K1 & K2

Kepler's 1st and 2nd Laws

• Orbits are NOT perfect circles

• Orbits are Elliptical

• One focus point in a planet's orbit is always the sun.

• The second focus point is a mathematically calculated spot in space.​

Kepler's 1st Law

• Eccentricity is the measure of how elliptical an orbit is.

• Always a value between 0-1

  • 0 = ​perfect circle

  • 1 = flat line

​

Calculating Eccentricity Equation:​

Calculating Eccentricity​

You will need a calculator for a few questions in this next section!

Multiple Choice

The path a planet travels around the sun is called its 

• orbit
• ellipse
• barycenter
• precession

Multiple Choice

Planets orbit the Sun in a shape called a(n)

• circle
• ellipse
• focus
• perihelion

Multiple Choice

An ellipse is drawn around two points called

• aphelion
• perihelion
• foci
• axis

Multiple Choice

When a planet orbits the Sun, one of the foci of the elliptical orbit is 

• the axis
• the perihelion
• the center
• the Sun

Multiple Choice

What has an eccentricity of zero

• a straight line
• a large ellipse
• a circle
• a small ellipse

Multiple Choice

Which diagram in the image shows a planet with the LEAST eccentric orbit?

• A

• B

• C

• D

Multiple Choice

Which diagram in the image shows a planet with the MOST eccentric orbit?

• A

• B

• C

• D

Fill in the Blank

The distance between foci is 6.0. The length of major axis is 10.5. What is the eccentricity to the nearest thousandth?

Fill in the Blank

The distance between foci is 2.0. The length of major axis is 10.0. What is the eccentricity to the nearest thousandth?

Observe the velocity of this planet in orbit. What do you notice?

Some text here about the topic of discussion

States that a planet speeds up as it gets closer to the Sun, and slows down as it moves farther away.

​

• This is due to the gravitational attraction increasing as the planet approaches the sun

  ​

• This causes velocity to also increase.

​

Kepler's Second Law

Multiple Choice

Kepler's 2nd Law deals with 

• the shape of the planets' orbits
• the speed/area the planet travels 
• the length of time it takes the planet to orbit the sun

Multiple Choice

Kepler's second law states that _________.

• a planet moves faster when closer to the Sun

• planets close to the Sun have shorter periods than those farther away

• the Sun is at the center of planetary orbits

• slowly moving planets are close to the Sun

Multiple Choice

Where is the planet moving faster

• Position A to B
• Position B to C
• Position H to I
• Position I to J

Multiple Choice

A planet moves __________ when it is farthest from the sun.

• faster
• slower

Multiple Choice

A planet moves fastest during its orbit around the Sun when...

• it is closest to the sun and gravity has a stronger pull

• it is farthest from the sun and gravity has a stronger pull

• it is closest to the sun and gravity has a weak pull

• it is farthest from the sun and gravity has a weak pull

There is one more law of Planetary Motion!