
SILO 3.2 (DRAFT) Year 3, Term 2: Satellites Focus: Gravity Scope and sequence: Gravity, Heliocentric model
Learning intention: Students explore night and day and seasonal changes in relation to orbiting bodies and then apply this knowledge to global communications and satellites.
Overview: The Earth is a satellite which rotates on its own axis each day while revolving around the Sun each year. Students will come to see how this rotation causes us to experience night and day. The angle of the Earth's rotation combined with its revolution around the Sun is why we experience different seasons throughout the year. This unit also looks at mechanical satellites which are used for global communications.
NSW Syllabus	Australian Curriculum (version 9.0)
"A student describes how contact and non-contact forces affect an object’s motion." (ST2-9PW-ST) "A student investigates regular changes caused by interactions between the Earth and the Sun, and changes to the Earth’s surface." (ST2-10ES-S)	"Students learn to describe the movement of Earth and other planets relative to the sun and model how Earth’s tilt, rotation on its axis and revolution around the sun relate to cyclic observable phenomena, including variable day and night length." (AC9S6U02)

Introduction to the topic

A satellite is a moon, planet or machine that orbits a larger object such as a planet or star. 'Orbit' is a revolution around another object as distinct from rotation which involves spinning around its own axis. The following video (1:50) explains all of this in relation to night and day.

Communication satellites

This animation (0:56) was made by a student in Year 6 and it introduces some of the basics about how communication satellites work.

Gravity

This video (0:47) shows an experiment conducted on the Moon during the Apollo 15 voyage in 1971.

Anti-gravity creature activity

The 'anti-gravity creature' appears to defy gravity by climbing up the string rather than sliding down.This activity works well with students of all ages.

Materials:

Cardboard
String (must be rough such as common brown string)
Straws (McDonalds thick shake straws work well as they have a wider diameter)
Weights (marbles work well)
Tape (masking tape or magic tape are best because they can be torn easily which can save time)
Icy pole sticks

Tools:

Scissors

Procedure:

Draw a creature with two raised arms, one in each corner. Ensure that generous proportions are used as the creature needs to have a strong frame.
Cut two pieces of straw which are wider than the tape so that no tape protrudes over the ends of the straws.
Attach the straws to the back of the cardboard at 45 degree angles as shown in the diagram above.
Cut out your creature using scissors.
Tape the string to the icy pole stick. It is recommended to use three pieces of tape, one in the middle and one on each side of the stick.
Thread the string through the straws.
Attach marbles to each end of the string.

Tips:

Tape can be put over the straws before cutting each straw piece to ensure that they are wide enough.
Young children might require assistance attaching their straws correctly. This is the most critical part as the angle is very important.
Masking tape is useful as the straws can be easily removed, readjusted and reattached if necessary, even after the string has been threaded.
There are no special knots or tricks required to attach the string to the marbles. Just touch each end of the string to a marble and wrap tape around it.

What happens if you remove the marbles by cutting them off? Why does this happen?

Sir Isaac Newton used a cannonball analogy to explain the orbit of the Moon around the Earth as shown in the image below.

Brian Brondel - Own work, CC BY-SA 3.0,

Why doesn't gravity cause the Moon to collide with the Earth?

Rocket science

Rocket science can refer to the engineering behind the construction of rockets or the chemical processes involved in rocket propulsion. We will look briefly at both in this section starting with rocket fuel which often consists of mixing liquid hydrogen with liquid oxygen.

Technically, the following video does not require a risk assessment because we are not suggesting that you attempt to replicate any of the experiments in this video.
One of the presenters also says towards the end of the video, "Do not try this at home".
Do not play with matches.

This video (3:25) does not mention rocket fuel but liquid hydrogen and liquid oxygen are still used in many rockets today and were used in many of the most famous space missions.

The Smithsonian Build the rocket book (Graham, 2017) contains 88 cardboard model pieces to construct a Saturn V rocket. Although The SILO Project does not officially endorse any STEM resources, this product is recommended as it is a fun way to get a feel for how the different sections of a rocket function together. With or without a hard copy of this book, look at the picture of the assembled model on the left of the book cover and notice how the sections get smaller as you look up from the bottom to the top sections of the rocket. Based on this comparison, consider the following three questions.

Is it easier for a rocket to lift off from the Earth or from the Moon?
How can you tell?
Why is this?

Frame of reference

Direction is relative as shown in this video (0:47) where clockwise and anti-clockwise depend on your frame of reference.

Sundials

In the animated GIF below you can see that the movement in in a clockwise direction.

By Willow W - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=3397590

The following photo has the numbers going anticlockwise. Look carefully for other details in the photo to explain why this might be the case. (Hint: Think in terms of geography.)

https://en.wikipedia.org/wiki/Sundial#/media/File:Sundial_in_Supreme_Court_Gardens,_Perth.jpg

The Coriolis effect

The Coriolis effect describes the pattern of deflection taken by objects not firmly connected to the ground as they travel long distances. This explains why tornadoes spin in different directions in the Northern and Southern Hemispheres as the Earth is moving much faster at the equator than at the poles.

The following video (1:20) involves placing a glue stick on a spinning 'Lazy Susan' to demonstrate the Coriolis effect.

(This idea was from a podcast featuring the award-winning science teacher Brett Crawford, the Lead Science teacher at Warrigal Road State School in Brisbane. Brett received the Prime Minister’s Prize for Excellence in Science teaching. https://www.teachermagazine.com.au/articles/school-improvement-episode-18-supporting-primary-science-teachers?utm_source=Twitter&utm_medium=social%20media&utm_content=social)

Time zones

Seasons

Life is different at the poles

(Jacobs & Robin, 2016, p. 273)

Australian indigenous knowledge

The arrangement of these rocks on Wadawurrung country mirrors the changing position of the setting Sun throughout the year.

https://www.bbc.com/news/magazine-15098959

The Heliocentric model

The Heliocentric model is the idea that the Earth revolves around the Sun (as opposed to the Geocentric model where the Sun revolves around the Earth). The Heliocentric model was very controversial during the Renaissance (15th and 16th centuries) and was a key ingredient in the Scientific revolution. However, the following video (2:16) featuring Eratosthenes (276 BCE – 194 BCE) shows how this idea was discussed much earlier.