Pg. 134 Feb. 4, 2013 Focus: Gravity and the Solar System Objective: 6.E.1, analyze the affect of gravitational pull and how it changes depending on the distance and mass of the object EQ: What is gravitational pull and how does it affect our solar system? HW: lesson review questions Warm Up: self evaluation

LAST PICTURE IS GLOBULAR CLUSTER 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? Question answers: Earth – Moon Distance 384.4x103km. Is it really made of green cheese? Or something more geological? Planets are “wandering stars.” Comets are bad omens? Or something else? Those “fixed” pin-points of light? Do they really fall down to Earth as “Shooting Stars?” What is the closest star? (Anyone?) We are setting foot on a grand adventure to expand our knowledge about these and other astronomical objects. Consider yourself explorers hunting for the treasures of the universe. We are “prospecting” the heavens to uncover its many facets. LAST PICTURE IS GLOBULAR CLUSTER

Our Solar System From http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2167 This is a montage of planetary images taken by spacecraft. Included are (from top to bottom) Mercury, Venus, Earth (and Moon), Mars, Jupiter, Saturn,Uranus and Neptune. The spacecraft responsible for these images are as follows: Mercury was photographed by Mariner 10. Venus was imaged by the Magellan spacecraft's radar. Earth and its Moon were photographed by Galileo. Mars Global Surveyor took the image of Mars. Jupiter was photographed by Cassini as it traveled to Saturn. Saturn, Uranus and Neptune images were taken by the twin Voyager spacecraft. Pluto is not shown. No spacecraft has visited Pluto and it is too small and distant for good photography. The inner planets - Mercury, Venus, Earth, Moon, and Mars - are roughly to scale to each other; the outer planets - Jupiter, Saturn, Uranus, and Neptune - are roughly to scale to each other. But the actual size differences between the inner and outer planets is not to scale. Actual diameters: Sun 1,390,000 km Mercury 4,879 km Venus 12,104 km Earth 12,756 km Moon 3,475 km Mars 6,794 km Jupiter 142.984 km Saturn 120,536 km Uranus 51,118 km Neptune 49,528 km Pluto 2,390 km 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” Rocky Dense Metal 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. Information on Pluto at http://www.nineplanets.org/pluto.html

Kuiper Belt Disk of debris at the edge of our Solar System Pluto is a KB Object Image from http://hubblesite.org/newscenter/archive/releases/1995/26/image/b/format/web/ Information from The Nine Planets: http://www.nineplanets.org/kboc.html

The Solar System Sun

The Solar System Sun Mercury

The Solar System Sun Mercury Venus

The Solar System Sun Earth Mercury Venus

The Solar System Sun Mars Mercury Venus Earth

The Solar System Sun Jupiter Mars Mercury Venus Earth

The Solar System Sun Saturn Jupiter Mars Mercury Venus Earth

The Solar System Sun Uranus Jupiter Saturn Mars Mercury Venus Earth

My Very Excellent Mother Just Served Us Nachos. The Solar System Sun Neptune Jupiter Saturn Uranus Mars Mercury Venus Earth My Very Excellent Mother Just Served Us Nachos.

http://video. nationalgeographic 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 G R A V I T Y

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 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. NSF North Mississippi GK-8

TICKET OUT 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?