By Nicole Rhodes, Lead STEM Tutor

The Winter Solstice is the shortest day of the entire year–meaning there is more dark than light in a 24-hour period. It is when the earth is tilted the furthest away from the sun. For us in the Northern Hemisphere, this happens on December 21st (or sometimes actually on the 22nd), but in Australia, the Winter Solstice happens in July! 

In Massachusetts, Winter Solstice usually marks the onset of colder weather, frequently accompanied by snow and ice. Kids might observe water droplets condensing on windows, as there is a bigger difference between indoor and outdoor temperatures. They may also be fascinated with frost and snowflakes. We also need to wear warmer clothing, while wild animals keep warm on their own. How does this all happen? Here are four different investigations to help understand why it is colder and darker this time of year, make your own crystals to learn about snowflakes, and figure out how other animals stay warm in the severe winter temperatures of the Arctic! 

Winter Solstice Science Activity 1: How many hours/minutes/seconds of daylight are in each day? Why does it change? How does this make seasons in the Northern and Southern Hemispheres? 

Depending on where you are in the world, the sun rises and sets at different times each day. If you were at the north or south pole, it would actually be completely dark for 24 hours one full day a year! If you were at the equator, the sunrise and sunset times stay close to the same year-round. It all has to do with how the tilt of the earth changes throughout the year in relation to the sun. 

SEASONS and SUNLIGHT EXPLORATION

Materials

–Globe, or styrofoam ball painted to look like Earth

–Chopstick or skewer (optional, but helpful to keep track of Earth’s axis)

–Lamp (lampshade removed)

–Dark room

One way to visualize this is to use a globe (or any sphere) and a lamp in a dark room. Each kid can make their own planet Earth by painting polystyrene balls and (with an adult’s help), skewering them at the north and south poles and hold the skewer at 25 degree angle (the Earth’s axis is 23.5 degrees). Hold the Earth(s) at the same angle by using a target in the room

 (e.g. a ceiling corner). Move the Earth around the lamp “sun” and observe where the light shines on the planet. 

12 MONTHS of SUNSET PHOTOS

Materials

–Camera

–Set location

–Watch

You can also witness the changing angle of the Earth in relation to the Sun if you step outside at the same time for an extended period of time–try once a week for a month. Notice where the sun is (without looking directly at the sun–it can damage your eyes!). Wear sunglasses and take a photo from the same exact location. After a month, compare your photos–where is the sun? How did it change? Do you notice any patterns? How does this relate to the rotation and tilt of the Earth in relation to the Sun? How do you think it relates to seasons? You can go even further and do this once a month for a year! This has become a viral trend on the internet, like this set of 12 photos taken at the same time of day once a month from Italy.

Winter Solstice Science Activity 2:  How do animals stay warm outside in winter?

Have you ever wondered how a polar bear can dive into freezing cold water covered in ice chunks? Animals like polar bears, seals, and walruses in the Arctic and Antarctica all have a thick layer of fat, called blubber, that insulates their bodies from freezing temperatures. You can experience how it feels to have (part of) your body covered in “blubber” with this experiment. 

Materials

–Vegetable shortening (beware–a whole container might be used!)

–Different types of gloves (ie. wool, fleece, or cotton)

–Non-latex glove (can be found at a pharmacy)

–Plastic wrap

–”Arctic” Ice bath (bowl filled with water and ice cubes)

Directions

1. Define the Problem: You are an animal who lives in the Arctic or Antarctica, and you must dive into freezing cold ocean water to catch your food. How will you not freeze to death? What type of material will insulate your hand the best from freezing cold water (a bowl of ice water)? Try out the ice bath with a bare hand. How long can you hold it there without feeling cold? 
2. Develop a Solution: Decide on different insulating materials to test, such as a wool glove, cotton glove, or vegetable shortening.
3. Create a Prototype:  Test out different materials layered between two plastic gloves (we are testing insulation, not waterproofing, though that could be a different experiment). First, put on a non-latex glove, then test different types of insulation. Layer the insulation over the first glove; put your hand in a fist and cover with a third layer of plastic wrap. 
4. Test out your Prototype: Dunk your insulated hand in the ice bath, and try to hold it there for at least 30 seconds. How does it feel? You could even put a thermometer in your hand to see the temperature after 30 seconds. 
5. Reflect and Retry: Try other insulating materials.

