Kepler's 1st Law
Students will be able to:
Apply the terms eccentricity and elliptical to the shape of planetary orbits
Calculate the eccentricity of an ellipse
What is the shape of the planets' orbits around the sun?
It would seem "natural" for planets to orbit the sun in
circular paths. This was believed to be true until around 1600
when Johann Kepler challenged this idea.
Kepler realized that the planets orbit the sun in an
ellipse with the sun at one of the foci of this ellipse. See what
this means at
http://www.hcc.hawaii.edu/hccinfo/instruct/div5/sci/sci122/BraheKep/keplawone.gif
Eccentricity measures how extreme this ellipse is.
Earth's eccentricity =.017. A perfect circle is an ellipse with an
eccentricity = 0. a straight line has an eccentricity = 1.
Both foci in a circle are together in the center and as we move them
farther apart from each other the ellipse gets longer and approaches
1. To find eccentricity or "e" divide the distance
between the foci by the length of the major axis (the longest side of
the ellipse) or e=d/L. Always express the answer in a decimal
never a fraction.
Visit http://csep10.phys.utk.edu/guidry/java/kepler/kepler.html
Play with e and notice that as e approaches 1 the ellipse gets stretched
out.
How would this law affect an orbiting satellite around
Earth? Read the instructions below the diagram and then change e
at http://observe.ivv.nasa.gov/nasa/education/reference/orbits/orbit1.html
What happens to the satellite if e is too large?
1) Find the eccentricities of the following ellipses:
-
d=2, L=4
-
d=20, L=100
-
d=2, L=100
-
d=9, L=36
2) Based on the list of e values for the ellipses
above, which orbit is the most eccentric? The least?
3) How would you describe the Earth's orbit as
compared to a perfect circle?
Unit: ASTRONOMY
Lesson: The Planets
Students will be able to:
Compare and contrast the general physical characteristics of the nine planets in our solar system.
What are the other planets in our solar system like?
Would it be possible to land on some of the other planets and colonize them? Is there life on any of them? Could we survive there?
Now that we have determined that the planets of our solar system orbit our sun (in slightly elliptical orbits), let’s explore some of the differences and similarities between these planets. Could we land on one of these planets and just build a house and live there? How alien are these places? What conditions would we find there?
As you visit the following planets keep a list of the general physical characteristics of each one. Concentrate on the images. Click on the thumbnail images (the small ones) to see an enlarged version. Try to see as much detail as possible.
The first four planets are called the inner planets. Start out with Mercury.
Here are more images to see. What is the most striking feature of its surface?
Now travel to Venus.
Here are more images to see. What feature of the atmosphere makes it inhospitable? Now back to
Earth for a quick breather. It may be your only one without a helmet for a while!
Here are more images to see.
Now on to Mars. Notice all the channels on the surface. What caused those? Any evidence of
volcanoes? Here are more images to see.
At his point we must cross the asteroid belt to visit the outer planets -
Jupiter (can you see the great Red
Spot?) Here are more images to see.
Saturn
(notice the rings!) Here are more images to see.
Uranus Here are more images to see.
Neptune
Here are more images to see.
Pluto
Here are more images to see.
What problem would a spacecraft have landing on most of these outer
planets?
Answer the following questions in full sentences.
1)What is the main physical difference between the inner and the outer
planets?
2)Which planet does our moon’s surface look the most like? What do you
think was the process that caused these features?
3)Do all the planets have moons?
4)Compared to the other outer planets, what is unusual about Pluto?
5)Do any of the other eight planets appear to be habitable for humans?
Explain why or why not.
6) Why do we need to take such special care of the Earth?
Unit: ASTRONOMY
Lesson: Heliocentric vs.
Geocentric Models
Students will be able to:
-distinguish between the heliocentric and geocentric models of the solar
system.
-discuss the retrograde motion of planets to support the heliocentric
model.
What is the spatial arrangement of the sun, planets, and stars in our
universe?
Picture yourself as an
ancient Shepard. Most of your life is lived outdoors and you are
familiar with the sky both during the day and at night. As you watch the
sun travel across the sky during the day and the stars across the sky at
night, it would seem that the Earth was the center of creation. You
would be taught that humanity is so important that we are the center of
the universe. Imagine how you would feel if someone told you it was not
true - that we are only one planet among nine that orbit an ordinary
star among billions of other stars. Could you accept this? Would you
want to accept this?
As you observe the sun’s apparent motion across the sky during the
day, it would seem as though the sun could be moving around the Earth.
Is the Earth the center of the solar system? Which is actually moving
the Earth or the Sun? How could we prove it? The geocentric model of the
solar system was developed by Ptolemy and was the accepted model for
about two thousand years until it was challenged by Copernicus in the
1500s.
http://windows.ivv.nasa.gov/cgi-bin/tour_def/people/ancient_epoch/ptolemy.html
Read this page to learn about Ptolemy.
http://www.intelligentchild.com/astronomy/copernicus.html
Now read about Copernicus.
In what way is the heliocentric
model different from the geocentric
model? Compare both models side
by side.
How
can we prove that the heliocentric model is correct? This is difficult
without space flight. However, the retrograde motion of some of the
planets in our night sky is awkward and complicated to explain using the
geocentric model. The heliocentric model offers a simpler explanation.
http://alpha.lasalle.edu/~smithsc/Astronomy/retrograde.html
Visit this site to learn about the retrograde motion of the planets and
its impact on how people might decide between the two models.
Conclusion:
Using the information from this lesson, pick a position in support of
either the geocentric or the heliocentric model. Write an essay in which
you try to convince someone of the opposite opinion that your model is
the correct one.
Unit: ASTRONOMY
Lesson:
Visitors From Outer Space
Students will be able to:
Describe the effects of bombardments on a planet’s surface.
