What do you notice about the Orbit of the Planet’s compared to the Comet’s?

Aim: Describe Kepler’s

Three Laws of Planetary Motion

(eccentricity)

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Which lane will Finish First?Which lane has a shorter distance to travel?

First Law: The planets move in elliptical orbits with the Sun at one focus.

Planet

Sun Foci

What is an ellipse?An ellipse is a closed curve around two

fixed points called foci.Eccentricity- measures how stretched

out, NOT circular an orbit is.Eccentricity= d (distance btwn foci)

L (length of Major axis)

Label the following:distance between foci (d) and the

Length of Major axis (L)d

Planet

Sun Foci

L

E= 5.2cm = 0.419 12.4cm

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Which planet has the roundest orbit?

Which one is the most ellongated?

Which planet moves fastest?

Which one moves the slowest

Which eccentricity is closest to Uranus?

Find the eccentricity of the following Distance between Foci = 8.7 cm

Length of Major Axis 10.2 cm

Is this orbit more or less eccentric as compared to the Earth?

1. Describe the relationship between eccentricity of an ellipse and the shape of a planet’s orbit

2. State the relationship between distance between foci and eccentricity of orbit.

Use the ESRTp.15 Solar System Data Chart to answer the following:

Planet with the Least eccentric orbit-

Planet with the Most eccentric orbit-Venus – 0.007 (Most nearly Circular)

Mercury – 0.206State the range for eccentricity?

0.000 – 1.000Circle - Line

Second Law-Law of equal areas. A line from the Sun to any planet sweeps out equal areas in equal time.

SUNSUN

X-Y = 30 daysA-B = 30 daysA1=A2

A

XB

Y

A2A1

1. A planet must travel a longer distance in its orbit from X-Y .

2. For a planet to travel from X-Y and A-B in the same amount of time it must increase its velocity in orbit from X-Y.

3. It is winter in the Northern Hemisphere. The seasons are caused by the Earth’s tilt on axis. The Northern Hemisphere is tilted away from the Sun during our Winter (January).

BA

X

Y

Perihelion-Planet is closest to the Sun

Aphelion- Planet is furthest from the Sun

SUN

Appears BIGGER Closer Perihelion

SMALLER Farther

Aphelion

• Elliptical Orbits Interactive Animation: http://www.windows2universe.org/physical_science/physics/mechanics/orbit/orbit_shape_interactive.html

Solar SystemFill in the data table using your ESRT

Name of Planet Distance from Sun Period of RevolutionMercury 57.9 88 daysVenus 108.2 224.7 daysEarth 149.6 365.26 daysMars 227.9 687 days

Jupiter 778.3 11.86 daysSaturn 1,427 29.46 daysUranus 2,869 84.0 years

Neptune 4,496 164.8 years

Third Law-The further a planet is from the Sun, the longer its period of revolution.

1. Explain how a planet’s distance from the Sun affects its period of Revolution.

Fill in the organizer below:

SUNA C APHELION PERIHELION

Distance From the Sun  Earth’s location on the diagram Season  Apparent Diameter ofthe Sun  Acceleration in Orbit Gravitational Force Kinetic Energy/Potential Energy