When Krakatoa erupted in 1883, the explosion and resulting tsunamis killed around 40,000 people, forever changed the geography of the East Indies, spewed tons of sulfur dioxide and ash into the atmosphere, and resulted in some of the most spectacular sunsets in recorded history. Artists and writers around the world tried to capture the blazing sky on paper, and some speculate that the psychedelic sky in Edvard Munch’s “The Scream” was inspired by a Krakatoa sunset.
Why are sunsets red? And how would volcanic ash make them even redder?
The colors we see depend on the light waves that are reflected and absorbed by the things around us. For example, grass looks green since it absorbs most of the visible light waves except green, reflecting that color back at our eyes. Things that look black absorb all the colored light waves. Blue light has a short wavelength, and easily bounces off surrounding particles (called scattering), while red light has a longer wavelength and is more difficult to scatter.
The oxygen and nitrogen that make up most of our atmosphere are good at filtering out blue and violet light, but your eyes are good at seeing blue light and sunlight doesn’t have to travel though much atmosphere when it’s directly overhead, so the sky looks blue on a sunny day.
As the sun sets, its light has to travel a longer distance across the atmosphere to reach your eyes. By the time we see it, many of the blue light particles have been filtered out, allowing you to see the red, yellow and orange light waves that remain. In addition, the lower atmosphere contains more large particles like dust and pollen, which scientists call aerosols. These particles scatter the blue light even more, allowing you to enjoy the red, yellow and orange light waves that remain to create a beautiful sunset.
The ash from Krakatoa was a very effective blue light filter, making the skies so red that fire engines were called out in New York.
To see how particles scatter light, fill a plastic container with water and shine a flashlight through it on to a white piece of paper. The light should look white.
Now add a few drops of milk to the water and shine your light through again. Does the color change? What if you add more milk or use a longer container, so the light has to travel farther?
What happened? Imagine that your flashlight is the sun and the milky water is the lower atmosphere. The molecules in milk are filtering out the blue light in your flashlight beam, allowing you to create your own red “sunset.”
We played around with dish soap this weekend to watch the Kaye effect, which I learned about from my physicist friend Dr. SkySkull.
It’s an experiment in liquid dynamics, and I’ll post a protocol (recipe) for how to do it in the next day or two.
I just put together a homemade science kit (for a silent auction at a fundraiser) and it was so cute I had to post a picture.
Click here to see a post with links to homemade science kit experiments. Love giving these as birthday and holiday gifts too! To take it up a notch, pair your science kit with KidScience app for iPhones/iPods!
Over the next few weeks, I’ll be posting some fun biology experiments, so be sure to check back in!
One of our favorite stops at the Minnesota State Fair is the Department of Natural Resources (DNR) building. After checking out some birds of prey, the fish pond and some monarch caterpillars, we stumbled on an entire room devoted to educating the public on the control of invasive species. Although I was familiar with buckthorn and Zebra Mussels, it was surprising to see the lowly earthworm represented alongside other more obvious dangers to Minnesota’s ecosystems.
We learned that the earthworms in Minnesota and the entire Great Lakes Region are non-native species, brought over from Europe long ago. They’re beneficial to farmers and gardeners, aerating the soil so water and other organic material can move through, but harmful to woodlands, where they disrupt the “Duff” layer of decomposing material on the forest floor, making it difficult for young plant to take root and grow. The lack of undergrowth affects the animal life as well, as hiding places and nesting grounds disappear.
If you like to fish or do worm composting, you can help! It’s very important never to discard unused worms in forests or even water (worms don’t drown.) Just throw them away in the garbage. Some worm mixes contain Asian earthworms of the genus Amynthas, which have become a threat in Minnesota. These worms are also called Jumping Worms since they are very active and lots of them can live together in one place causing lots of damage to forests.
If you’re interested in studying the worms in your back yard, you can bring them to the surface using ground mustard seed in water. A great science experiment is to measure out a one square foot sample plot (35cmx35cm) with string and stakes, and pour about half of a your mustard mixture (1/3 cup ground mustard dissolved in 4 Liters of water) over the dirt in your grid. Wait for the worms to come up, and when they’ve emerged completely, grab them and put them in a container. When they stop popping up, add the rest of the mustard mixture to the plot and wait for a second batch of worms to appear from deeper in the soil.
How many worms did you find? The Great Lakes Worm Watch is doing a study of worms, so you can preserve the worms and send them to their labs for identification, or you can try to identify them yourself. Great Lakes Worm Watch has other resources if you’re interested in learning more about Earthworms!
I spent an hour yesterday doing science with the girls at TXT2012 camp at Dakota County Technical College yesterday, where kids get to explore Technology, Science, Transportation, Health, Design, Technical/Industrial, and Business fields with hands-on projects. I showed them how to make a marshmallow slingshots (and talked about conservation of energy,) we talked about the fact that there are fun, safe experiments to do with kids you might be babysitting (with mom and dad’s permission, of course,) and then we played with red cabbage juice, and talked a little about pigments, flavenoids and anthocyanins. Finally, we did a hands-on chemical reaction using the cabbage juice, vinegar and baking soda.
Here are the experiments I demonstrated and mentioned: Marshmallow Slingshots, “Magic Potion” (Red Cabbage Juice chemical reaction,) Homemade Litumus Paper, CO2 breath test with red cabbage juice
and here are some fun, safe experiments for babysitters that can be done (under supervision) with young children: Tie-Dye Milk, Cornstarch Goo. If you have an iPhone or iPod Touch, these experiments are on the free (and Premium) version of KidScience app, so you can have them with you all the time.
