1. Formation of the Universe
Cosmology – the study of the origin properties, processes, and evolution of the universe.

2. The Big Bang Theory
Big bang theory – the theory that states the universe began with a tremendous explosion 13.7 billion years ago.
13.7 billion years ago all the contents of the universe was compressed under extreme pressure, temperature, and density in a very tiny spot.

3. The Big Bang Theory
Everything then suddenly expanded where matter began to come together to form galaxies.

4. The Big Bang Theory

5. A Raisin-Bread Model
Imagine a loaf of raisin bread before it is baked as the bread bakes the raisins begin to move apart.
This concept applies to our current galaxy in which the solar systems are moving apart.

6. Raisin-Bread Model Demonstration

7. Cosmic Background Radiation
Accidentally discovered in 1964 by two scientists using a huge antenna found radiation coming from all directions in space.
It is believed to be the leftovers from the big bang that now covers all of space.

8. Structure of the Universe
Organization of the Universe
Universe is made of galaxies.
Galaxies are made of stars.
Some stars have planetary systems.
Earth is a satellite planet of one star. (The Sun)

9. A Cosmic Repetition

10. Doppler Effect Same thing happens with light:
Definition
How a siren seems higher pitched as it approaches and lower pitched after it passes.
Same thing happens with light:
Redshift- as light moves away, light looks redder.
Blueshift- as light moves toward, light looks bluer.

11. Doppler Effect

12. Doppler Effect

13. An Expanding Universe
After discovering that the universe is made up of many other galaxies like our own.
Edwin Hubble analyzed the light from galaxies and stars to study the general direction that objects in the universe are moving:
Hubble discovered the light from all galaxies except our neighbors are experiencing redshift.
Redshift – occurs when light is moving away from us.

15. A Forever Expanding Universe
Two things could happen to the universe:
One:
After the universe reaches a certain point it could collapse in a reverse “big bang” in which everything would come back together and start over again.

16. A Forever Expanding Universe
Two: the thought of what will happen.
Due to gravity not being strong enough scientist believe the universe will expand forever getting cold and dark as stars burn out.
Long after stars have burned out the universe will continue to expand forever.

17. The Solar Nebula
Nebulas – a large cloud of gas and dust in interstellar space ( The place where stars are born)
Contains all of the ingredients for building planets, moons, and star are found in nebulas.
Made up of mainly hydrogen and helium.

18. Activity “Nebular Theory Model”

19. The Solar nebula So how does a nebula become a planet?
In order to understand this one must understand the two forces that interact in nebulas.
Gravity
Pressure

20. Gravity Pull Matter together
The matter that make up nebulas are held together by gravity.
Due to the vast distance between the particles in nebulas the gravitational attraction between the nebulas are very week.
But, it is just strong enough to keep the nebulas together.

21. Pressure Pushes Matter Apart
Temperature – a measure of the average kinetic energy, or the energy in motion, of the particles in an object.
The outward pressure keeps the nebulas from collapsing by counter acting the gravitational pull inward.

22. Gravity and Pressure in a Nebula

23. Upsetting the Balance
Solar Nebula – the cloud of gas and dust that formed our solar system.
There are two ways in which you can disturb gravity and pressure:
Nearby star explodes
Two nebulas collide.

24. How the Solar System Formation Summary
Solar nebula collapsed.
The nebula became denser and denser and the attraction between the particles increased.
Due to the increase collisions the center of the cloud became very hot.
The cloud flattened out into a rotating disk in which all of the planets still follow this rotation.

26. From Planetesimals to Planets
As the dust began to circle the warm center particles began to collide to form golf ball-sized bodies.
The bodies were then pulled into the nebula where the began to collide more allowing them to grow to kilometer-wide bodies.
Planetesimals – large bodies of rock that have collided to form “small planets”

27. From Planetesimals to Planets
The majority of these Planetesimals are the cores of many planets.
Others collide with planets creating large craters.

28. Gas Giant or Rocky Planet?
Largest planetesimals formed near the outside of the rotating solar disk, where hydrogen and helium were located.
Formed far enough away that their gravity was able to attract the nebula gas.
Smaller planets formed closer to the rotating solar disk.
Temperatures were to hot for the gases to remain so they became mostly rock like planets.

29. The Birth of a Star
At the same time the planets were forming material kept pulling in toward the center of the nebula.
Eventually temperature got so hot that fusion reaction began to occur between hydrogen atoms creating helium.
Fusion reactions released large amounts of pressure balancing the inward pull of gravity.

