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A WALK THROUGH THE SOLAR SYSTEM
or
SPACE IS FAR OUT
by Mike Roach
This material has been written by Mike Roach with reference to
information from various astronomical sites and Educational material
available from NASA and ESA.
These days we are surrounded by knowledge via the internet. Only a few
years ago students looked at text book versions of the Solar System which
gave a distorted picture of the enormous distances between planets. Lately
they can visit Video Clips from You Tube, watch TV programs and simulations
to take them on a more exciting journey.
Many modern computer simulations and videos allow us to capture a glimpse
of what it would be like to travel in our Solar System, and even further, within
our Galaxy the Milky Way, to other stars, just like our sun, but none have the
capacity to show the gigantic scale of our Universe.
This simple activity will do more to impress on your students the remarkable
engineering and scientific progress that has taken place over recent years
than any other I have seen. Taking these small steps will enable your
students to cope with the flood of information available and lead them on a
path to understanding Our Place in Space.
As you walk your students through the Solar System, many questions will be
forthcoming, but as this should be an introductory activity, you will not need to
answer all of the questions now. They can form the basis of a learning
programme which will generate wonder and amazement within your students
as they try to satisfy their genuine thirst for knowledge in this fascinating topic
area. Even the most knowledgeable of astronomers and astrophysicists do
not have all the answers, so this puts the humble science teacher in very
good company.
LESSON FOCUS
Teachers should pace out distances (only approximately) prior to the lesson
and paste up planets to at least include Saturn although I have provided the
rest.
Although the students will have many questions the teacher should not
attempt to answer all of them, and it is important that the walk is completed
with plenty of time to hand out the Worksheet for students. The table should
be photocopied and handed out to students.
Suggested year levels: 6 - 10
TO THE TEACHER:
PREPARATION:
The lesson is most successful if you prepare your walk in advance by pasting
the planets at the appropriate distances on the insides of windows
somewhere in your building complex. Note that you can stop after Saturn, and
simply double, triple and quadruple the distance you have walked. This is
effective enough, but you may have the time and inclination to take your class
the whole way. If you can leave the planets up for some time, you will observe
many students looking at the information contained and those who are not in
your class puzzling at why the planet is on show at this particular place. You
may also have posters of the various planets, and spacecraft that have visited
them, or flown by, which you could post near each planet station.
INSTRUCTIONS TO SET UP "THE WALK"
1. The cards are in a separate document called Walk the Planets. Display
the SUN at one end of a long corridor or on a window at the start of
your walk.
2. Draw in box provided the diameters of the planets\
3. Pace out the distances (no need for too much accuracy on this scale)
4.
When you look at the distances involved you will probably want to stop
at SATURN. This is fine since (very approximately) you can say that
Uranus is twice as far from this point, Neptune three times and Pluto
four times.
5. There is a complete set of these stations available in the attachments.
A WALK THROUGH THE SOLAR SYSTEM
Compare the size of the planet and it's distance away to our Sun. The
Sun is 109 mm in diameter.
HERE IS THE PLANET
.........................................
DISTANCE from
Sun
OBJECT
DIAMETER (Size)
Sun
109mm
Mercury
0.33 mm
5m
Venus
1 mm
8.5 m
Earth
1 mm
12 m
Mars
0.5 mm
18 m
Jupiter
11 mm
62 m
Saturn
9 mm
114 m
Uranus
4.0 mm
230 m
Neptune
3.9 mm
360 m
Pluto (at maximum
orbit)
0.25 mm
480 m
Proxima Centauri
(pointer)
120 mm
3,200 kilometres
Sirius (the brightest
star)
20 mm
6,500 kilometres
ADDITIONAL NOTES FOR THE TEACHER
Once the students have some idea of the immense scale of our own Solar
System, it seems appropriate to mention the hundreds of billions of stars that
make up our Galaxy, the Milky Way, and then the hundreds of thousands of
Galaxies that exist in our Universe.
After the students have completed the "Walk" (you may be at Saturn or even
Pluto, if you are adventurous) ask them to guess where the closest star (sun)
is to our own Sun on the scale that we have been walking. Guesses come in
thick and fast, but few believe that you would have to walk across Australia to
reach Proxima Centauri, actually a part of a three sun solar system, which
appears conveniently each night as one of the pointers to the Southern Cross.
Now it is time to move to the scale of light years, as the students begin to
appreciate the gigantic scale we will be operating in. I normally start back on
Earth, and tell the students that light travels very fast, in fact nothing travels
faster, at 300,000 km/sec.
If I was to go to the moon and flash a torch back towards Earth it would take
1.3 seconds for the light to reach us. If I was to go to the Sun (which I really
could not without burning up) and flash my torch, the light would take 8.5
minutes to get back.
e would still have to wait three months to see the explosion!
