SMMARTideas

SMMART SCIENCE: Solar Still

Sun Power...amazing!  An hour and a half at the pool yesterday and not getting enough sunscreen on my own back...a beautiful, (slightly painful) pink burn.  It's  amazing how strong the sun's rays are and the magnitude of power from so far away in the solar system. 

"The sun is the closest star to Earth, at a mean distance from our planet of 149.60 million km (92.96 million miles). About one million Earths could fit inside the sun. It is held together by gravitational attraction, producing immense pressure and temperature at its core. The sun has six regions -- the core, the radiative zone, and the convective zone in the interior; the visible surface (the photosphere); the chromosphere; and the outermost region -- the corona.

At the core, the temperature is about 27 million degrees Fahrenheit (15 million degrees Celsius). The sun's surface -- the photosphere -- is a 500-km thick (300-mile-thick) region, from which most of the sun's radiation escapes outward and is detected as the sunlight we observe here on Earth about eight minutes after it leaves the sun." (http://solarsystem.nasa.gov/planets/profile.cfm?Object=Sun&Display=OverviewLong)

The heat of the sun evaporates water, which changes water from it's liquid state to a gaseous state.  Help your child see the power of the sun by making a simple Solar Still. (www.pbskids.org/zoom)

You will need to fill a large bowl with a few cups of water.  You can get creative with the water...put some food coloring in the water for a visually effective lesson, or mix in salt to represent ocean water.  You can even try this activity with orange juice or cola.  The evaporated water will be purified by the sun's evaporation/condensation process, so you should have a clearer, and less-salty version than you started with.

Place a glass or bowl inside the pool of water, with the glass being just above the water level and lower than the rim of the large bowl.  (You may wish to see if a metal bowl works better at recovering purified water than a glass bowl).  Cover the bowl with plastic wrap and place a stone in the center of the plastic wrap, just over the glass.  When the water evaporates and condenses onto the plastic wrap, the weight of the stone will lead the purified water droplets to drop into your glass.

Set your Solar Still out in the sun.  When you have collected your purified water, have your child observe and taste the differences between your original liquid and the purified water.