What causes the periodic change between night and day?
Earth's rotation
What is the summer caused by?
direct sunlight striking Earth
Why are there seasons?
Earth's axis is tilted.
What is the winter caused by?
indirect sunlight striking Earth
How would life on Earth be different if its axis was not tilted with respect to its orbit?
There would be no seasons.
During which season is the sun lowest in the sky?
winter
What causes the alternating pattern of night and day?
Earth’s rotation
What is the shortest day of the year?
winter solstice
What is the longest day of the year?
summer solstice
The big bang theory states that the universe is approximately _________.
14 billion years old
Because the universe is expanding, what happens to light from other galaxies as it reaches Earth?
It is red shifted.
Which statement tells a result of the big bang?
Galaxies are moving farther away.
How do scientists know that the universe is expanding?
The Doppler effect shows stars with red shifted light.
What is a cloud of dust and gas in space known as?
a nebula
Which pair of elements primarily make up a nebula?
hydrogen and helium
What did the solar system form from?
clouds of dust and gas
The word elliptical refers to which type of shape?
oval
During which season is the sun highest in the sky?
summer
Alpha Centuri is 4 light years from Earth.
How long would it take for light from Alpha Centuri to reach Earth?
4 Earth years
What is a light year is equal to?
5,866,000,000,000 miles
What happens to the force of gravity between two masses if they are moved closer?
It increases.
What happens to the force of gravity between two masses if they are moved farther apart?
It decreases.
Which choice states the planet or planets that have an elliptical orbit around the sun?
Earth, Jupiter, and Mars
What separates Mars from Jupiter?
asteroid belt
Which factor causes the seasons?
the tilt of Earth's axis with respect to the sun