1. Earth orbits the Sun following Kepler’s 3 laws of planetary motion
The path of each planet around the Sun is an ellipse
Equal areas are covered in equal time
The length of time it takes a planet to orbit the Sun is proportional to its distance from the Sun

2. Kepler (1571-1630) came up with these scientific laws and they are still used in Astronomy today!

3. 1st Law: Law of Ellipses
The paths of the planets around the sun are elliptical in shape with the center of the sun being located at one focus
The shape of the ellipse is determined by the location of the two focus points!

4. 2nd Law: Law of Equal Areas
This law states that an imaginary line from the sun to a planet sweeps out equal areas in equal time intervals

5. Kepler’s 2nd Law of Planetary Motion

6. Are they the SAME?
The short wide glass is holding the SAME amount of water as the tall skinny glass!

7. 1st Law: Law of Ellipses
The paths of the planets around the sun are elliptical in shape with the center of the sun being located at one focus
The shape of the ellipse is determined by the location of the two focus points!

8. 2nd Law: Law of Equal Areas
This law states that an imaginary line from the sun to a planet sweeps out equal areas in equal time intervals

9. Kepler’s 2nd Law of Planetary Motion

10. Are they the SAME?
The short wide glass is holding the SAME amount of water as the tall skinny glass!

11. Planet moves FASTER in orbit when CLOSE to the SUN, and SLOWER in orbit when FAR FROM the SUN
WHY?
GRAVITATIONAL PULL

12. The closer a planet is to the sun, the FASTER it orbits around it!!
Kepler’s 3rd Law
The further the planet is from the Sun, the LONGER it will take for the planet to orbit the Sun.
The closer a planet is to the sun, the FASTER it orbits around it!!
Mercury – 88 days
Venus – 225 days
Mars – 687 days
Jupiter – 4331 days
Pluto – 90,582 days or 248 years!!

13. Kepler’s Three Laws of Planetary Motion
(A Summary)
Each planet takes an elliptical path around the sun
Planets travel faster when they are close to the sun and slower when they are farther away from the sun
3. The amount of time needed for a planet to revolve around the sun is proportional to the planet’s distance from the sun

14. End of Day 2

15. Precession
The direction the axis of a planet is pointing in will change, but the tilt will not change.
This will change the stars near the pole but will not change the seasons (as long as the angle of the tilt, 23.5 in the case of Earth, stays the same)

16. Precession Animation

17. The Sun
The sun is at the center of our solar system. You may have learned that the planets orbit the sun, but in fact the Sun and planets orbit each other around the barycenter.

18. Barycenter
A barycenter is the point between two objects where they balance each other
For example, the middle balancing point on a scale.

20. Barycenter Animation

21. Nutation Nutation happens when the axis of a planet starts to wobble
The angle of the axis will change during nutation ½ degree one direction or the other
Nutation happens over the course of 18 years
Nutation is a direct result of the moon (or moons) of a planet

23. Sun consumes 600 million tons of H each second!
The Sun
Our Sun and all other stars produce their energy by a process called nuclear fusion
Fusion is when hydrogen atoms collide to make a Helium atom; this releases lots of energy
Sun consumes 600 million tons of H each second!

24. What is the Difference between Fusion and Fission?
Fission is the opposite idea…instead of building bigger atoms, you are breaking atoms apart
Nuclear Power Plants like McGuire Nuclear Station in Huntersville do this with Uranium

25. Fusion puts things TOGETHER
Fission splits things APART

26. Energy Produced by the Sun
Most of what astronomers know about our universe is known from studying the light emitted from distant sources

27. Electromagnetic Spectrum
Visible light is just a small portion of the energy emitted by stars…what else is there?

28. Gamma Rays - are produced by violent nuclear explosions in space and are absorbed by our atmosphere…good thing, they are deadly to human cells!
X-rays - are also absorbed by Earth’s atmosphere, so NASA has to put x-ray telescopes into space
UV Rays - are mostly blocked by the ozone layer, but some can get through and cause sunburns!
Infrared Rays - cause the heat we feel from sunlight
Microwaves - easily move through atmosphere and are used in with satellites and GPS
Radio Waves - are used with huge telescopes to learn about the structure, composition, and motion of objects in space

29. The Electromagnetic Spectrum