Earth
It takes this long for the moon to revolve completely around the Earth.
What is 29.5 days or about a month?
This keeps the Earth and moon in their orbits.
What is "gravity"?
The moon affects this part of the Earth, changing it daily on our beaches.
What are tides.
This occurs when the moon is furthest from the Sun in its orbit, which causes the moon to appear smaller and unable to completely cover the Sun. During this event an outer ring of light from the Sun is visible.
What is the "annular Eclipse"?