La Luna, My Moon and its Phases

The moon, it is always there in the sky watching us. Its no wonder that stories have been weaved through our history that tell of the mystical powers of the moon. One of the oldest depictions of the of the moon is located not too far from here in Knowth. The central chamber of the burial mound is said to hold this nearly 5000 year old map of the moons surface. Those who have seen it say that it has pits and mountains representing the craters and mountains we can see on the moon with the naked eye. The rest of the burial mound is decorated with circular and spiral patterns, all believed to be various depictions of the moon.

The truth is however, that the moon is no more mystical then any rock in the forest. The moon isn’t like all the twinkling stars in the sky, it doesn’t shine bright, in fact it doesn’t shine at all. I’m not trying to say that the moon isn’t important to our everyday lives, it is responsible for the ocean tides, changing day lengths and the magnificent eclipses that make us stop in our tracks.

You might wonder how the moon was created, of course no one knows for sure. There are theories that it was created at the same time as the Earth as just extra material that was spun out of Earth’s gravitational field. However, the most widely accepted theory is that there was a massive impact from an object the size of Mars while the Earth was still forming. This impact threw debris into space, and as the Earth reformed the remaining material collected into what we know as the moon.

Did you know that we always see the same side of the moon? The moon’s rotational period, or lunar day, is exactly the same as the lunar orbital period, or the time it takes to go around the Earth once. The Moon is in a geosynchronous orbit meaning it is locked in the same orientation with the Earth.

The moon is the brightest object in the sky, second only to the sun, however if it weren’t for the sun we wouldn’t be able to see it at all. The surface of the moon is actually very dark and it doesn’t produce any of its own light. The dust on the moons surface is very similar in color to coal, however even this dark dust can reflect a small amount of light. The moon reflects most of its light directly back towards the sun. This reflection towards the sun is what causes phases of the moon. As the moon orbits around the Earth, the angle of the sun to the moon to the Earth changes. In the diagram below you can see all the phases of the moon.

There are two types of eclipses, solar and lunar. Lunar eclipses happen when the Earth’s shadow blocks the light from the sun during its full moon phase. Since the shadow of the Earth is larger than the viewing disk of the moon, the whole moon goes dark. A solar eclipse happens when the Moon passes into the path of the suns light to the Earth during the new moon phase. The Moons shadow is much smaller then light coming from the sun, so thats why a solar eclipse has a specific viewing area across the Earth’s surface.

Long ago, Chinese people used to think that solar eclipse was a dragon swallowing the sun. They would make noise by banging on drums and yelling to try and scare the dragon away. Of course solar eclipses are only temporary, so the sun would always return.

Want to create your own eclipse?

Materials:

tennis ball, ping pong ball, flashlight and a table with a table cloth

Procedure:

  1. Place the tennis ball about two feet away from the flashlight, and the ping pong ball in between at about the one foot point. 
  2. Make the room dark.
  3. Turn the flashlight on  and make sure its pointed at the tennis ball.
  4. Move the ping pong ball around and observe where the shadow falls.
  5. The tennis ball represents Earth, the ping pong ball represents the Moon, and the flashlight is the Sun.
  6. What happens when you place the Moon on the other side of the Earth?
  7. If you would like to observe the phases of the moon for yourself, slowly move the ping pong ball in a circle around the tennis ball and observe how the light from the flashlight looks on it.

Invisible Ink Three Ways

Have you ever wanted to send a secret message to a friend? Its easier then you think! To others the paper looks completely blank, but with the right tricks, you can write and read invisible ink!

The Milky Way

Materials:

bowl, milk, q-tip, paper, 100-watt lamp

Procedure:

  1. Put a little milk in a small bowl.
  2. Write with the milk on a piece of paper with a Q-tip or a brush.
  3. Let your message dry completely.
  4. To read the message just heat the paper. Use an iron or 100-watt light bulb or stove element. Don’t rest the paper on the bulb. Ask an adult to help in case a fire starts and never use a halogen light.

Explanation:

Milk is an organic product which means it comes from a living thing. When it’s heated, it burns at a slower rate than the paper. Your invisible message shows up brown.

The Lemony Way

Materials:

bowl, milk, q-tip, paper, 100-watt lamp, salt, wax crayon

Procedure:

This works the same way as the milk method.

  1. Simply dab a Q-tip or brush into a bowl of lemon juice and write away. Just make sure you don’t use too much.
  2. To see the message, simply heat the paper after it dries.
  3. Another way to see the message is put salt on the drying ink.
  4. Give it a minute and then wipe the salt off.
  5. Use a wax crayon to color over the message.

