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Day 5: The Solar System 8.4
Name ____________________
This first part has students practising reading graphs and classifying objects by characteristics.
It also has the students decide that Pluto should not be considered a planet.
Use the graphs of the characteristics of planetary objects to answer the following questions.
Note: The objects are placed on the graphs in order of their distance from the Sun.
Classifying Planets
1) Use the data about densities to divide the objects into two groups. (Density of water is 1 ____g/ml)
a) Low density ID numbers; 6-13___________________ (density is less than 0.4 g/ml______);
b) High density ID numbers; 1-5__________________
(density is more than 0.7 g/ml ______);
2) Use the data for radii to place the objects into two groups.
a) Small radii ID numbers; 1-5, 10-13________________ (radius is less than1______________);
b) Large radii ID numbers; 6-9____________________
(radius is more than 4______________);
3) Use the data for number of moons to place the objects into two groups.
a) Number of moons ID number; 1-5, 10-13 ___________ (number of moons is less than 2_________);
b) Number of moons ID number: 6-9 ________________ (number of moons is more than 11 _______);
4) Use the data for mass to place the objects into two groups.
a) Small mass ID numbers; ____________________
(mass is less than ____________);
b) Large mass ID numbers: 6-7 or 6-9__________________(mass is more than 20 or 95___________);
5) Use the data for eccentricity (stretched out circle) to place the objects into two groups.
a) Small eccentricity ID numbers; 1-9________________ (eccentricity is less than 0.3___________);
b) Large eccentricity ID numbers; 10-13____________
(eccentricity is more than 1.4___________);
6) Use the data for tilt (out of solar system plane) to place the objects into two groups.
a) Small tilt ID numbers; 1-9_______________________ (tilt is less than 1______________);
b) Large tilt ID numbers; 10-13_______________
(tilt is more than15 ______________);
7) Use your answers to the previous six questions to place the objects into three groups.
a) Groups A: ID numbers 1-5____ Characteristics: small, dense, few moons AKA Rocky Planets
b) Groups B: ID numbers 4-9 ____ Characteristics: large, low density, many moons AKA Gas Giants
c) Groups C: ID numbers 10-13____ Characteristics: small, few moons, eccentric/tilted orbits, AKA
dwarf planets or Kuiper Belt Objects
8) These objects are in order of their distances from the sun. Identify the objects.
1) Mercury
2) Venus
3)
Earth
4) Mars
5) Ceres
6) Jupiter
7)
Saturn
8) Uranus
9) Neptune
10) Pluto
11)
Eris
12) Sedna
13) Quaoar
th
Students will happily start naming the planets in order. However, the 5 one should make them pause.
They will expect it to be Jupiter but it has the wrong characteristics. It is Ceres, the largest object in the
asteroid belt between Mars and Jupiter. It was once considered a planet, but was reclassified when they
found hundreds of other asteroids in a similar orbital radius. The more recent demotion of Pluto from a
planet to a KBO was done for similar reasons - there are about 200 of them and tens of thousands beyond
the Kuiper belt..
9) You have a 10 year-old neighbour who is keen about astronomy, but is upset because Pluto is no longer
considered a planet. Explain to your neighbour why it is no longer a planet.
Pluto was downgraded because several similar objects were found beyond Pluto and we would have to
increase the number of planets that school children memorize. Once Pluto’s moon was found, it was
possible to get a measurement of Pluto’s mass. It was much smaller than expected, less than the Moon.
A Sense of Scale
These questions help the students practise their skills with powers of ten and to start to appreciate that it
is a useful tool. It also helps them realize that space is really empty
Mercury Venus Earth
Mars
Jupiter Saturn Uranus Neptune Pluto
Moon
2.44 x 6.05 x 6.38 x 3.40 x 7.15 x 6.03 x 2.56 x 2.48 x 1.15 x 1.74 x
106
106
106
106
107
107
107
107
106
106
5.79 x 1.08 x 1.49 x 2.28 x 7.78 x 1.43 x 2.87 x 4.50 x 5.91 x 3.84 x
1010
1011
1011
1011
1011
1012
1012
1012
1012
108
The top row gives the radius of the planet and the bottom row gives the radius of its orbit in metres.
10) You are going to make a model of the Moon, Earth and Sun. The Earth will be represented by a ball
that is 6.38 cm in radius. (Have a large supply of spheres to choose from or inflate balloons.)
a) What is the Incredible Shrinking Factor (ISF)? The objects will be __________ times smaller.
A) 100 thousand
B) 1 million
C) 10 million
D) 100 million
D) 6.38 x 106 m/6.38 cm = 106 m/cm = 108 = 100 million m/m.
You can write out all the zeros – especially at the start then point out how the power notation is easier.
b) How big should the moon be at this scale? What could you use?
1.74 x 106m/(108) = 0.0174 m = 1.74 cm. A small bouncy ball or glass ‘boulder’.
c) How big is its orbit? Will it fit in the classroom?
Don’t forget to double the radius. 7.6 x 108/(108) = 7.6 m It may just barely fit diagonally.
d) The Sun has a radius of 6.96 x 108 m. How big should it be? What could you use?
6.96 x 108 m/(108) = 696 cm or 6.96 m! It won’t fit in the room. Perhap a weather balloon.
e) How far away is the sun? Where will you have to put the sun?
Just use the radius. 1.49 x 1011 m/(100 x 106) =1.49 x 103 m = 1.49 km! This is almost at Coxwell.
All of the pictures that you see of the solar system are not to scale!
11) Let’s try a different scale. The Sun will be a sphere with a radius of 6.96 cm =0.0696 m.
This is like a large grapefruit or a ball for lawn bowling – or a small balloon.
a) What is the ISF?
6.96 x 108 m/ 0.0.96 m = 1010 . This 100 times more than the previous version.
b) How big would Jupiter be and what could you use to represent it?
7.15 x 107 /(1010) = 0.00715 m = 7.15 mm. The largest planet could be a glass marble.
Let each group do a calculation with their assigned planet. They will be even smaller..
c) How far away should Jupiter be from the model Sun? Where is that?
7.78 x 1011 /(1010) = 77.8 m. The orbit will not fit in the classroom nor the soccer field!
Let each group do a calculation with their assigned planet and realize that solar system is really empty.
Only Mercury’s orbit can fit in a classroom.
Watch the Known Universe by AMNH https://www.youtube.com/watch?t=28&v=17jymDn0W6U
This video slowly draws back from the Earth. You could stop at 2:16 which shows the orbits of the
planets or continue beyond to give a preview of what is coming up later in the unit. At 3:37 it stops and
then zooms back in.
Textbook Consolidation: Read page 319. Answer questions from Analyze and Evaluate.