Gravity and Motion
What force pulls objects toward each other and keeps planets in orbit?
Gravity
How long does it take Earth to revolve around the Sun?
What causes the Moon to appear to have phases?
The Moon’s revolution around Earth and the way sunlight hits it.
What is the Sun?
A star
What causes shadows?
An object blocking light
What is the path an object takes around another object called?
An orbit
What two factors cause the seasons?
How long does one full cycle of moon phases take?
About 1 month (about 30 days)
What are two reasons a star may look brighter from Earth?
Its size and its distance from Earth
When are shadows the shortest during the day?
At noon, when the Sun is highest
How long does it take Earth to rotate once on its axis?
24 hours
What is the Sun’s role in the solar system?
It is the only star and the center of our solar system.
What are the two main types of tides?
High tide and low tide
Why do stars appear to move across the night sky?
Because Earth rotates
Why are shadows long in the morning and afternoon?
The Sun is low in the sky
What causes day and night on Earth?
Earth's rotation
Why does the amount of daylight change throughout the year?
Because of Earth’s tilt and its revolution around the Sun.
What causes tides on Earth?
The Moon’s gravity (and the Sun’s to a lesser degree)
Which galaxy do we live in?
The Milky Way
Why do seasons change?
Earth’s tilt + its revolution change how much sunlight each hemisphere gets
Why does the Moon always show the same side to Earth?
It rotates and revolves at the same rate (about 30 days)
Why does the Sun appear to move across the sky each day?
Because Earth rotates on its axis.
During which tides are the high tides the highest and low tides the lowest?
Spring tides
Which is larger—a galaxy or a solar system?
A galaxy
Why are days longer in summer and shorter in winter?
The tilt of Earth causes some areas to receive more or less sunlight during its revolution