Earth, Moon, and Sun – Study Guide
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Season occurs on Earth because the axis is tilted (not because we are closer or farther away
from the sun)
More direct sunlight will result in a warmer season (spring, summer). Less direct sunlight will
result in a colder season (autumn, winter).
Areas near the equator do not experience much change in the amount of sunlight energy they
receive during the year, therefore they do not have the same seasonal changes as we do.
The seasons are opposite in the northern and southern hemisphere.
1 rotation on the axis = 1 day on Earth
1 revolution around the Sun= 1 year on Earth
Earth’s rotation around the axis is responsible for day and night.
Earth’s axis is tilted at an angle of 23.5 degrees.
Daylight hours are longer for the hemisphere tilted towards the Sun.
An equinox is a day where every place on Earth receives 12 hours of daylight. These occur on or
around March 21 and Sept 21.
A solstice is either the longest or shortest day of the year. These occur on or around Dec 21 and
June 21.
Earth’s orbit (revolution) around the Sun is elliptical (a flattened circle), meaning we are closer
to the Sun during our winter in the northern hemisphere. Our distance from the Sun DOES NOT
affect our seasons.
New moon occurs when the Moon moves between the Earth and Sun.
A solar eclipse can occur during a new moon. A solar eclipse is caused by the moon blocking
sunlight from reaching the Earth. Solar eclipses can be partial or full.
½ of the moon’s surface is always in sunlight (no matter what phase we see)
During a full moon the Earth is between the Sun and Moon. We see the entire lit ½ of the moon.
A lunar eclipse can occur only during a full moon. The Earth’s shadow falls on the moon during a
lunar eclipse.
Waxing means the moon is becoming more full, Waning means the moon is becoming less full.
When the moon is at a right angle to the Earth and Sun we see a quarter moon phase (we can
view ½ of the sunlit ½ ) ( ½ of ½ is ¼).
The Moon and Sun appear the same size in our sky. The Sun is actually much, much larger than
the Moon but it is also much farther away.
The textures we see on the moon are maria (old lava plains) and impact craters (areas where
something struck the moon and left a depression).