Changing Shadows

The Earth is both rotating and revolving.

It revolves one time every 23.9344 hours.

Avery is getting into her
"The Night Max Wore his Wolf Suit" mode.  This shot is
from about 9:00 am, at pre-zenith.

It revolves around the Sun once every 365.25636 days (this is why we need an extra day every four years, a "leap year.")

From Maurice Sendak's classic book,
"Where the Wild Things Are."

Avery's one-footed, wolf pose.

It takes 8.319 minutes for light to arrive from the sun each day.  (Said another way, we are 8.3 light minutes from the sun.  We are "One Astronomical Unit" from the Sun or 92.99 million miles.)

The Earth revolves at 27.906 km/minute (that's 1674.4 km/hour or 1040 miles/hour).

It was "Super Hero" day as part of Spirit Week.  Mia, Sierra, and Claire strike an appropriate pose.

The Sun "rises" in the East.  It "sets" in the West.  The sun isn't moving though!  It is the Earth's rotation that makes the Sun appear that it is moving through our sky.

Part of the investigation involved playing games with the
shadow.  Here Mr. R. and Chase make our shadow hand
hold onto the shadow post.  (This is a telling picture of my
bald spot.  I didn't know it got that bad. Why hasn't
anyone told me?)

We did our most recent investigation near the first day of Fall (Autumnal Equinox is always on Sept 21/22 (depending if it's a Leap Year).  For us in the northern hemisphere, and because of the Earth's 23.5 degree tilt, the Sun's zenith (highest point in the sky each day) changes as we pass through the seasons of the year.  (More precisely, it is our relation to the Sun in regard to our tilt that causes the seasons.)

Again, because of this tilt, the first day of summer (June 21/22) finds the sun having the highest zenith of the year.  Conversely, on the first day of winter (December 21/22) it is at its lowest zenith.  This also accounts for the first day of summer having the longest amount of sunlight.  In winter, we have the shortest.

We were all amazed at how quickly the
shadows shift.  Here you can see the 'blue' shadow at 9:00,
then the 'purple' shadow just 15 minutes later!!  And, see
the shadow to the left at 11:30. During the assessment
students will need to be able to explain where the Sun is
shining from and what direction the people in the picture
are standing.

Our investigation on this Fall day gives us good scientific information on how the Sun's position changes over the course of the day.

We learned this by making observations of these changing shadows.

Here are the students tracing their first shadows just after 9:00 am.  This was pre-zenith.  Notice how much
the stop sign's shadow has moved in just a few short minutes.

The students observed that when the Sun rises in the East
and is still low in the sky, that the shadows are much longer.

As the Sun approaches its zenith, like the yellow chalk
here at 11:30, we notice the shadow lines getting much shorter.
We also notice a change in the direction of the shadow.

Later in the day, at 2:00, the Sun is now past its zenith
for the day, the shadow is beginning to get longer again.
It is also pointing in the opposite direction as compared to
the morning/pre-zenith.

Jenna gets her shadow traced while the shadow of her
teacher takes her picture.