Now you have their attention, a poster of the Southern Cross against a
background of stars, and a composite picture of a Galaxy like ours (as was
published in Sky & Space Magazine in 1994) is useful, as you talk about the
other pointer being 120 light years away, and our sun being just one of the
billions in our Milky Way Galaxy, about two thirds of the way out from the
centre, on one of the spiral arms. Light takes 100,000 years to cross our
Galaxy.
Paul Davies once stated in a lecture a useful observation that impressed me,
and which fits in here quite well, regarding the chance of E.T. encounters. On
Earth we have only been putting out radio signals for 100 years since Marconi
started us off. Even if there were ET beings, they would have to be within 100
light years to detect us, and that does not take in much of our Galaxy, let
alone the Universe.
If the students are not feeling insignificant on the grand scale by now, they will
once you begin to talk about our neighbouring galaxies, the Small Magellanic
Cloud about 100,000 light years away) and the Large Magellanic Cloud (about
300,000 light years away), each containing billions of stars just like our own
Milky Way. Both of these neighbouring galaxies are conveniently visible in our
night skies, near the Southern Cross. And these are just two of an estimated
200 billion galaxies in our expanding Universe!
A WALK THROUGH THE SOLAR SYSTEM or SPACE IS FAR OUT!
INTRODUCTION FOR STUDENTS
Ancient astronomers observed points of light that appeared to move among
the stars, and they called these objects planets, meaning wanderers. They
were named after Roman legends. Jupiter was the king of the gods, Mars the
god of war, Mercury was messenger of the gods, Venus was the god of
beauty, and Saturn (father of Jupiter), was the god of agriculture. They also
observed comets with brilliant tails, and meteors or shooting stars falling from
the sky.
Science moved ahead slowly, and in 1610 Galileo studied and reported on the
moons of Jupiter, with his telescope fashioned for this purpose. Your
binoculars are as powerful as Galileo's telescope was back then, and you will
easily be able to see the four major moons of Jupiter on a clear night when
Jupiter is in the sky.
In 1684 Sir Isaac Newton framed the Law of Universal Gravitation which
explained very simply all of Kepler's observations of planetary motion.
Astronomers continued to look to the skies with better optical telescopes, but
it was not until about 1959 when advancements in rocketry after World War II
allowed us to break free of the Earth's gravity and travel to the Moon and
other planets that we entered the golden age of exploration of our Solar
System. The U.S.A. and Russia sent automated spacecraft to the Moon, and
eventually in July 1969 man set foot on the Moon. Automated spacecraft have
orbited and landed on Venus and Mars, explored the Sun's environment,
observed comets, and made close surveys while flying by Mercury, Jupiter,
Saturn, Uranus and Neptune. These marvels of engineering have enabled us
to better understand the Solar system. Through electronic sensors automated
spacecraft have bought colour and complexion to planets that for centuries
were observed from Earth as fuzzy points of light.
With the launch of the Hubble Space Telescope (HST) in 1990,( and the
subsequent repairs necessary to correct the lenses in 1993) scientists are
now able to gaze way out into our Solar System and beyond without having to
peer through the Earth's atmosphere. The Hubble Space Telescope is now
able to be turned to look at any major event in the Solar System, or the
Universe, to give us a first hand, uninterrupted view. The Shoemaker-Levy 9
comet impact with Jupiter was one such event that awarded scientists views
not dreamt of ten years ago. Not only was the HST able to be pointed towards
Jupiter for a look at the impact, but Galileo was also on its way to Jupiter and
took some spectacular pictures. The knowledge gained from our journeys
through the Solar System has redefined traditional Earth sciences like
geology and meteorology, and given rise to new disciplines like comparative
planetology. By studying the geology of planets, asteroids and comets, and
comparing differences and similarities, we will learn more about the origin and
history of these bodies, and the solar system as a whole.
ANSWER THESE QUESTIONS
1.(a) The Earth is approximately 12, 800 km in diameter. The size (diameter)
of the Moon ( approx 3,200 km in diameter) compared to the Earth. How large
in diameter on our scale?
(b) The Moon is approximately 400,000 km away from the Earth. Our Solar
Scale has the Earth as 1mm diameter, and this represents 12,800 km. How
far away is the Moon from Earth on our scale?
2.It took three days for Apollo 11 to reach the Moon in 1969. If we still had the
technology available, how long would it take to reach Mars?
3.We wouldn't like Venus, and in fact many craft have already been sacrificed
to this awful planet, so where else might we travel in the Solar System?
(a) Mercury? Discuss
(b) Jupiter? Discuss
(c) Others?
4. It takes light 8.5 minutes to reach Earth from the Sun, even though light
travels at 300,000 Km per second. We call this distance 8.5 light minutes.
(a)How many light minutes is Jupiter from the Sun?
(b)Pluto is at the outer most part of our Solar System. How many light minutes
is Pluto from the Sun?
