The planets 12/1/14

The planets What is the difference between the Terrestrial and the Jovian Planets? Remember: Terrestrial Planets Mercury, Venus, Earth, Mars Small Close to the Sun Dense/Solid Jovian Planets Jupiter, Saturn, Uranus, Neptune Large Far from the Sun Gas/Not dense

Motions of the Planets speeds 225 rotate revolve Each of the 8 planets of our Solar System are constantly moving in many different directions and __________ First, they are moving with the Solar System around the Milky Way Galaxy in periods of about _______ million years! They also __________ around an imaginary axis and _________ around the Sun speeds 225 rotate revolve

Motions of the Planets

Planet Rotation rotation period day Planets spin on an imaginary axis in a motion called __________ The _________ of rotation is the amount of time it takes for a planet to make one spin around its axis – this determines the length of the planets ______ rotation period day

Planet Rotation

Planets rotation Using the Solar System Data Table in your ESRT, answer the following questions about the rotations of the planets: What is the length of a day on Mars? ________________________ Which planet has the shortest period of rotation? _____________ What is the exact length of rotation for the Earth? _____________________ How long is one day on Saturn? ____________________________ Which planet has the longest period of rotation? ______________

Geocentric vs heliocentric Models What is the difference between the Heliocentric and the Geocentric Models of the Solar System? “Geo” means Earth  Earth centered model “Helio” means Sun  Sun centered model https://www.youtube.com/watch?v=iiBIFlvu- X0

Geocentric Model

Heliocentric Model

Initial Proof Venus goes through phases just like our moon!

Initial Proof

Planet Revolution revolution orbit counterclockwise year A planet’s ____________ is its movement around the Sun in a path called an _______ The planets revolve around the Sun in a ______________________ direction The amount of time it takes a planet to revolve around the Sun is considered that planets _______ orbit counterclockwise year

Planet Revolution

Planet revolution Using the Solar System Data Table in your ESRT, answer the following questions about the revolutions of the planets: How long does it take the Earth to revolve around the Sun? _________________________ What do we do to account for the lack of a full day in our revolution? _______________________________________ Before looking at your Reference Table – which planet would you expect to have the shortest period of revolution? Why? Which planet does have the shortest period of revolution? __________________ Before looking at your Reference Table – which planet would you expect to have the longest period of revolution? Why? Which planet has the longest period of revolution? __________________

Johannes Kepler Kepler was a 17th century German mathematician, astronomer, and physicist He was the first to discover that planets do not orbit in perfect circles around the Sun

Kepler’s Laws of motion http://www.bing.com/videos/search?q=kepler's+discoveries+about+ellipses&qs=PA& sk=OS1&FORM=QBVR&pq=keplers%20discov&sc=4- 14&sp=2&qs=PA&sk=OS1#view=detail&mid=001C20E3DC9987C16AAE001C20E3DC9987 C16AAE After studying the planets to the point where he almost went insane, Kepler made an incredible discovery that he defined in 3 Laws (we are only going to discuss 2 of them)

Kepler’s 1st Law of motion ellipse The orbit of a planet is an __________ with the Sun at one of the two ______ An ellipse is an oval shaped orbit foci

Kepler’s 2nd Law of motion speed A planet’s orbit will change _________ depending on its distance from the Sun When the planet is closest to the Sun, it will be moving _____ When the planet is farthest from the Sun, it will be moving _______ fast slow

Kepler’s 2nd law of motion PLANETS MOVE FASTER CLOSER TO THE SUN!

Let’s look at the elliptical orbit of a planet… Major Axis Planet Sun Minor Axis Foci The major axis is the longer line that cuts through the two foci!

Eccentricity eccentricity eccentric The ________________ of an ellipse is the degree of “ovalness” – or how oval-shaped it is The more “flattened” the orbit is, the more _____________ it is eccentric

Eccentricity Eccentricity is a measured value that always falls between the numbers __ and __ A perfect circle has an eccentricity of _____ What do you think the eccentricity of a straight line would be? 1 zero

Eccentricity Formula Eccentricity of ellipse = 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑓𝑜𝑐𝑖 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑚𝑎𝑗𝑜𝑟 𝑎𝑥𝑖𝑠 Distance between foci Length of major axis

Eccentricity formula Determine the eccentricity of the following ellipse: 3.578 cm 5.897 cm

Eccentricity of Planetary Orbits Using the Solar System Data Table in your ESRT, answer the following questions about the eccentricity of the planetary orbits: What is the eccentricity of Earth’s orbit? ____________________ Which planet has an orbit closest to a perfect circle? __________________ Which planet has the most eccentric orbit? __________________ What is the eccentricity of the moon’s orbit around the Earth? ___________________________

Inertia and Gravity inertia motion speed The planets stay in their orbits because of a balance of two things: _________ and gravity Inertia is the concept that an object at rest stays at rest and an object in motion stays in motion unless acted on by another force Inertia acts on the planets by maintaining the _________ and ________ at which they revolve However, the force of gravity affects this motion! inertia motion speed

Inertia and Gravitation attractive Gravitation is the ____________ force that exists between two objects The gravitation force depends on two things: The ____________ between the objects The __________ of the two objects distance masses

Gravitational Force higher The larger the object, the _________ its gravitational pull

Gravitational Force higher The closer two objects are together, the _________ the gravitational pull higher

Inertia and Gravitation So this is why planets move faster when they are revolving closer to the Sun and slower when they are revolving far from the Sun The Sun is pulling them in toward it causing the planet to move faster!