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Pg. 134 Feb. 4, 2013Focus: Gravity and the Solar SystemObjective: 6.E.1, analyze the affect of gravitational pull and how it changes depending on the distance and mass of the objectEQ: What is gravitational pull and how does it affect our solar system?HW: lesson review questionsWarm Up: self evaluation
The Journey Resumes! For as long as there
have been humans on earth, we have gazed into the night sky and wondered: How far away is the
moon? What are planets and
comets? What are the stars, and
why do they shine?
Our Solar System
In our solar system, eight planets circle around our Sun. The Sun sits in the middle while the planets travel in circular paths (called orbits) around it.
What is a planet?
A body that orbits a star
Big enough to create its own gravity
Has a round shape
Has its own orbit
Outer Planets
• Large!
• Gases and liquids
• No solid surface
• May have a small solid core
• Tumultuous atmospheres - rapid winds, large storms
• Rotate relatively quickly
Inner Planets“Terrestrial
Planets”RockyDenseMetal cores
(iron)
What about Pluto?Is Pluto a planet?
Why?
No. Pluto is not a planet. Pluto is a dwarf planet, because its orbit overlaps with Neptune. Pluto does not have its own orbit.
Kuiper Belt
Disk of debris at the edge of our Solar System
Pluto is a KB Object
The Solar System
Sun
The Solar System
Sun
Mercury
The Solar System
Sun
MercuryVenus
The Solar System
Sun
Mercury VenusEarth
The Solar System
Sun
Mercury Venus
Earth
Mars
The Solar System
Sun
Mercury Venus
Earth
MarsJupiter
The Solar System
Sun
Mercury Venus
Earth
MarsJupiter Saturn
The Solar System
Sun
Mercury Venus
Earth
MarsJupiter Saturn
Uranus
The Solar System
Sun
Mercury Venus
Earth
MarsJupiter Saturn Uranus Neptune
My Very Excellent Mother Just Served Us Nachos.
http://video.nationalgeographic.com/video/player/science/space-sci/solar-system/solar-system-sci.html
Gravity
Gravity- an attractive force between any two objects, affected by their size and the distance between the two objects.
Definition
Force of attraction between two bodies, proportionate to their two masses and inversely proportionate to the distance between them
So What?
Sun pulls the Earth towards it
GRAV
I
TY
Mass Affects Gravity
The bigger/more mass an object, the higher the gravitational force it exerts.
Gravity on Different Planets
Distance Affects Gravity, too.
The closer two objects are, the higher the gravitational pull they experience.
2 Things Affect Gravity
SIZE/MASS and DISTANCE
The bigger the objects, the more gravity they have.
The closer two objects are, the more gravity they exert on each other.
• http://player.discoveryeducation.com/index.cfm?guidAssetId=5CA3ED81-E88F-44AF-B63B-13450FA9B355
INERTIA
The Moon
• Inertia keeps the moon moving in a straight line (resisting changes to motion).
• Gravity pulls it towards Earth. • Combined, they pull the moon in a circular orbit around the Earth.
• So, the 2 factors that keep the moon orbiting the Earth are gravity and inertia.
Why does the moon have phases?
• The revolution of the Moon around the Earth causes the Moon to appear to have phases.
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Why do the planets revolve around the sun?What would happen without gravity?What is gravitational pull and how does it affect our solar system?
