Study Guide Astronomy
Science Units 1-4
Know the definitions of the following terms.
Revolution: ___The movement of an object around another object. ______
Rotation: Movement of an object as it spins on it’s axis Earth’s rotation= 1 day 24 hours
Ecliptic: apparent path of the sun as it appears to move across the sky
Equinox: the time of the year when there is equal day and night
Anasazi: Ancient people from the southwest US that created their own calendar based on the movement of the sun
Be able to explain…
Why we have seasons?
· We have seasons because of the tilt of the earth. At different times during the year the Earth is tilted towards the sun and away from the sun.
· If it’s summer in the Northern hemisphere it is winter in the Southern hemisphere.
Why the sun and moon look like they are the same size from earth?
The sun is 400 times larger than the moon but the moon is also 400 times closer to Earth
How shadows are different in the winter and the summer?
Winter shadows are longer and the sun’s path appears to stay closer to the horizon. Summer shadows are shorter and the sun’s path appears higher in the sky.
How big is the earth compared to the sun?
The sun is 109 times the size of Earth.
How big is the moon compared to the earth?
The moon is ¼ the size of Earth or the Earth is 4 times larger than the moon.
How far away is the moon from earth?
The moon is 30 Earth diameters away from the Earth.
How does the sun appear to move across the Earth’s sky?
Due to the counterclockwise rotation of the Earth, the sun appears to move from east to west as it rises and sets each day
Why is the North Star important?
The North star is the closest star to the North Pole. It provides a stable marker in the Northern Hemisphere for which direction is North.
Which seasons have an equinox?
Spring- March 21st and Autumnal (Fall) September 21st
When shadows are long and when they are short?
· Shadows are longer at dusk and at dawn. They are also longer when the sun is closer to Earth’s horizon.
· Shadow are shorter at solar noon and when the sun is higher in the sky.
What did ancient people believe about the sun?
Ancient people believed that the Earth was in the center of the universe. They thought the sun revolved around the Earth.