity.
Where is polaris? • North pole • Equator • Pittsburgh • At zenith • At horizon • 42 degrees
South star • THERE IS NOT A SOUTH STAR!
Warm-up • Draw a star • Draw a constellation: • Name a star:
Constellations • A constellation is an official grouping of stars. • They are usually ancient in origin, and come from greek mythology
Asterism • an unofficial grouping of stars that make a pattern in the sky. • will usually vary from region to region • Summer Triangle: Vega, Deneb, and Altair, • Big dipper • Piece of the constellations Ursa Major • In northern Europe, they call a part of ursa major the “Great plow”.
Circumpolar constellations • visible all year round • It appears to circle the celestial pole.
Finding Circumpolar constellations • Subtract your latitude from 90 • Pittsburgh: 42 • Florida: 30 • North Pole: 90 • Equator: 0
Circumpolar constellations in our area • 1. Ursa Major, • 2. Ursa Minor, • 3. Cassiopea, • 4. Cephius, • 5. Draco.
Constellation Names and Designations • Constellation Names: • Latin names. • Most of these names come from Greek mythology.
Star names • Arabic names. • Many star names come from Mid-Eastern mythology.
Star Designations • Stars in constellation are designated by their brightness. • astronomers use greek letters. • The brightest star is designated Alpha, The second brightest is designated Beta, the third brightest is designated Gamma, etc
Ursa Minor Polaris (The North Star)
Cassiopeia Polaris (The North Star)
Gemini Castor Pollux
Orion Betelgeuse Rigel
Canis Major Sirius
Canis Minor Procyon
Taurus Aldebaran Pleiades
Mythology • Ursa Major • In Greek mythology, Zeus (the king of the gods) lusts after a young woman named Callisto, a nymph of Artemis. Hera, Zeus's wife, transforms Callisto into a bear due to her jealousy of being extremely beautiful. Callisto, while in bear form later encounters her son Arcas. Arcas almost shoots the bear, but to avert the tragedy, Zeus hurls them both into the sky, forming Ursa Major.
Orion • One story tells that Orion was killed by a giant scorpion; the gods raised him and the Scorpion to the skies,
Aquila • Aquila was identified as ΑετόςΔίας (Aetos Dios), the eagle that carried the thunderbolts of Zeus and was sent by him to carry the shepherd boy Ganymede, whom he desired, to Mount Olympus;