
SILO 3.2 (DRAFT) Year 3, Term 2: Satellites Focus: Angles Scope and sequence: 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 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

The central idea which runs throughout this unit is that a satellite is a moon, planet or machine that orbits 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.

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?

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)

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.