Explain the threat that meteorites pose to life on Earth.
We know from our observations of the moon that objects have fallen
from space and created craters on the moon’s surface. What are these
objects and do they also fall to Earth? If they do, what effect would
these impacts have on our planet?
Did you know that we are invaded from outer space every day?
Particles left over from the formation of the solar system continuously
rain down on Earth. Most of these objects are too small to be noticed.
But some make a "Deep Impact"! What are these objects? How big
can they be? Are they really all that dangerous?
There are several different types of visitors from outer space. They
originate as asteroids, comets, and the dust left over from a passing
comet’s tail. Most of the debris that falls to Earth is so small that
it burns up in the atmosphere. These are called meteors. You have
probably seen such a "shooting star". If the particle is too
large, it doesn’t disintegrate from the heat of the air friction. It lands
on the ground and is then called a meteorite.
Comets are believed to be "dirty snowballs" consisting of
the primordial material that formed the solar system 4.5 billion years
ago. By analyzing and studying them, we learn about our origins. In
1997, we were visited by comet Hale Bopp. Although this comet didn’t
hit the Earth, it was an important comet because scientists had the
technology to make some interesting discoveries about its
composition. http://www.halebopp.com
Visit this site to view some interesting images of this comet.
Click on the titles to see larger images. Notice that there are two
tails. The yellowish white tail is composed of dust and the blue is made
of gases ionized by the solar wind.
Another comet Schumacher-Levy 9 made history in 1994 because it broke
into more than 20 pieces and then collided with the planet
Jupiter. http://seds.lpl.arizona.edu/ftp/astro/SL9/images/recent/ALL/KECK_H.gif
Look at some of the images of these impact sites.</a> Each impact
site was estimated to be about the size of the Earth. What do you think
would have happened if this comet had hit Earth instead of
Jupiter? http://sherpa.sandia.gov/planet-impact/comet/
To see what might happen if a comet fell into the Atlantic ocean off the
coast of New York City visit this site.
Has a comet or asteroid ever hit the Earth? A giant comet is thought
to have caused the extinction of the dinosaurs. Earlier in this century,
a comet or asteroid might have exploded above Russia. http://www.galisteo.com/scripts/tngscript/default.prl
Read about Tunguska http://www.jpl.nasa.gov/sl9/back2.html
Visit this site to learn more about the probability of Earth being hit
by an asteroid or comet.
Conclusion:
1) Does Earth ever get hit by asteroids or comets?
2) How large does the meteorite have to be in order to be dangerous?
3) How accurate are movies like Deep Impact and Armageddon?
4) It has been estimated that the number of government people who are
searching the sky for near-Earth objects (that could become a doomsday
comet or asteroid) is less than the number of people who work at a
McDonald’s. What do you think of this policy? Why?
5) What effect might meteorites have on the process of evolution?
6) It may be too late for the dinosaurs...but is it too late for us?
Unit: ASTRONOMY
Lesson: The Moon’s Shadow
Dance
Students will be able
to:
Describe the mechanism of how solar eclipses occur.
Compare and contrast the three types of solar eclipses.
What is a solar eclipse?
On August 11, 1999, an estimated 2 billion people viewed the last
solar eclipse of the millennium. Some of them were lucky enough to be in
the path of totality in Europe and part of Asia. Many people outside the
eclipse path watched the eclipse live on the Internet or on CNN. What is
so special about a total solar eclipse? Why is it so rare? How do you
get to see one?
Although our moon is so much smaller than the sun, it is also much
closer to us. By an amazing coincidence, these two factors even out so
that the apparent sizes of the moon and the sun appear equal in the sky!
Our Earth is the only planet in the solar system where this precise
matching of size occurs. Due to this matching of apparent sizes, the
moon can occasionally cover the bright disk of the sun’s photosphere
and reveal a part of the sun we normally can not see: the corona.
If you are ever lucky enough to witness such an awe-inspiring event,
you will never be the same. Let’s take a look at an animation that
shows us the August 11, 1999 eclipse from the perspective of outer
space. http://members.aol.com/tfroberg/eclipse/animate.htm
Notice how the moon’s shadow travels across the Atlantic Ocean,
Europe, and then part of Asia.
This next section shows the difference between the three types of
eclipses - partial, annular, and total.http://members.aol.com/tfroberg/eclipse/types.htm
Read about the types of eclipses and study the animation carefully.
A total eclipse of the sun goes through a partial phase, peaks at
totality, and then goes into another partial phase until the entire sun
is visible again. http://www.eclipsechaser.com/eclink/image/total79.htm#seq
View this composite image to see the different phases of a total
eclipse.http://iseeyou.com/eclipse/photos-03.html
Here are some more images of an eclipse. Click on the smaller images for
an enlarged view. You should know that due to the limitations of film,
no photograph could truly capture the amazing beauty of totality. Also,
the partial phases are photographed through a special filter, which is
why the sky looks black.
http://www.eclipse99.nasa.gov/pages/amazing.html
Click here for some interesting facts about solar eclipses.
The next total solar eclipse will be in southern Africa in June 2001.
However, the next total solar eclipse in the U.S. won’t be until 2017.
If you don’t want to wait that long, you might want to become an
eclipse chaser.http://www.eclipsechaser.com/
Here’s how.
1) Draw a diagram that illustrates the relative positions of the
Earth, Sun, and Moon during a total solar eclipse.
2) List the three types of solar eclipses. What are some of the
differences between the three types of solar eclipses?
3) Draw a diagram of how the sun appears during each type of solar
eclipse.
4) What happens during totality?
5) Why doesn’t the moon completely cover the sun during an annular
eclipse?
This page created by Elizabeth Ackermann,
Miller Place School District
