Moon & Earth Cycles

3.8 The student will investigate and understand basic patterns and cycles occurring in nature. Specifically, patterns of natural events, day and night, seasonal changes, phases of the moon, and tides.

*Created by Emily Hooker

Key Concepts Include:

Some events in nature, such as the seasons, day and night, phases of the moon, tides, and life cycles, occur in a pattern or cycle.

The relationships that exist between and among the Earth, sun, and moon result in day and night, seasonal changes, phases of the moon, and the tides.

Earth’s rotation causes day and night.

The sun’s rays striking Earth at various angles causes our seasons.

Ocean Tides…

The moon orbits around Earth. The moon’s gravity pulls at Earth’s oceans and makes the water a little bit higher in some places, which in turn makes the water a little lower in other places. This phenomenon produces tides. Tides are daily changes in the elevation of the waters on our planet caused by the gravity of the moon and the sun.

A tide table is a chart used to map the times that the tides are going to be at.

Use the tide table on the previous slide to fill in this tide card. Choose one tide to use to answer the questions.

Think about tides…

How many high tides usually occur in one day? (2) How many low tides usually occur in one day? (2) About how much time passes between one high tide and the

following low tide? (6 hours) Would you describe tides as occurring in a cycle that follows a

natural pattern? Why, or why not? (Yes, tides occur in a pattern; a high tide is always followed by a low tide and they are approximately six hours apart.)

Keep thinking!

Name some other cycles or patterns found in nature. (moon phases, seasons, birds flying south for the winter and north for the summer, day and night)

Who might need to know where to find and how to read tide tables. (beach vacationers, fishermen, lighthouse keepers, lifeguards, boaters, swimmers, and surfers —anyone who works or lives near coastal waters)

Phases of the Moon…

The moon generates no light of its own. It shines because it reflects the light coming from the sun. Though it does not always appear so from Earth, half of the moon is always illuminated; that is, the sun always shines on one side of the moon, while the other side in darkness. However, as the moon orbits (revolves around) Earth, its position in relation to the Earth and the sun changes, and more or less of the illuminated side can be seen from Earth. These different views of the illuminated portions of the moon are called “phases of the moon.”

Take a closer look.

New Moon - The Moon's un-illuminated side is facing the Earth. The Moon is not visible (except during a solar eclipse).

Waxing Crescent - The Moon appears to be partly but less than one-half illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing.

First Quarter - One-half of the Moon appears to be illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing.

Waxing Gibbous - The Moon appears to be more than one-half but not fully illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is increasing.

Full Moon - The Moon's illuminated side is facing the Earth. The Moon appears to be completely illuminated by direct sunlight.

Waning Gibbous - The Moon appears to be more than one-half but not fully illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing.

Last Quarter - One-half of the Moon appears to be illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing.

Waning Crescent - The Moon appears to be partly but less than one-half illuminated by direct sunlight. The fraction of the Moon's disk that is illuminated is decreasing.

Following waning crescent is New Moon, beginning a repetition of the complete phase cycle of 29.5 days average duration. The time in days counted from the time of New Moon is called the Moon's "age". Each complete cycle of phases is called a "lunation” or lunar cycle.

Waxing cresent

First Quarter

Waxing gibbous

Full Moon

Waning gibbous

Last quarter

Waning cresent

New moon

Show what you know!