30. The Birth of a Star
As the gases became balanced, stabilization occurred, giving birth to a new star.
The Sun

31. The solar systems motion in the galaxy.
Explain

32. Galaxy’s motion in the universe.
Explain

33. Astronomy: The Original Science
Studying the movement of objects in the sky was so important to ancient people that they built observatories.
This lead to science known as astronomy.

34. A Revolution in Astronomy
Rotation – the spin of a body on its axis.
Half of the Earth is always facing the sun = Daylight
Half of the Earth is facing away from the sun = night

35. A Revolution in Astronomy
Orbit – the path that a body follows as it travels around another body in space.

36. Our Modern Calendar
The years, months, and days of our modern calendar are based on the observation of bodies in our solar system.
Year – the time required for the Earth to orbit once around the sun. (365 days 6 hours)
Month – roughly the amount of time required for the moon to orbit once around the Earth.
Month is derived from the word moon. (29.5 days)

37. Rotation of Planets
Prograde Rotation – the counterclockwise spin of a planet or moon as seen from above the planet’s North pole.
Sun will rise in the east and set in the west like on Earth.

38. Rotation of Planets
Retrograde Rotation – the clockwise spin of a planet or moon as seen from above the planet’s North Pole.
Sun rises in the west sets in the East.

39. Our Modern Calendar
Day is the time required for the Earth to rotate on its axis. (23hr56min)
Length of day animation

40. Seasons Why do seasons occur?
Earth is tilted at an angle of 23.3 degrees
Earth rotates around the sun.

41. Computer Lab Activity: Seasons

42. Precession
Precession – Change in direction of the axis without any change in tilt.
Different stars will be seen at the poles and near the equator regions.
Seasons do not change as long as the angle of 23.5 degrees remains the same.

43. Nutation Nutation – Wobbling around the “precessional axis”.
Due to the pull of the Moon on Earth.
Occurs every 18 years.
Cause minor increase or decrease in the amount of seasonal effects.

44. Barycenter
Barycenter – is the point between two objects where they balance each other.
This is the point on a line where the two planets orbit each other.

45. Barycenter
When a moon orbits a planet, or a planet orbits a star, both bodies are actually orbiting around a point that lies outside the center of the primary (the large body).
For example: The moon does not orbit the exact center of the Earth, but a point on a line between the Earth and the Moon approximately 1,710 km below the surface of the Earth.
This is also the point in which the moon and the Earth orbit the Sun as a system.

46. Barycenter The Sun is not stationary in our solar system either.
It actually moves as the planets tug on it, causing it to orbit the solar system’s barycenter.
The Sun never strays too far from the solar system barycenter.

47. Star Observations
Circumpolar Star – A star directly above an observer.

48. A Revolution in Astronomy
Revolution – one complete trip along an orbit.
Period of Revolution – the amount of time a planet takes to complete a single trip around the sun.
Earth takes days to orbit the sun
Mercury takes 88 days to orbit the sun.

49. Alien Planets Activity

50. Kepler’s First Law of Motion
The path of the planets about the sun is elliptical in shape, with the center of the sun being located at one focus. (The Law of Ellipses)
“Planets move in elliptical orbits.”

52. Kepler’s Second Law of Motion

53. Kepler’s Third Law of Motion
Planets that are more distant from the sun, such as Saturn, take longer to orbit the sun.

54. Kepler’s Third Law of Motion
Planet
Period
(yr)
Ave.
Dist. (au)
T2/R3
(yr2/au3)
Mercury
0.241
0.39
0.98
Venus
.615
0.72
1.01
Earth
1.00
Mars
1.88
1.52
Jupiter
11.8
5.20
0.99
Saturn
29.5
9.54
Uranus
84.0
19.18
Neptune
165
30.06
Pluto
248
39.44

55. Newton to the Rescue
Kepler was never able to explain what caused planets closer to the sun to move faster than planets farther away.
Newton explained this process by the force of gravity.

56. The Law of Universal Gravitation
Newton’s law of universal gravitation states - that the force of gravity depends on the product of the masses of the objects divided by the square of the distance between the objects.

57. The Law of Universal Gravitation

58. Orbits Falling Down and Around
Inertia – an objects resistance to change speed and direction.
This is why the moon does not crash into the Earth.
The moon always continues to move forward but is reacted upon by the gravity of the Earth.

59. Orbits Falling Down and Around
Think of a ball twirling on a string.
As long as you hold on to the string the ball will never fly off and will continue to go around in a circle.
As soon as the ball is released it will fly off in a straight direction.
The same thing happens to all the planets and moons in the solar system.

60. The Law of Universal Gravitation