Explanation:

Both lemon juice and milk are mildly acidic and acid weakens paper. The acid remains in the paper after the juice or milk has dried. When the paper is held near heat the acidic parts of the paper burn or turn brown before the rest of the paper does.

 

The Baking Soda Way

Materials:

Baking Soda, water, Q-tip, grape juice, sponge

Procedure:

  1. Mix about 1/4 cup of baking soda and 1/4 cup of water.
  2. Next, write using a Q-tip or paintbrush on a piece of paper.
  3. Let it dry completely.
  4. To read the secret message, submerge paper in a shallow pan of grape or cranberry concentrate. Don’t forget – juice concentrate can stain.

Explanation:

Grape juice has an acid that reacts with the baking soda. A different color appears wherever the secret message is written.

Spinning to Make Colors

Science of Art: Spinning to Make Colors

Materials:

Pencil, compass (or cookie cutter), White Card stock, scissors, markers or crayons, sharp pencil or wooden skewer

Procedure:

  1. Use a pencil and a compass or a circle cookie cutter to make circle shapes on white card stock. Cut them out with scissors.
  2. Divide the circles into equal sections and decorate each section with different colors.
  3. Push a sharp pencil or stick through a hole in the center of each circle.
  4. Spin the spinner as fast as you can on a tabletop and watch the different colors merge. If you color a spinner with the colors of a rainbow, it may appear white when you spin it.

Result:

The spinner is turning so fast that instead of seeing separate colors, our eyes see the mixture.

Explanation:

White light is made up of the colors of the rainbow, so a spinner decorated with these colors appears white. Look closely at a color TV or the photographs in a book. The pictures are made up of lots of tiny colored dots. By seeing books and tvs from a distance, the dots seems to mix together and make colors.

 

Why is the Sky Blue?

Have you ever looked up at the sky and wondered why its blue during the day yet black at night? The explanation is simple and it also explains the beauty of sunsets and sunrise.

Materials:

Flashlight, drinking glass, eye dropper, water, milk, spoon

Procedure:

  1. Fill glass with water
  2. In a darkened room, direct the flashlight through the side of the glass and through the water.
  3. Observe the color of the water
  4. Add 1 drop of milk to the water and stir.
  5. Again shine the light through the water.
  6. Observe the color of the water.

Result:

The light passes through the clear water, however the milky water has a light blue-ish tint.

Explanation:

The waves of color that make up white light are actually many different sizes (wavelengths). The particles of milk the the water are small enough to block and reflect the blue light waves. Those waves are bounced around and cause the predominant light that we see coming from the milky water. Nitrogen and oxygen in the Earth’s atmosphere, are also small enough to separate out the blue light waves from sunlight. The blue light scatters throughout the entire atmosphere making the sky look blue from the ground, and the Earth look blue from space.

The color in the milky glass isn’t perfectly blue because milk contains molecules of several different sizes, and larger molecules are also reflecting light. This same phenomena happens in the atmosphere when large amounts of dust and water vapor scatter more then just the blue light waves. Clean, dry air, free of dust and water vapor, scatters the most blue waves.

Making White Light

Science of Art: Making White Light

Materials:

3 flashlights, red, green and blue cellophane or theater films, and a white background

Procedure:

  1. Color three flashlights with red, green, and blue cellophane.
  2. Shine them onto white paper or onto the white floor/wall.
  3. Allow the lights to overlap. See how many new colors you can make. Can you ever make white?

Result and Explanation:

You will quickly notice that whenever all three colors overlap, a white spot forms! White is made from all of the colors of the rainbow, and since Red, Green and Blue contain all of the primary colors, you see white. When colors mix they make different colors. Colors on a computer are generally some combination of red, green, and blue color mixtures.

Separate Colors with Water

Science of Art: Separating Colors

Materials:

paper towels, scissors, colored markers, water, jar

Procedure:

  1. With a pair of compasses draw some circles onto paper towels(or you can use a round cookie cutter). Cut them out with scissors.
  2. Using markers of different colors (black, purple, green, brown and orange are good colors to use) to draw a dot (about the size of a dime) of color in the middle of each circle.
  3. Place each circle of paper towel over the top of a clean dry jar.
  4. Add drops of water to the dot of color, use an eye dropper or a straw.
  5. Allow the color to spread and dry.

Result:

Rings of different colors will appear.

Explanation:

You will see that as the water spreads the colors will travel at different speeds and you will see that each color will create a ring. In printing and painting there are three primary colors – red, blue, and yellow. The enormous variety of colored dyes, paints, and inks are made by mixing different amounts of two or more of the primary colors.

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