Gravity Rules!
What force keeps planets in orbit around the Sun?
Gravity
What causes day and night?
Earth’s rotation on its axis.
What causes the seasons on Earth?
Earth’s tilt and its revolution around the Sun.
How long does it take the Moon to orbit Earth?
About 27.3 days
What causes tides on Earth?
The gravitational pull of the Moon (and the Sun).
Why do objects fall toward Earth instead of floating away?
Earth’s gravity pulls them toward its center.
How long does it take Earth to complete one rotation?
24 hours
When the Northern Hemisphere is tilted toward the Sun, what season is it?
Summer
What causes the Moon’s phases?
The changing positions of the Moon, Earth, and Sun.
When do the highest high tides occur?
During full and new moons (spring tides).
If you travel to the Moon, your weight changes but your mass stays the same. Why?
Gravity is weaker on the Moon, but mass doesn’t depend on gravity.
Why do we experience sunrise and sunset?
As Earth rotates, different parts face toward or away from the Sun.
How is sunlight different in winter vs. summer?
In winter, sunlight hits at a lower angle and is less direct.
Which phase comes right after a new moon?
Waxing crescent
What is a solar eclipse?
The Moon passes between Earth and the Sun, blocking sunlight.
How does gravity affect tides on Earth?
The Moon’s gravitational pull causes ocean tides.
If Earth rotated more slowly, what would happen to the length of a day?
The day would be longer.
What would happen if Earth were not tilted on its axis?
There would be no seasons.
Why do we always see the same side of the Moon?
The Moon rotates once per orbit (synchronous rotation).
What is a lunar eclipse?
Earth’s shadow falls on the Moon.
What would happen to planets if the Sun’s gravity disappeared?
They would move in straight lines off into space.
Why does the Sun appear to move across the sky?
Because Earth rotates from west to east.
Why are seasons opposite in the Northern and Southern Hemispheres?
When one hemisphere is tilted toward the Sun, the other is tilted away.
What phase occurs when the Moon is completely illuminated?
Full moon
Why don’t eclipses happen every month?
The Moon’s orbit is tilted about 5° relative to Earth’s orbit.