Transcript Finding Your Way In The Sky

Finding Your Way In The Sky
The Big
Dipper
Directions in the Sky
•
•
•
•
•
North is toward the North Celestial Pole
South is toward the South Celestial Pole
East is toward East on the ground (usually)
West is toward West on the ground (usually)
On a ground map you’re outside a sphere looking
in.
• On sky maps you’re inside a sphere looking out.
• East and West on star maps are reversed
compared to maps of the ground
Directions in the Sky
Directions Near The Pole
Stars and Constellations
• Many proper star names are Arabic
• Catalog labels also used (Alpha Centauri)
• Constellation names are Latin
– Ancient groups from Near Eastern myths via
Greeks
– Numerous 17th-18th Century inventions
• 89 Constellations
– Fixed boundaries in sky
– Every star is in one, and only one, constellation
• There is no “official” way to draw constellations
About Constellation Names
• Latin uses word endings where we often use
prepositions (Compare English ‘s)
• Possessive form different from normal form
• Centaurus but Alpha Centauri
• Andromeda but Alpha Andromedae
• Gemini – Geminorum
• Virgo – Virginis
• Orion – Orionis
• Ursa Major – Ursae Majoris
Recognizing Constellations
•
•
•
•
They change location
They change times they are visible
They change orientation
Best strategy: Learn shapes and relative
locations
• Different books use slightly different figures.
Use whatever works for you
Stars Vary in Brightness and Color
•
•
•
•
•
•
•
1st Magnitude = Very Bright
2nd Magnitude = Polaris, Big Dipper
3rd Magnitude = Fairly obvious
4th Magnitude = Moderately Faint
5th Magnitude = Faint
6th Magnitude = Barely visible
Colors range from reddish through yellow to
white and blue-white. Colors are subtle
Some
Stars
Never
Rise or
Set
North Polar Constellations
The Late Summer Sky
The Autumn Sky
The Andromeda Myth
The Andromeda Myth
The Andromeda Myth
The Andromeda Myth
The Andromeda Myth
The Andromeda Myth
The Andromeda Myth
The Autumn Sky
Winter Sky at Twilight
The Winter Sky
The Springtime Sky
Early Summer Constellations
Some Southern Stars
The Southern Cross
The Southern Cross
Southern Cross and Centaurus
Southern Cross and Centaurus