Download What happened to Pluto? - School

What happened to Pluto?
Teachers’ notes
What’s it all about
Pluto lost its planetary status when scientists redefined what a makes a planet. Advances in
technology results in new knowledge and often scientists have to review and question their
original thoughts.
In this activity children learn about the scientific method. They use evidence to decide
whether or not Pluto is a planet. They develop the idea of how science works to role-play their
explanation in an assembly. This activity is a cross-phase activity.
Where it fits
Science:
QCA Unit 5E: Earth, Sun and Moon



that the Sun, Earth and Moon are approximately spherical
that the Earth takes a year to make one complete orbit of the Sun
that the Moon takes approximately 28 days to orbit the Earth
Scientific enquiry



use observations or other data to draw conclusions
decide whether any of these conclusions agree with any prediction made
use scientific knowledge and understanding to explain conclusions
What children will learn:

that it is important to test ideas using evidence
Children will demonstrate this by completing the task on page 3 successfully

that data can be used to draw conclusions and agree or disagree with a prediction
Children will demonstrate this by completing the task on page 3 successfully

that Pluto is not defined as a planet under the new definition
Children will demonstrate this by completing the task on page 3 successfully
What you need to do
Introducing the activity

-
Display page 1 through a projector or as an OHT. Generate discussion about the
number of planets in the Solar System
How many planets are there?
What has happened recently to change this?
What do you know about the planets?
Do you think that scientists can change their ideas? When would they do so?
1
Leading the main activity

Display page 2 through a projector or as an OHT. Ensure that all the children are
clear about the four properties that define a planet:
1. It must orbit the Sun
2. It must be spherical in shape
3. It must not be a satellite (e.g. a moon of another planet)
4. It must clear its orbit (i.e. it must be the biggest object in its orbit by far)
Children can role-play the parts of the ‘planets’ and the responder who tells them why they
are not planets. This can be extended so that children can take the role of the Sun, the Earth
and the Moon and ask ‘am I a planet?’ The rest of the class can respond and give their
reasons.

Display page 3 through a projector or as an OHT. Print off copies for the children.
Provide scissors for the children to cut out the cards. They need to sort out the cards
into three piles
1. Planet
2. Dwarf planet
3. Other
The children need to understand that if the ‘planet’ orbits the Sun, is spherical, is not
a satellite but is also NOT the biggest body in its orbit then it is classed as a dwarf
planet.
Ask the children to work in pairs to classify their cards. Finally bring the class
together to discuss their findings. What is their conclusion? Now they need to decide
how they will role-play this explanation in assembly. They need to take the parts of
the prospective planets, perhaps using those on the cards plus additional ones from
the Solar System or maybe others they have heard of. They will need a ‘scientist’ to
narrate. A group of children need to be the International Astronomical Union (IAU)
discussing how to define a planet.
Extension Ideas . . . Cross Curricular Links
How do we know the Earth is a sphere? (Science):
What part have scientists played in determining the shape of the Earth? What
evidence do we have to say it is spherical?
Pluto is no longer a planet (Literacy):
In August 2006 the news that Pluto was no longer classed as a planet caused ripples
around the world. Prepare the text for a brief television news report about the issue.
Circumnavigating the globe (History):
Who was the first to sail around the world? What impact did this have? What were
the problems and what were the advantages?
2
Assessment for Learning: Smart Grid
Thumbs Up
We were
great at the
task
because…
Thumbs
Sideways
We were
good at the
task
because…
Thumbs
Down
We were OK
at the task
because…
we defined Pluto as
a dwarf planet
because it did not
clear its orbit
we classified the
cards correctly as
‘Planet, ‘Dwarf
planet’ and ‘Other’
we could support
our decisions by
making reference to
the new planet
definition
we identified which
of the cards were
planets under the
new definition
we identified that the
Sun, Moon and
Earth are spherical
Next time we will…
we showed that the
moon is not a planet
because it orbits the
Earth
we . . .
Smart Grids were devised by the Centre for Science Education
Science at your fingertips
Why was Pluto a planet in the first place?
The word "planet" originally described "wanderers" that were known only as moving
lights in the sky. Recent discoveries meant that there was a need for a new definition,
which was made using currently available scientific information. Contemporary
observations are changing our understanding of planetary systems, so our
nomenclature for objects must reflect our current understanding.
Why is Pluto so interesting?
Experts have been divided over whether Pluto - further away and considerably
smaller than the eight other planets in our Solar System - deserves the title. Since
3
the early 1990s, astronomers have found several other objects of comparable size to
Pluto in an outer region of the Solar System called the Kuiper Belt. Some
astronomers believe Pluto belongs with this population of small, icy "TransNeptunians", not with the objects we call planets. The situation changed with the
discovery of 2003 UB313 by Professor Mike Brown and colleagues at the California
Institute of Technology (Caltech). After being measured with the Hubble Space
Telescope, it was shown to be some 3,000km (1,864 miles) in diameter, making it
larger than the ninth planet.
Why did the International Astronomical Association decide to redefine the planets?
In latter years more and more objects have been discovered that could be classified
as new planets. It is necessary to redefine what is meant by ‘planet’ so that we don’t
have an overly complicated model of our Solar System.
What does ‘clearing the orbit’ mean?
If a planet clears its orbit it means that not only is that planet the largest object in its
orbit but that it is more massive then any of the other objects in its orbit put together.
Since Pluto’s orbit is elliptical it crosses Neptune’s orbit and so since Neptune is
much larger (49530km), Pluto does not clear its orbit.
Web links
Bob the Alien’s Tour of the Solar System
http://www.bobthealien.co.uk/index2.htm
Facts and interactives about planets, comets, asteroids and stars
The Register
http://www.theregister.co.uk/2006/08/24/pluto_demoted/
Planet status and definition of a planet
International Astronomical Union
http://www.iau2006.org/mirror/www.iau.org/iau0603/index.html
Status of Pluto
Liverpool Museums
http://www.liverpoolmuseums.org.uk/nof/sun/san1.html
Facts and interactives about the Sun and Earth and ideas for activities
Astronomy Blog
http://www.strudel.org.uk/blog/astro/000508.shtml
Planets: questions answered
BBC Schools
http://www.bbc.co.uk/schools/scienceclips/teachersresources/ages9_10/tr_earth_sun_
moon_cr.shtml
Schools science clips - Science topics age 9-10 Earth, Sun and Moon
4