All bodies in the solar system are in constant motion. Day vs. Night
The Earth rotates on its axis as it revolves around the Sun. It takes approximately 24 hours, a day, for a complete rotation to occur. This counterclockwise motion occurs from west to east, causing the Sun to appear to rise in the east and set in the west.
Year
While the Earth rotates on its axis, it is also revolving around the Sun. It takes 365 ¼ days, a year, for this motion/orbit to occur.
The Earth revolves around the Sun in an elliptical orbit.
Lunar (Moon) Movement
The Moon rotates on its axis and revolves around the Earth as the Earth revolves around the Sun.
It takes about 27 Earth days for the Moon to rotate on its axis and about 29 ½ Earth days (month) for it to revolve around the Earth.
Because the Moon’s period (time)of rotation on its axis and period of revolution around the Earth are nearly the same, the same side of the Moon always faces Earth.
Changes in the Moon’s position as it revolves around the Earth results in more or less of the sunlight reflected form the Moon being visible when observing the Moon from the Earth. This causes the Moon to appear to change shape.
Eclipses
Eclipses occur when an object in space passes directly between two other objects or between the object and the viewer.
A solar eclipse occurs when the Moon passes directly between the Sun and Earth, blocking the Sun’s light and casting a shadow over a certain area on Earth. This can only occur during a New Moon.
A lunar eclipse occurs when Earth passes directly between the Sun and the Moon, blocking the Sun’s light so that Earth’s shadow hits the Moon casting a shadow over the Moon. This can only occur during a Full Moon.
An eclipse does not occur at every New Moon and Full Moon because of the angle of the Moon’s orbit around the Earth.
REVIEW QUESTIONS
What causes lunar phases? Moon phases are caused by the Moon’s position around Earth and Earth’s position around the Sun.
How do the Sun, Moon, and Earth work together to cause solar and lunar eclipses? Solar eclipses occur when the Moon aligns between Earth and the Sun, creating a shadow on Earth. Lunar eclipses occur when the Earth aligns between the Sun and Moon, creating a shadow on the Moon.
What is a Total Solar Eclipse? •When the moon blocks out the Sun entirely
What is a Partial Solar Eclipse? •When the moon blocks out a portion of the Sun
What is a Total Lunar Eclipse? •Occurs when the moon completely passes into the darkest part (umbra) of Earth’s shadow •Only occurs during full moon phase •Occurs at night What is a Partial Lunar Eclipse? •Occurs when the moon passes into the lightest part (penumbra) of Earth’s shadow. •Occurs only at Full moon phase •Occurs at night