(c)Now use the scale to work out how far away in light years is our nearest
neighbouring solar system containing Proxima Centauri. (This Solar System
contains three suns Proxima Centauri and Alpha Centauri A and B. From
Earth this system looks like one star and is one of the Pointers to the
Southern Cross.)
5. Some people remember the planets by using this saying:
MY VERY ENERGETIC MONKEY JUST SHOWED US NINE PLANETS
List the planets in order from the Sun.
Special Note: Pluto is no longer considered a planet so the acronym is no
longer valid. However it does open up a whole new discussion as to why that
decision was made.
A GUIDE FOR TEACHERS ON THE WORKSHEET FOR STUDENTS:
"A WALK THROUGH THE SOLAR SYSTEM......FURTHER EXCURSIONS"
The accuracy of the mathematics here should not be the most important
feature. Approximations can readily be made on this gigantic scale! The
students will find these distances and times impressive, and all the questions
are intended to emphasise this. Teachers might point out the amazing
achievements that humans have made since the Wright Brothers first took to
the sky less than 100 years ago (1903).
What might the next hundred years bring??
(The real distances are: Diameter of Earth 12,760 km. Moon Diameter is
3,476 km and the distance of the Earth to the Moon is 384,000 km. but
approximates will be easier)
We have more questions and answers if required, but these should keep the
class busy.
ANSWERS TO QUESTIONS
1.(a) The Earth is approximately 12, 800 km in diameter. The size (diameter) of the Moon (
approx 3,200 km in diameter) compared to the Earth. How large in diameter on our scale?
Using these approximate diameters we need to divide 12,800 by 3200 . This gives 0.25 and
since the Earth is 1mm on our scale then the moon will be 0.25 mm.
(b) The Moon is approximately 400,000 km away from the Earth. Our Solar Scale has the
Earth as 1mm diameter, and this represents 12,800 km. How far away is the Moon from Earth
on our scale?
If each 1 mm (Earth diameter) is really 12,800 km, then we simply need to find out how many
lots of 12,800 divide into 400,000. Answer is approx. 31. So it is 31 mm away.
2.It took three days for Apollo 11 to reach the Moon in 1969. If we still had the technology
available, how long would it take to reach Mars?
We worked out in question 1 (b) that the moon is approx 31 mm away from Earth, and since
31 mm is close to 33 mm ( about one thirtieth of a metre), then it would have taken 3 days to
travel about one thirtieth of a metre. That means each metre takes 30x3=90 days to cover.
Now on the scale Mars is 6 metres further from the Sun than Earth, so there are 6 times 90
days of travel which comes to 540 days, or approximately 1.5 years.
Of course lighter craft can achieve higher speeds and the spacecraft can reach Mars in less
than a year. We need to wait for the 365 day orbit of Earth to line up with the 687 day orbit of
Mars, so that we cover the least possible distance in space. This opportunity occurs about
every 26 months.
3.We wouldn't like Venus, and in fact many craft have already been sacrificed to this awful
planet, so where else might we travel in the Solar System?
(a) Mercury? Discuss
(b) Jupiter? Discuss
(c) Others?
Students should consider things like size, distance from the Earth (and from the Sun),
temperatures, atmospheres, whether the planet has a solid surface etc. All of this can be
researched readily through Computer Software, the Internet or the library.
4.It takes light 8.5 minutes to reach Earth from the Sun, even though light travels at 300,000
Km per second. We call this distance 8.5 light minutes.
(a)How many light minutes is Jupiter from the Sun?
If light reaches us in 8.5 minutes from the Sun, ( we are 12m away on our Scale of the Solar
System) and Jupiter is about 60 metres (really 62m) then since Jupiter is 5 lots of 12(=60)
then 5 times 8.5 minutes =42.5 minutes. That is 42.5 light minutes.
(b)Pluto is at the outer most part of our Solar System. How many light minutes is Pluto from
the Sun?
480 divided by 12 gives 40 times the Earth's orbit. Multiply 40 by 8.5 minutes equals
340 light minutes, or 5 hours and 40 minutes.
(c)Now use the scale to work out how far away in light years is our nearest neighbouring solar
system containing Proxima Centauri. (This Solar System contains three suns Proxima
Centauri and Alpha Centauri A and B. From Earth this system looks like one star and is one
of the Pointers to the Southern Cross.)
Divide 3200 by 12 to find out the number of lots of 8.5 minutes we have to multiply by.
This comes to approximately 4.3 light years. Now think about that! Light leaves our Sun and
passes Earth 8.5 minutes later, leaves the Solar System at Pluto after only 5.5 hours, but will
not encounter another thing for another 4.3 years. Wouldn't that be a boring trip??
5. Some people remember the planets by using this saying:
MY VERY ENERGETIC MONKEY JUST SHOWED US NINE PLANETS
List the planets in order from the Sun.
EXTENSION QUESTION
Use the Internet, library or other sources to find out which spacecraft have visited other
planets, from which country they came, how many have landed and what each mission found
out!