Download The Solar System: Cosmic encounter with Pluto

Earth and Space Sciences
The Solar System:
Cosmic encounter with
Pluto
The size and nature of our Solar System is truly awe inspiring, and things
are going to get even more exciting once the New Horizons spacecraft
reaches Pluto in 2015. But just how much do you know about the Solar
System?
In this lesson you will investigate the following:
• How did the Solar System form?
• How big is the Solar System?
• How do we measure distances in the Solar System?
• Which has a longer “day”, Mercury or Jupiter?
How do you organise a party in outer space? You planet!
This is a print version of an interactive online lesson.
To sign up for the real thing or for curriculum details
about the lesson go to www.cosmosforschools.com
Introduction: The Solar System
In some ways 1977 was the beginning of the modern world, with the first computers on sale to the public – and the first home
video games. It was also the year that the first Star Wars movie came out. But Earthlings didn't limit space travel to fiction – they also
launched two identical spacecraft to Jupiter and Saturn: Voyagers 1 and 2.
The Voyagers successfully completed their mission making discoveries such as the active volcanoes on Jupiter's moon, Io, and
learning details about Saturn's rings. They had only been made to last five years but were still both going strong, so NASA extended
their mission. Voyager 2 went on to take a look at the two outermost planets, providing us with the first close-up pictures of Uranus
in 1986 and then arriving at Neptune three years later. Even though they move at speeds in the order of 20 kilometres a second it
still takes a while to get anywhere in the Solar System!
It's amazing that 38 years after they were launched the Voyagers are still gathering data and transmitting it back to Earth. As of 2014
they are at the edge of the Solar System and Voyager 1 is now the most distant man-made object in space. Both Voyagers are in a
zone where the Sun's radiation drops off, teaching us about the transition into deep space.
We haven't finished with the Solar System though. In 2006 the New Horizons spacecraft was launched to fly to Pluto. Just because
it's no longer a planet doesn't mean Pluto and its five moons won't deliver some exciting new discoveries. Data starts arriving back
on Earth in January 2015.
Both of the Voyagers carry gold-plated discs with sounds and images portraying the diversity of life and culture on Earth. Why? Just
in case, one day, the spacecraft are found by intelligent aliens. If they can follow the instructions written on the discs they will hear
the sounds of surf and thunder, of birds, whales and other animals, and of greetings in fifty-five human languages. They will hear
music from different human cultures and see pictures of life on Earth.
The Solar System is a huge and complex place with many discoveries to be made. And it is our home.
Read the original Cosmos blog post here.
Left: An illustration of one of the Voyager spacecrafts as it might look right now at the edge of our Solar System. Right:
The curious cover of the gold-plated disc carried by the spacecraft. The markings are instructions on how to use the disc.
Do you think that an alien would understand them?
Question 1
Describe: When New Horizons has finished sending back all its data from Pluto there will be free space on its hard drive. There is
currently a crowd-sourced project to load the drive with messages from Earth, just like the Voyager discs. What sounds and images
would you choose to go onto the 2015 version of the Voyager gold discs? Why?
Gather: The Solar System
Space exploration has provided us with spectacular photographs of the bodies in our Solar System. Left to right: the Sun,
Jupiter and Neptune.
The Solar System
The Voyager and New Horizons spacecrafts were sent on extraordinary missions to explore our Solar System. But what is the Solar
System and how did it come to be?
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Question 1
Question 2
Recall: The nebula that eventually formed our Solar System
was created by the birth of a star.
Recall: The Earth started to form at the centre of a vast spiral of
dust.
True
True
False
False
Question 3
Recall: Type the missing words into the right hand column of the table below.
Our Solar System is approximately ________ light-years from the centre of our
galaxy.
________ are clouds of dust and gas that result when a star explodes.
________ pulls the dust and gas together to form planets and stars.
The outer gas planets of the Solar System are ________, ________, ________ and
________.
The inner rocky planets of the Solar System are ________, ________, ________ and
________.
The estimated lifespan of the Sun is ________ billion years
Although the ignition of the Sun cleared much of the debris in the Solar System, some things other than planets still remained.
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Question 4
Question 5
Recall: The asteroid belt is located between the orbits of
Identify: Which of the following are considered to be part of our
Solar System?
