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.
tennis ball, ping pong ball, flashlight and a table with a table cloth
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!
bowl, milk, q-tip, paper, 100-watt lamp
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.
bowl, milk, q-tip, paper, 100-watt lamp, salt, wax crayon
This works the same way as the milk method.
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.
Baking Soda, water, Q-tip, grape juice, sponge
Grape juice has an acid that reacts with the baking soda. A different color appears wherever the secret message is written.
Pencil, compass (or cookie cutter), White Card stock, scissors, markers or crayons, sharp pencil or wooden skewer
The spinner is turning so fast that instead of seeing separate colors, our eyes see the mixture.
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.
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.
Flashlight, drinking glass, eye dropper, water, milk, spoon
The light passes through the clear water, however the milky water has a light blue-ish tint.
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.]]>
3 flashlights, red, green and blue cellophane or theater films, and a white background
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.]]>
paper towels, scissors, colored markers, water, jar
Rings of different colors will appear.
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.]]>
Homemade spectra scope, element lamps, markers and worksheet.
We are looking at the emission lines of spectra. When excited, elements emit light in different parts of the light spectrum, including visible light. This is how astronomers figure out what distant objects are made of – every atom and molecule has its own unique fingerprint, and based on the brightness of the “fingerprint”, we can even tell how much of an atom or molecule is present based on the brightness of the lines. Compare the lamps to what you see when you look at the sky through the spectra scope.]]>
I’ve been away for the last couple weeks, but I haven’t been sitting around doing nothing. I’ve been incredibly busy officially introducing myself to the world. Back in May I was asked by Onizumi Hartstein to help design a children’s programming track for an internet creators convention that she started in 2010, Intervention. I was all too willing to help out and agreed to take point on several science experiment sessions specifically designed for kids aged 4-12.
This year was the first year for a children’s programming track at Intervention, so there were no rules or expectations. We planned a number of crafts, contests, dance parties, games and experiments for kids.
Since this convention focused on internet creators, there was a large focus on web comics and their fan base. I decided to focus one of my experiment sessions on the science of art. I taught the kids to experiment with light and color. We taught them how colors are created on TV or computer screens, how colors are combined to create other colors, how to separate colors, the colors of elements and we played with LEDs.
I decided to turn our participants into spies for the second experiment session. They were able to learn about fingerprinting, using invisible ink and decoding messages. The kids seemed to really enjoy the experiments and each one of them seemed to learn something they didn’t already know.
Of course we had to end with a little bit of fun! We decided to let the kids get a bit messy and play with explosions. We taught them about the reactions between diet cola and Mentos, water and Alka Seltzer, and we had a foam fight with baking soda and vinegar. All in all a huge success!
I’ll be sharing all of the experiments over the next few days. So get ready to have fun with
I needed to know how big the quake was and I was curious how far it could be felt. After a little searching I found it, a older model of a seismometer designed by James Forbes in 1844. It consisted of an inverted pendulum made from a stiff wire with a movable mass that allowed for the period to be altered. By placing a pencil on the end of the wire I could record the exaggerated movements of the free weight on a paper lined sphere. Here is a sketch of it:
Turns out the quake was about a 5.3 on the Richter scale, a moderate quake around the world, but pretty large here in the British Isles. By this morning the news had already been spread of the quake, and it seems that it was felt from Galway to Glasgow to London. The heaviest of the motion seems to have been felt in Caernarfon, Wales.
Materials: scissors, shoebox with a lid, a heavy weight, masking tape, a pencil with an eraser, a weight for the pencil like nails or washers, playdoh or clay, two paper clips, string and 2(or more) sheets of paper.
Place a paper strip against the box (below the slit you made in the lid) and slowly pull the strip forward.
Have someone else bump and shake the table as you pull the paper strips under the dragging pencil marker.
Compare the separate strips of paper.
When faults slip during earthquakes, they release energy in the form of a seismic wave. Seismographs capture and record the jolts and shakes from each passing wave. Seismograms (the graph made by a seismograph) are like earthquake fingerprints. Each tells an individual story of an earthquake: how deep it was, which direction the fault moved, and what kinds of rocks the waves passed through.
The strength of an earthquake is determined by the height of the energy waves that are recorded. Seismologists, scientists that study earthquakes, are able to determine when and where the quake happened by determining the times the waves arrive to different locations.
If you think of a fault like a patchwork quilt, each individual patch will have its own energy signature, and that signature will change depending on what direction each patch is moving. So if you think of a large earthquake like causing ripples in a patchwork quilt, you can see how there would be a huge number of overlapping signatures that have to be decoded by seismologists in order to figure out the exact location and cause of an earthquake.
Check out this USGS PDF for a series of 10 articles specifically designed to teach kids about Earthquake science.]]>
I saw a small group of children run past, all playing with various toys, dolls and cars, that they had obviously just gotten from the toy store down the block. They all seemed so excited about their newest acquisitions, except for one little boy. He had a small dim lantern that he kept trying to crank as he ran, he was unsuccessful at his attempt to multi-task. The dynamo generator required too much patience for this young man, I understood that impatience. I used to be that way, to excited about every new gadget to wait for it to charge up and work.
I called the boy over to me. I don’t know if he recognized me, or if he just respected me because of my clean boots and clothes. I asked him if he wanted to have a lantern that would work without the incessant cranking. He nodded in enthusiastic agreement. I asked him to fetch me a fresh lemon, and gave him some coins to pay for it. Off he ran to the vendor down the road. I sat myself down on the curb and pulled a handful of copper and silver coins out of a hip pouch. The boy returned and I pulled out my boot knife and cut the juicy lemon in half. I asked a few passerby’s for cigarette papers, and they all obliged. I squeezed the juice out of the lemon and soaked the papers in the juice. I quickly stacked the copper and silver coins with a lemon soaked paper in between each. I attached the new “wet cell” to the bulb from the lantern and it flickered to life.
The light was dim, but was enough to amaze. The look on the boy’s face was priceless, it was the look that made me chose this life. That astonishment was worth everything. I handed the boy the lantern and told him when the light went out to replace the lemon juice soaked papers to make the light shine once again.
What is really happening?
You have made yourself a “wet-cell”. This is a very basic form of the batteries that we use everyday, and was first discovered by Alessandro Volta nearly 200 years ago. The lemon juice is an acidic solution that easily conducts electricity. By placing the coins next to each other you are encouraging the sharing of electrons between the metals, and the lemon juice facilitates this exchange, and you end up with a flow of electricity.
Batteries that we use today are normally made from two or more “dry cells”. In each dry cell cell, there are 32 metals (a carbon rod contained by zinc) separated by blotting paper soaked in a very strong acid.