1. Our Solar System!

2. First Sighting of Planets
Ancient Greeks noticed that ____________ objects appeared to wander through the ______________.
These were the 5 planets you can see without binoculars or telescopes:
Mercury, Venus, Mars, Jupiter, and Saturn
The ancient Greeks thought that these objects were special because they were not ____________ against the background sky, like the stars appear to be.
Planet: from the Greek word for wanderer.

3. Criteria to be a Planet An object is a ____________ if it:
orbits around one or more ___________
is not a __________ itself
is _____________
does not share its _____________ with another object

4. Components of our Solar System
The __________________
The _________________
Other smaller ________________ _______________.

5. Models of the Solar System
Around year
Greek astronomer Ptolemy came up with a model of the solar system
It was believed that ___________ was the center of all planetary motion.
Planets and sun travelled in perfect ________________ around Earth.
This is called the ______________________ model
Geo means ________________.
In the 1500s...
Polish astronomer Copernicus presented new observations
Came up with the _________________________ model.
Helio means _______________.
Sun is in the ____________________ of the solar system
Planets orbit the sun in perfect _____________________________.
Early 1600s...
German astronomer Johannes Kepler revised the model
Demonstrated that orbits of the planets are __________________.

6. Classification of the Planets
Inner Planets
Also called __________________ planets.
Mercury, Venus, Earth, and Mars
Outer Planets
Also called _________________________
Jupiter, Saturn, Uranus, Neptune

7. Apparent Retrograde Motion
Watch the video “Mercury retrograde, explained without astrology” by Vox:
Answer the following questions:
Planets on the inside of the solar system move _____________________ than the planets on the outside of the solar system, but they all go in the same _______________.
Apparent Retrograde Motion is when the planets ___________________ to temporarily change the direction of their __________________.
The illusion unfolds over a matter of _____________ or _____________________.
Sketch the shape of a retrograde illusion:

8. This illusion occurs when we ____________ an outer planet like we do with Mars around every _____________ years, or when an inner planet _____________ Earth like Mercury does every _________ months or so.
Why is it hard to capture the apparent retrograde motion of Mercury and Venus?
Would you say that the diagrams of the solar system are accurate? Why or why not?

9. Apparent Retrograde motion of
Mars and Mercury

10. Distances between Planets
The distance between planets is so huge that astronomers created a unit for measuring distances in the solar system
The Astronomical Unit (AU)
Equal to the average distance between the ____________ and the _______________.
Equals about __________________ million kilometres.
By definition, Earth is _______ from the Sun.
The average distance between the Sun and an object orbiting the Sun is called the ____________________________.

11. Homework
Page 292, #1, 2
Page 296, #1, 2, 4, 5 (use the table you already made), 7, 8.
Use pg to complete the table THE PLANETS OF OUR SOLOR SYSTEM.