Jupiter and Saturn
The Sun and Earth
Planets
Asteroid belt
Earth and Mars
Milky Way
Mars and Jupiter
The Moon
Sun
Nebulae
All of the above
Did you know?
Did you know that Pluto, that orbits the Sun beyond Neptune, used to be classified as a planet? But in 2006 the International
Astronomical Union changed the definition of a planet and Pluto didn't fit this new definition, so was reclassified as a "dwarf planet".
So far we have explored some of the major bodies that make up our Solar System and how it was formed. But there is another
important piece to this puzzle: everything in the Solar System is moving.
The planets, their moons and the Sun are all moving around each other in elliptical movements called orbits. The Sun, planets and
moons are also all constantly spinning, like a basketball spinning on your finger. But why do they spin?
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Question 6
Construct: Summarise everything that you know and have learned about the Solar System into a graphic organiser. Create your
organiser on paper and upload a photo of it.
Your organiser should include:
the formation of the Solar System
what makes up the Solar System
the motion of bodies in the Solar System.
Process: The Solar System
The Sun and eight planets of the Solar System shown in scale according to their size, but not according to the distance
between them. Can you name all the planets?
Astronomical distances
The distances between objects in space are immense. For instance, the distance between the Sun and Jupiter is 778,547,200 km,
and the nearest star (Proxima Centauri) is approximately 39,900,000,000,000 km away.
The numbers are so big it's difficult for people to grasp them and it's easy to make mistakes with that many zeros! So astronomers
have developed two other units for measuring astronomical distances – one for the Solar System and another for galaxies, stars
and other objects outside the Solar System.
Astronomical unit
In the Solar System astronomers use the "astronomical unit" (AU). One AU is the distance from the Earth to the Sun (149,600,000
km). On this scale Jupiter is about 5 AU from the Sun.
Light-year
A "light-year" is the distance that light travels in one year. One light-year equals 9,460,500,000,000 km. It's a very long way! That
makes Proxima Centauri 4 light-years away.
Question 1
Calculate: In July 2015, when the New Horizons space probe flies past Pluto, the Earth will be 4,920,000,000 km away. Calculate this
distance in AU.
Orbits
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Model of the planets orbiting the Sun. It simply shows which planets are faster or slower than others.
Question 2
Think: The time it takes a planet to complete one orbit is called its orbital period.
Part A: Fill in the empty cells in column 2 with the number of orbits the planets make in the 25-second video.
Part B: Listed below are the actual orbital periods of the eight planets, measured in Earth years and months, but they are out of
order. Put the values into the third column, matching them to the correct planets.
1 year 11 months | 84 years | 3 months | 165 years | 29 years | 7 months | 12 years
Planet (in order from the Sun)
Mercury
Venus
Number of orbits in video (Part A)
7
​5.5
Earth
Mars
1 yr
3.5
Jupiter
Saturn
2
Uranus
Neptune
Orbital period (Part B)
1
Question 3
Planet race: If Mercury, Venus, Earth and Mars are travelling anti-clockwise in the diagram below, show where they will be in six
months. If any of them have completed any orbits, write the number of completed orbits beside the planet's starting position.
For example: the Earth's orbital period is 12 months. So in six months' time it will be half way around its orbit (6 ÷ 12 = 0.5).
Tilt and rotation
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Question 4
Think: The above video shows the angle of tilt and rotational periods of the planets and Pluto.
Part A: Count the number of rotations in the 25 seconds of the video to fill in the empty cells in column 2.
Part B: The rotational period data for Mercury, Jupiter and Neptune has been mixed up. Can you complete the table with the values
listed below?
16 Earth hours | 10 Earth hours | 2 Earth months
Planet
Number of rotations in video (Part A)
Mercury
Barely moves
Venus
Barely moves
Earth
Rotation period (Part B)
8 months
1 day
Mars
11
1 day and 1 hour
28
10.5 hours
Jupiter
Saturn
Uranus
17 hours
Neptune
17
Question 5
Consider: One Earth rotation is equivalent to:
One month
One day
One year
One day and night
One season
Question 6
Reason: Describe one or more of the effects if the Earth's speed of rotation was double what it is.
Question 7
Hypothesise: Describe some of the effects you might see if the Earth's axis of rotation changed to be the same as Uranus's. If this
had always been the case, do you think life would have evolved in the same way it did?
