physics (the moon)

Observing the sky:

• a sidereal day is the time takem for the eath to spin once.
• if you looked at the night sky for long enough you'd see distance stars appear to cross the sky from east to west.
• astronomers have known for years that its not the stars that move, but the earth that spins on its axis. 
• a sidereal day is the time taken for a star to return to the same position in the sky. its about 23hrs and 56 minutes.

the sun and moon appear to cross the sky at different speeds.

• its not the stars- the sun and moon also appear to cross the sky from east to west.
• the sun seems to move more slowly across the sky than distance stars-it takes 24 hours to get to the same…