Think About It Thursday….


   Why Do Leaves Fall Off Trees?

During that process, the trees lose a lot of water – so much water that when winter arrives, the trees are no longer able to get enough water to replace it.

And so now we know. Leaves fall—or are pushed—off trees so that the tree can survive the winter and grow new leaves in the spring

Make sure you check out HTHT’s Experiment page, but especially check out the science experiment, Binocular Build & Scavenger Hunt!

You could build a binocular, then go on a scavenger hunt to find all the different color leaves!

Happy Hunting!


Source: Pixabay Images

Fall into Hibernation With Fun Science!

Beautiful leaves, fruitful harvests, and cooler weather are all things we think of when we picture fall.  It is a transitional time from the sweltering summer months to the frigid winter months.  For many creatures, fall is also a transitional time when they prep for hibernation.

What exactly is hibernation?

Bears snoozing in a den is what many of us probably imagine when we think hibernation, but a lot of different types of animals hibernate and experience similar processes.  Hibernation is a state of inactivity and metabolic slowdown in endotherms i.e. warm-blooded organisms. It is characterized by low body temperature, slow breathing and heart rate, and low metabolic rate.

Many ectotherms (i.e. cold-blooded organisms) seem to hibernate via a similar process called brumation.  Remember that the main thing that differentiates warm-blooded and cold-blooded creatures is that warm-blooded organisms can self-regulate their temperature and metabolic responses.  Whereas cold-blooded organisms’ metabolism reacts in response to their environment.  So cold environment = slower metabolisms for all ectotherms versus cold-environment = hibernation for some endotherms but not all.  Fish seem to hibernate but are an example of an ectotherm slowing down in response to the cold.

Hibernation is a considered a period of energy-saving torpor.  Torpor is a state of decreased physiological activity in an animal and includes a lower body temperature and metabolic rate.  Some animals experience what is called daily torpor, which refers to a period of low body temperature and metabolism lasting less than 24 hours.  For instance, hummingbirds experience a state of torpor just at night and have been known to hang upside down from their perch while in this state.

Hibernation in general occurs in winter and the opposite of hibernation is called aestivation, which occurs in the summer months.  Many invertebrates and amphibians have an aestivation cycle that helps them survive hot, arid seasons.

Why hibernate?

Whether it is hibernation or aestivation it is all about surviving extremes.  It is a way for animals to survive difficult conditions.  For instance, winter for a bear or squirrel means cold temperatures, not a lot of food, very little camouflage cover.  Despite being in a vulnerable torpor state, being out in those conditions seem way riskier. The risk of vulnerability must have been outweighed by the benefits of hibernation for bears and other creatures to evolve this unique mechanism.

Prep for hibernation

Bears, for instance, have a period prior to hibernation where they eat and drink in excess to build up their fat stores for hibernation.  Gorging themselves on nuts, berries and other food sources while they are around help them survive once they go into torpor and hibernate for several months.  They also have a transition period where they aren’t hibernating but their metabolism is beginning to slow so they start to eat less and sleep more.   The creation of a cozy den or nest is also essential for hibernation. This keeps body heat contained, protects from the elements, and conceals the hibernating animals.

Can humans hibernate?

You might feel sleepier in the winter months, but humans never evolved to hibernate.  Part of that reasoning is that since we evolved in equatorial, tropical Africa where there is a consistent food supply we would not have needed to hibernate to escape harsh conditions.  We also would have been a top predator, so less likely to need hibernation to avoid predators.  We are also bigger and most hibernators are small with the obvious exceptions here and there (bears).

Our hearts are also different from other mammals that hibernate.  Our hearts contract in response to calcium. So, if our heart gets too cold, there is a buildup of calcium and we go into cardiac arrest.  Mammals that hibernate have a special pump that gets rid of excess calcium, which means their hearts continue to beat at much lower temperatures.

Scientists are interested in engineering ways for humans to hibernate because it would aid in long-term space travel.  Astronauts must exercise 6 hours a day in space to prevent muscle and bone atrophy, which might be avoided if they could hibernate.  Hibernation obviously would reduce the amount of supplies they would need, and could protect from radiation.  A year in space right now is the max an astronaut can do without significantly increasing the odds that they’ll get cancer and other side effects due to radiation.

Think About It Thursday: Why Do Leaves Fall Off Trees?

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When winter approaches, our part of Earth receives less sunlight, and the air grows colder, this season is commonly known as “Fall”.   When these changes happen, trees prepare for winter. People believe that leaves die on the tree and the wind blows them off the tree. According to Peter Raven, president of the Missouri Botanical Garden and a renowned botanist, “the wind doesn’t simply pull leaves off trees. Trees are more proactive than that. They throw their leaves off.” Deciduous trees have cells in them that act like scissors. These cells build up a thin bumpy line that push the leaf, bit by bit, away from the stem. You can’t see this without a microscope, says Peter Raven. The tree will then seal the spots where the leaves were attached and bunker down for the winter months.

The falling of these leaves on a tree actually helps the tree to survive the cold, dry air of winter. In the warm seasons, leaves use sunlight, water, and air to make the tree’s food, in a process called photosynthesis. In that process, the tree loses a lot of water through tiny holes in the leaves. In winter, the tree does not get enough water to replace what it would lose through the leaves. If the tree did not seal the spots where the leaves grow, it would die. When spring brings warm air and fresh water, the tree will sprout new leaves and start growing again.


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September 23, 2015 marks the first day of Autumn for this year! What is Autumn exactly? Yes, it’s the season that falls between Summer and Winter but there is more science involved than that. Autumn or Fall is brought by the September Equinox. 