Apply: The Solar System
Experiment: Modelling the Solar System
Part 1: Size model
Background
Most of the representations of the Solar System that you see in textbooks are not to scale. In this exercise you will find out why.
Aim
To create a model of the Sun and the eight planets of the Solar System showing their relative sizes.
Materials
1 fit ball, approximately 700 mm diameter
modelling clay
ruler
Procedure
Calculate the sizes of the planets using the same scale that represents the Sun as the fit ball. Make planets from the modelling
clay using the ruler to check the diameters.
Results
Question 1
The Sun is 1,390,000 km diameter. The fit ball is 700 mm diameter. A simple calculation shows us that in our model 1 mm is
equivalent to approximately 1,986 km (
1,390,000
700
= 1986).
To make things a bit easier we will round up and use the following scale:
1 mm represents 2,000 km
The diameters of all the planets are given in the table below. Using this scale calculate the sizes of all the planets for the model,
and fill in the table. Round to the nearest millimetre.
The calculation for Mercury is worked out for you below:
The diameter of Mercury is 4,880 km. Divide this by 2,000 to give an answer in millimetres.
4, 880
= 2.44
2, 000
Rounding and using a fit ball to represent the Sun, Mercury would be 2 mm in diameter!
Planet
Diameter (km)
Scaled diameter (mm)
Sun
1,390,000
700
Mercury
4,880
2
Venus
12,100
Earth
12,800
Mars
6,790
Jupiter
143,000
Saturn
121,000
Uranus
51,100
Neptune
49,500
Question 2
Use pen and paper to label your planets and upload a photo of them below.
Part 2: Distance model
Aim
To create a model of the Sun and the eight planets of the Solar System showing the relative distances between them.
Materials
modelling clay
9 flags on sticks
open space, e.g. a playing field, 100 m long.
Procedure
1. Calculate the scale you need to use so that the model will fit in a straight line 100 m long.
2. Calculate the diameter of the Sun at that scale and make a ball of the right size to represent the Sun out of the modelling clay.
3. Calculate the distances between the Sun and planets using the same scale and fill in the table below with the values.
4. On the playing field, place the Sun at one end of the 100 m strip and push in a flag beside it.
5. Pace out the distances to each planet and mark the positions with flags.
Note: One very long pace is about one metre.
Question 3
The distance from the Sun to Neptune is 4,500,000,000 km. We need to scale this down to 100 m.
What is the scale we need to use?
Question 4
The Sun is 1,390,000 km diameter. What diameter should your model Sun be using the scale you just calculated?
Question 5
Complete the table below with the distances to each of the planets in the model, using the scale you calculated.
To help make sure you're on track we've put in the distance to Mercury.
Planet
Distance from Sun (km)
Scaled distance (m)
Mercury
57,000,000
1.3
Venus
108,000,000
Earth
150,000,000
Mars
228,000,000
Jupiter
779,000,000
Saturn
1,430,000,000
Uranus
2,880,000,000
Neptune
4,500,000,000
You are now ready to go and make your Solar System distance model!
Results
Question 6
Upload a photograph of your model. Make sure to stand perpendicular to the line of the planets so that you get a good idea of the
distances.
Tip: For the photo, you and your classmates may wish to stand next to the Sun and planets holding signs to indicate what you're standing
next to.
Discussion
Question 7
In the distance model you placed the planets' positions in roughly a straight line. Is this a true representation of the Solar System?
Why or why not.
Question 8
How big would the planets be if you sized them at the correct scale for the distance model?
Question 9
How far away from the fit ball would your model of Neptune be if you used the scale 1 mm = 2,000 km for the distance model?
Career: The Solar System
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Question 1
Research: ​You decide to make it your life's mission to find another Earth-like planet in the Universe -- one that could harbour alien
life. What would be the ideal job to help you succeed in your mission? What would you need to study in order to get the job?
Cosmos Lessons team
Lesson authors: James Driscoll and Deborah Taylor
Education editor: Jim Rountree
​Education director: Daniel Pikler
Image credits: iStock, Kate Patterson MediPics and prose
and Mirela Tufman
Video credits: The Cosmos is Also Within Us, SciShow, Solar
System Videos, Steven Sanders, New York Times