Chapter 2… The Sky. The Night Sky. People have studied the sky for thousands of years. Early humans organized the night sky by naming groups of stars called constellations .
This scale is known as apparent visual magnitude because the numbers describe how the stars look to a human observer on Earth.
IA / IB = (2.512) (mB – mA)
mA – mB = 2.512 Log (IB / IA)
1. Apparent path of the Sun in its yearly motion around the sky
2. Projection of Earth’s orbit on the sky
3. The plane of Earth’s orbit