Notes: Ch.-2.1 Discovering the Universe for Yourself

What does the universe look like from Earth?

• With the naked eye, we can see more than 2,000 stars as well as the Milky Way.

Constellations: 

• is a region of the sky
• 88 constellations fill the entire sky! 

The brightest star in a constellation.....?

• C. May actually be quite far away from each other   

 The Celestial Sphere:

• stars at different distances all appear to lie on the celestial sphere
• the ecliptic is the Sun's apparent path
• the 88 official constellations cover the celestial sphere, but lie at different distances 
• (they're each like their own state)

The Local Sky

• An object's altitude (above horizon) and direction (along horizon) specify its location in your local sky.
• Horizon (altitude = 0°) - The boundary between Earth & sky.
• Meridian - An imaginary half-circle stretching from south horizon, through the zenith, to the north horizon. 
• (Azimuth: X° clockwise from north)
• Zenith (altitude = 90°) - The point directly overhead.
• Altitude = 60°

• WE MEASURE THE SKY USING ANGLES!
• The angular size of your finger at arms length is about 1°. How many arcseconds is this?
• C. 60 X 60