Fast Facts

The Moon orbits the Earth approximately every 27¼ days. The Moon reflects sunlight onto the Earth. It is over a quarter of Earth's diameter, which is much larger in comparison to its planet than any other in the solar system.

However, despite its size, gravity on the Moon is about a sixth of that on the Earth. For example, an object weighing 100 pounds on the Earth would weight only 17 pounds on the Moon.

Because there is no atmosphere on the Moon, there are no weather systems. The lack of atmosphere also means there are large temperature swings from the sunlit side to the dark side. On the sunlit side, temperatures are as high as 250°F (>100°C), falling to as low as -250°F (-173°C) on the dark side.

## Overview

We observe the different angles between the Sun, Earth, and Moon by the phases of the Moon we see each month. Students, acting as the Earth, will see differences in light and dark sides of their hand-held moon.

TOTAL TIME 10 minutes Table lamp (or another light source) for class (A clear light bulb will work better than a frosted bulb). Per pair of students: pencil; white Styrofoam ball (approximately two to three inches in diameter). Observation form (pdf) A room that can be darkened. Rip Currents

### Procedure

1. Divide the students into pairs and distribute one observation form to each student.
2. Place a lamp on a table or desk and remove the shade. Turn the lamp on.
3. Stick the Styrofoam ball on the pencil.
4. Darken the room.
5. Have one student in each pair hold the pencil with the ball at arms length, blocking out the light from the lamp. Explain they represent the Earth, the ball is the Moon, and the lamp is the Sun.
6. On the observation form, under the "View from Earth" column, have that student draw/shade what their "moon" looks like, comparing the light and dark side of the ball. Have the student label this as "New Moon".
7. Have the other student mark the location of the Moon relative to the Earth and Sun on the dotted line (representing the Moon's orbit) under the "Position in Space" column.
8. Have the student holding the "Moon" rotate 45° counter-clockwise. Repeat steps 6 and 7. Label this as "Waxing Crescent".
9. Rotate another 45°. Repeat steps 6 and 7. Label this as "First Quarter".
10. Repeat steps 6 and 7 for each additional 45°, labeling them as "Waxing Gibbous", "Full Moon", "Waning Gibbous", "Last Quarter", and "Waning Crescent" respectfully.
11. Have the students switch positions and repeat the process again.

### Discussion

Each student will see their "moon" from two vantages points; from Earth and from "space". They should quickly observe the orbit of the Moon is the reason for the various phases of the moon.

They will also observe the phenomena of eclipses at New and Full Moon positions. At "New Moon", when the Moon is between the Earth and Sun, the Moon will block the Sun's light onto the Earth, called a solar eclipse. At "Full Moon", the Earth blocks light from reaching the moon. This is called a lunar eclipse.

Explain that since the Moon's orbit is inclined to the Earth's equator, that direct alignment of Earth, Moon, and Sun occurs typically only twice a year, six months apart. The remaining times, the Moon's orbit is positioned either above or below the shadow cast by the Earth.

Also, as the Moon orbits the Earth, its tidal pull also moves around the Earth. As a result, the times of high and low tides changes each day.

When the Moon, Earth and Sun are inline (twice a month), the tidal pull by the Moon and Sun are at their greatest, producing "Spring Tides", where the difference in height between the daily high and low tide are at their greatest.

When the Earth, Moon and Sun are at right angles to each other (also twice a month), the difference in height between the daily high and low tides are at their least, called "Neap Tides". The "Spring Tide or Neap Tide" wheel (above right) can be printed and cut-out to help illustrate how the orbit of the Moon affects the spring and neap tides.

Rip currents are powerful, channeled currents of water flowing away from shore at any beach with breaking waves, including the Great Lakes. They occur regardless of the tides, but low tide can enhance the intensity of the current, making them more dangerous.

Rip currents are the leading surf hazard for all beachgoers, particularly for weak or non-swimmers. While rip current speeds are typically 1-2 feet per second, speeds as high as 8 feet per second have been measured - that's faster than an Olympic swimmer! Thus, rip currents can sweep even the strongest swimmer out to sea.

Rip current safety:

• Learn how to swim.
• Never swim alone.
• Be cautious at all times, especially when swimming at unguarded beaches. If in doubt, don't go out!
• Whenever possible, swim at a lifeguard protected beach.
• Obey all instructions and orders from lifeguards.
• If caught in a rip current, remain calm to conserve energy and think clearly.
• Don't fight the current. Swim out of the current in a direction following the shoreline. When out of the current, swim towards shore.
• If you are unable to swim out of the rip current, float or calmly tread water. When out of the current, swim towards shore.
• If you are still unable to reach shore, draw attention to yourself: face the shore, wave your arms, and yell for help.
• If you see someone in trouble, get help from a lifeguard. If a lifeguard is not available, have someone call 9-1-1 . Throw the rip current victim something that floats and yell instructions on how to escape. Remember, many people drown while trying to save someone else from a rip current.

Fast Facts

The Moon orbits the Earth approximately every 27¼ days. The Moon reflects sunlight onto the Earth. It is over a quarter of Earth's diameter, which is much larger in comparison to its planet than any other in the solar system.

However, despite its size, gravity on the Moon is about a sixth of that on the Earth. For example, an object weighing 100 pounds on the Earth would weight only 17 pounds on the Moon.

Because there is no atmosphere on the Moon, there are no weather systems. The lack of atmosphere also means there are large temperature swings from the sunlit side to the dark side. On the sunlit side, temperatures are as high as 250°F (>100°C), falling to as low as -250°F (-173°C) on the dark side.