Winter Solstice Activity 3: How do crystals form?

Explore the process of recrystallization with the fun hands-on experiment. There are multiple open-ended questions that you can test, like how water temperature, solution saturation, and pipe cleaner shape change how the crystals form. Chemists frequently use recrystallization to separate products of a reaction, since it is much easier to separate a solid from a liquid. Solubility is the largest amount of something that can be dissolved in something else, like how much Borax can dissolve in water. The amount changes with temperature (the hotter the water, the more Borax it can dissolve). If you make a hot, saturated solution of Borax and water and then cool it down, the solubility decreases and Borax crystals will fall out of the water. The purer the solution, the larger the crystals that will form. If there are a lot of extra particles, say dust, the crystals that form will be smaller. Kids will marvel at how matter changes right in front of their eyes!  Extend your exploration with the links to further reading about how snowflakes form their crystals from water droplets at the right temperature and humidity. 

Materials

–Borax laundry booster (use with caution– Borax is harmful if swallowed, inhaled or contacts eyes)

–Water

–String

–Measuring cup

–Empty container

–Food coloring (optional)

–Popsicle stick 

–Pipe cleaners

–Cookie cutters as a shape mold (optional)

Directions

Define the Problem: How can you make the biggest (or smallest) crystals? 

Develop a Solution: Will crystals form best at room temperature or in an ice bath?

Create a Prototype: Get your environments ready (make an ice bath with a bowl of water filled with ice)

Test out your Prototype:  

1. Bend a pipe cleaner into the shape of a snowflake, icicle, or any shape you want!
2. Tie one end of your pipe cleaner onto a string, then tie the loose end onto a pencil or popsicle stick. 
3. Mix slightly different amounts of Borax with 1 cup of water. Stir until the Borax is fully dissolved (¼ c Borax per 1 c water tends to make the most reliable crystals, but you might want /different types of crystals!). If you want, you can make things colorful by adding 15-20 drops of food coloring. Hint: A fully saturated solution means that there is no more room for the Borax to be in the water solution…it must go somewhere!
4. Use the string to tie your snowflakes and stick/pencil together.  Make the string long enough to fully submerge your snowflake in the Borax.
5. Use level tablespoons to add Borax to 2 cups of recently boiled water (make sure your water is not at an active, rolling boil, to prevent the Borax power from splashing out). Count how many tablespoons you can add until the Borax no longer dissolves when you stir it in. Once it no longer dissolves, you have a “saturated” solution. To add color to the crystals you can add a few drops of food coloring.  
6. Pour equal amounts of the saturated solution into two jars. Submerge your pipe cleaner creation in each jar, resting the stick across the top of the container.  Adjust the string if needed to keep it in the center of the container and not touching any side.
7. Let one jar sit in an ice bath, while the other jar sits at room temperature. Wait for at least 5 hours. With a clear container, you can peek at the crystals as they form, but be careful to not let the solution mix or jiggle at all. 

Reflect and Retry: Observe the crystals that formed in both jars. Do they look different? How? You can do more reading about how impurities can get caught in the crystals when the solution cools more rapidly. How do you think that changes how snowflakes form in nature?

Further Reading:

• How do snowflakes form? Get the science behind snow | National Oceanic and Atmospheric Administration
• Solubility Science: How to Grow the Best Crystals | Scientific American 

Why are snowflakes symmetrical? How can ice crystallizing on one arm ‘know’ the shape of the other arms on the flake? | Scientific American

Watch the segment live on Tuesday, December 12 on WWLP News Channel 22’s Mass Appeal

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