Our Katniss Camp was sidelined by pneumonia and a birthday, but over the next week, we’ll be exploring the how-to and science of fire, shelters and compasses, so check in to see what we’re up to!
This morning, I went on Kare11 Sunrise News to demonstrate some of the survival science we’ve been exploring. Click here to watch!
This week, the kids and I are embarking on a survival science camp. We won’t face starvation or dehydration, but we’ll learn some wilderness survival skills and the scientific concepts behind them. You could put some of these ideas together and take a group of kids to a local park or nature center for a fun, educational field trip or birthday party!
We’re planning to learn about the best way to collect and purify water, how to figure out which way is North, how to build a shelter and stay warm, the art of making a whistle from an acorn and what really works for building a fire (with adult supervision, of course.) Along the way, we can talk about practical things- like what to do if you get lost.
We visited our library and checked out “STAY ALIVE- Survival Skills You Need” by John D. McCann for inspiration and information.
Today, we kicked things off by making a TRANSPIRATION bag, which is a solar still assembled using a clear oven bag, a twisty-tie, and a non-poisonous tree (like a maple.) I’ll write more about transpiration tomorrow, when we measure how much water we’ve collected! We read that in a sunny spot, you can collect between 1 and 2 cups a day.
If you’re interested in watching the Transit of Venus, you may be able to see it better using binoculars, a tripod and a white piece of paper.
NEVER look directly at the sun, since you can permanently damage your retinas (the light sensors on the back of your eyeballs.)
That being said, you can safety view the sun with a shoebox by standing with the sun BEHIND you. All you need is a shoe box without a lid, a piece of white paper, aluminum foil, a pin and tape. It’s perfect for viewing a solar eclipse, like the one coming up this Sunday.
A solar eclipse happens when the moon passes between the sun and the earth, blocking the sun from view. Go to this eclipse calculator to see when and where you can best view the eclipse with your viewer! Here in Minnesota, we’ll see a partial eclipse on Sunday evening.
First, tape white paper over one end of the shoe box (on the inside.) This is your viewing screen.
Then, cut a big notch out of the other end of the shoe box and tape aluminum foil over it.
Use a pin to poke a hole in the center of the foil. If you mess up, you can always put new foil on and try again. The smaller the hole, the better the focus, but we made ours a little bigger than the actual size of the pin.
Now, stand with the sun BEHIND you. (See photo at top of post. The sun is behind her, high in the sky.) NEVER LOOK AT THE SUN THROUGH THE PINHOLE ITSELF.
Hold the box upside down so the pinhole is pointed at the sun behind you. The foil should be behind your line of sight so it’s not reflecting the sun in your eyes. The idea is that the sun will shine through the pinhole and its image will be projected on the white paper as a tiny circle.
Practice on a sunny day (or when the sun peeks out between the clouds) so that you know what to do when it’s time for the eclipse. Small children should be supervised so they don’t try to look directly at the sun.
You can do the same thing using two white index card, poking a hole in one you hold nearest to you and projecting the image on the one you hold away from you (with the sun behind you.)
Enjoy! Watching an eclipse in the 70s after my dad came to school and helped us all make these boxes is one of my earliest “science” memories!
Last week at the Real Pirates exhibit at the Science Museum of Minnesota, I walked below deck on a mock pirate ship, hoisted a pirate flag (Jolly Roger), touched real pirate treasure and played dice with pirates. The bell of the Whydah, a 300-ton pirate ship greeted us, illuminated by lighting and suspended in a huge tank of water. I could almost imagine it spinning and tumbling to the bottom of the sea off the Massachusetts coast. 146 people aboard the ship drowned when The Wyhdah went down.
I was lucky enought to meet the treasure hunter-turned-historian Barry Cifford who discovered the wreck of the Whydah. He explained to us that pirate ships were true democracies, where crew mates were equal, no matter their background, age, race or religion. As a result ,many rushed to be pirates- whether they had escaped slavery, unjust society, or were just trying to make their fortune. The captain of the Whydah, Sam Bellamy, needed money to marry the woman he loved. There was even a 10-year old boy named John King aboard the Whydah when she went down…he left his mother to join the pirates. (My 11-year old claims he’d never do that.)
How did pirates navigate their way around the deep blue ocean well enough to ever utter the words “Land Ahoy?” In addition to maps and the stars, they used tools like the ones I saw from the Whydah: sounding weights to determine sea depth and ring dials to tell time. They also used compasses, simple tools for determining which direction North was, even in thick fog. A compass is an instrument containing a magnetized pointer that shows the direction of magnetic north, and you can easily make one with a needle, a magnet and a piece of cork or Styrofoam and a glass bowl (or pie plate) containing a few inches of water.Cut a slice of cork, maybe 1/2 inch thick) with a bread knife (see photo.) Then, magnify the metal in your needle by stroking it from one end to another with a magnet about ten times. (Go the same direction each time.) Push your needle through the cork or Styrofoam and gently set it in the bowl of water. The needle, which you have turned into a magnet, will line up with Earth’s magnetic field, which runs from the South Pole to the North Pole. It should point North and South if you magnetized it correctly!
Since my goal is to get kids doing science, I was thrilled when Target asked me to do a guest post for abullseyeview.com about three easy experiments you can do with a homemade science kit!
Check it out here.