Because Earth doesn’t orbit upright, but is instead tilted on its axis by 23-and-a-half degrees, Earth’s Northern and Southern Hemispheres trade places throughout the year in receiving the sun’s light and warmth most directly. We have an equinox twice a year – spring and fall – when the tilt of the Earth’s axis and Earth’s orbit around the sun combine in such a way that the axis is inclined neither away from nor toward the sun. Earth’s two hemispheres are receiving the sun’s rays about equally around equinox-time.

What are some of your favorite Fall activities? Perhaps jumping into freshly raked leaf piles? Wandering through a windy maze made from corn husks? Maybe sipping on some hot apple cider or something pumpkin spice flavored? Whatever your favorite Fall activity, this season is sure to bring beautiful colors and lots of fun!

Think About It Thursday: Why Do We “Spring Ahead” and “Fall Back”?


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As you may already know the end of Daylight Savings Time is up-coming this Sunday, November 1 2014. But what does the ending of DST really mean? Well you may have heard the expression “Spring ahead — Fall back” over the course of your lifetime.

In the Spring, Daylight Savings Time starts, when we set our clocks AHEAD 1 hour. This allows us to get up earlier so that we may enjoy longer amounts of daylight at the end of the day! There are a ton of added benefits to having more daylight in one day including retail stores staying open later, time for sporting events after school, and more time for activities when getting out of work at 5pm.

In Autumn, we “Fall back”. This “Standard Time” is when we set our clocks back 1 hour. It is said that inventor, Benjamin Franklin, is often credited for being the one to first come up with Daylight Savings Time. “He had proposed to economize the use of candles by getting people out of bed earlier in the morning, making use of the natural morning light instead.” (1)

In the U.S., clocks change at 2:00 a.m. local time. In spring, clocks spring forward from 1:59 a.m. to 3:00 a.m.; in fall, clocks fall back from 1:59 a.m. to 1:00 a.m.

“2:00 a.m. was originally chosen as the changeover time because it was practical and minimized disruption. Most people were at home and this was the time when the fewest trains were running. It is late enough to minimally affect bars and restaurants, and it prevents the day from switching to yesterday, which would be confusing. It is early enough that the entire continental U.S. switches by daybreak, and the changeover occurs before most early shift workers and early churchgoers are affected.” (3)

Daylight Savings Time Changes 2010-2017

For more information about Daylight Savings Time please visit these resources below.

Resources: (1)



Happy Autumnal Equinox!

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Wishing everyone a happy Autumnal Equinox or first official day of Fall today! In celebration today’s post will be about the science behind building one of our favorite Fall pastimes, the corn maze.

There is way more than you can imagine that goes into creating a corn maze. First, the farmer needs to decide on which hybrid of corn he needs to plant in order for it to be the right height and stalk strength. Secondly, he must keep a close eye on the corn crop during the growing process for a disease called “stalk rot”. Stalk rot is a key factor when there is improper fertilization and moisture stress on the plant. Then the farmer needs to think about having an area large enough to plant his corn and produce his maze. Another note to keep in mind is that he should not overcrowd the corn plants either. 

Once the corn is fully mature and tall enough, the farmer will start to cut pathways. Cutting the pathways isn’t just as simple as cutting out rows into the corn. Most corn mazes these days follow a specific theme or classic movie. So the farmers will use a GPS navigation device in order to plan and execute precise pathways into their corn maze! Some of the best corn mazes have “bridges” built into the middle of the maze, where tourists can climb up the stairs and look out over the corn that they are lost in!

If you have never experienced a corn maze for yourself, I encourage you to try out this extremely fun Autumn pastime! Here is a list of all the corn mazes in the United States!

Stop by one and get lost in the corn today!

Think About It Thursday: Why Do Leaves Change Colors?

Leaf color comes from pigments. Pigments are natural substances produced by leaf cells. The three pigments that color leaves are:

  • chlorophyll (which produces the green color)
  • carotenoid(produces yellow, orange, and brown colors)
  • anthocyanin (produces a red color)

Chlorophyll is the most important of the three. Leaves contain chlorophyll in order to use the sunlight to produce its own food through the process of photosynthesis.

Carotenoids are organic pigments that are found in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms.  Carotenoids create bright yellows and oranges in familiar fruits and vegetables. For example, corn, carrots, and bananas to name a few.

Anthocyanins are pigments that may appear red, purple, or blue depending on the pH, they add the color red to plants, including cranberries, red apples, cherries, strawberries and others.

In the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible. Most anthocyanins are produced only in autumn, and only under certain conditions. Not all trees can make anthocyanin, but sugar maples seem to have the easiest time in doing so.


Resources: State of New York: College of Environmental Science and Forestry: Environmental Education for Kids:

The September Equinox of the Northern Hemisphere Approches


As the September Equinox approaches it is important to understand how the equinoxes were discovered and how to prepare for the astronomical event.

Our human ancestors spent much more time outdoors than humans now a days. They learned to track the patterns of the sun and eventually used it to tell time and the seasons. They built elaborate observatories in order to track the sun’s progress throughout the year.

Because Earth doesn’t orbit upright, but instead is tilted on its axis by 23 1/2 degrees, Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly. We have an equinox in the spring and fall, when the tilt of the Earth’s axis and Earth’s orbit around the sun combine in such a way that the axis is inclined neither away from nor toward the sun. Earth’s two hemispheres are receiving the sun’s rays equally now. Night and day are approximately equal in length.


So how do we prepare for this astronomical event, on the day of the autumnal equinox, at sunrise/sunset, go outside to your yard or other favorite site for watching the sky and you will be able to decipher the cardinal directions. The sun will rise at due East and set at due West! If it is a clear morning/evening, be prepared for some amazing views as well!

The 2014 September equinox occurs on September 22, at 9:29 p.m. in the central United States.