1. Stars

2. Distances To The Stars Stars are separated by vast distances.
Astronomers use units called light years to measure the distance of stars
A light-year is the distance that light travels in a vacuum in a year or approximately 9 trillion kilometers or 6 trillion miles.
Proxima Centauri is the closest star to the sun.

3. Properties of Stars
Astronomers classify stars by their color, size, and brightness. Other properties of stars are chemical composition and mass.
Color and Temperature – a stars color indicates the temperature of its’ surface.
The hottest stars appear blue
The cooler stars appear red
The spectrum of color in a star is from blues to greens to yellows and reds.

4. Brightness
The brightness of a star as viewed from Earth is dependent on many factors such as color intensity and distance.
Apparent Brightness – is the brightness of a star as it appears from Earth.
The apparent brightness decreases as its distance from you increases
Absolute Brightness – is how bright a star really is. The absolute brightness is a characteristic of the star and is not dependent on its distance from Earth.

5. Composition Each star has its own spectrum.
Most stars have a chemical makeup that is similar to the sun, with hydrogen and helium together making up to 96 to 99.9 % of a star’s mass.

6. How Stars Form
A nebula is a large cloud of gas and dust spread out over a large volume of space.
Some nebulas are glowing clouds lit from within by bright stars.
A star is formed when a contacting cloud of gas and dust becomes so dense and hot that nuclear fusion begins.

7. The Life Cycle of Stars

8. “protostar”
The Life Cycle of Stars

9. The Life Cycle of Stars “protostar”
“Main Sequence” (longest phase in a star’s cycle
The Life Cycle of Stars

10. “protostar”
“Main Sequence”
“Red Giant”
The Life Cycle of Stars

11. The Life Cycle of Stars “protostar” “Main Sequence” “Red Giant”
“White Dwarf”

12. The Life Cycle of Stars Cycle for Massive Star: Nebula Main Sequence
Super Red Giant
Neutron Star, Pulsar, or Black Hole forms at end of its life cycle
“protostar”
“Main Sequence”
“Red Giant”
The Life Cycle of Stars
“White Dwarf”

13. Life Cycles of Stars
Adult Stars – A star’s mass determines the star’s place on the main sequence and how long it will stay.
The amount of gas and dust available when a star forms determines the mass of each young star.
The larger the star, the more energy produce.
Since blue stars burn brightly, they use up their fuel quickly and are short lived.

14. The Death of a Star
The dwindling supply of fuel in a star’s core leads to the star’s death as a white dwarf, neutron star, or black hole.

15. Groups of Stars
Astronomers have determined that more than half of all stars are members of star systems.
There are three basic kinds of star clusters: open clusters, associations, and globular clusters.
Astronomers classify galaxies into four main types: spiral, barred-spiral, elliptical, and irregular.

16. The observed red shift in the spectra of galaxies shows that the universe is expanding.
Astronomers theorize that the universe came into being in an event called the big bang.
Dark matter can only be detected by observing its gravitational effects on visible matter.
Expanding Universe

17. Star Phases: Charted on H-R Diagram

18. Explaining the H-R Diagram
“H” = Hertzsprung
“R” = Russell
graph of temperature and brightness of all stars

19. A Closer Look at the H-R Diagram

20. Star Phases: Charted on H-R Diagram
The H-R Diagram shows the relationship between absolute magnitude, luminosity, classification, and effective temperatures of stars.
The H-R Diagram can be used to define different types of stars.
It can also be used by scientists to measure how far away a star cluster is from the Earth.

21. Explaining the H-R Diagram
Temperature: horizontal (bottom) axis.
hotter at left
cooler toward right

22. Explaining the H-R Diagram
Brightness: vertical (left side) axis.
brightest stars near top
dim stars near bottom

23. Explaining the H-R Diagram
A star’s position on the diagram will change as it moves from its “birth” to its “death”.

24. Explaining the H-R Diagram
YouTube Style
Explaining the H-R Diagram

25. How do the Sun, Moon, and Earth interact to create different observable features from the Earth?

26. Seasons

27. What causes seasons? BrainPop Video
We know that the reason we have day and night is because the Earth
rotates.

28. The seasons occur because the tilt of earth’s axis causes each hemisphere to either face towards the sun, away from the sun, or both equally.
Summer
Winter
Facing away from the sun
Facing the sun
Facing away from the sun
Facing the sun

29. Notice how the Earth is always tilted in the same direction
Notice how the Earth is always tilted in the same direction. As the Earth , the part of Earth tilted toward the sun changes.
revolves

30. During what seasons is the North Pole tiled towards the sun? Why?
summer

31. During what seasons it the North Pole pointing away from the sun
During what seasons it the North Pole pointing away from the sun? Explain.
winter

32. How do tides change from high tide to low tide?
Two big bulges of water form on the Earth:
one directly under the moon
another on the exact opposite side
As the Earth spins, the bulges follow the moon.

33. Gravitational Effect of the Sun
Neap Tides
Earth, Moon, and Sun form right angles
High Tides are lower and Low Tides are higher than normal
Spring Tides
Earth, Moon, and Sun are lined up
High Tides are higher and Low Tides are lower than normal

34. Solar Eclipse
A Solar eclipse occurs when the Moon passes between the Earth & the Sun
Umbra – Area where light from the Sun is completely blocked
Penumbra – Area where light from the Sun is partially blocked
2015 © Scott Stein
My Banana is a Pink Umbrella

35. Here is an animation showing a total solar eclipse

36. Total Solar Eclipse
A total solar eclipse happens when the Moon & Sun perfectly align.
It is only visible on Earth from the Umbra
Video:
Total
Solar Eclipse
2015 © Scott Stein
My Banana is a Pink Umbrella

37. Lunar Eclipse
A Lunar eclipse occurs when the Moon passes inside of Earth’s shadow
What do you think is the difference between a Penumbral Lunar Eclipse, a Partial Lunar Eclipse, and a Total Lunar Eclipse?
2015 © Scott Stein
My Banana is a Pink Umbrella

39. This is an animation showing a total lunar eclipse from start to finish.

40. Moon’s phases

41. Crescent Moon
The Moon is crescent shaped when the lit portion of the moon looks thin and curved.
2015 © Scott Stein
My Banana is a Pink Umbrella

42. Gibbous Moon
The Moon is gibbous shaped when the lit portion of the moon is more than half full and bulges on both sides.
2015 © Scott Stein
My Banana is a Pink Umbrella

43. Quarter Moon
1/4th
1/4th
Even though the Moon looks half full, it is a quarter moon because you only see 1/4th of the actual Moon.
2015 © Scott Stein
My Banana is a Pink Umbrella

44. Quarter Moon
A 1st Quarter Moon is when the right side of the Moon is lit.
A 3rd Quarter Moon is when the left side of the Moon is lit.
2015 © Scott Stein
My Banana is a Pink Umbrella

45. Full Moon
It is a Full Moon when one whole side of the Moon is illuminated.
2015 © Scott Stein
My Banana is a Pink Umbrella

46. New Moon
It is a New Moon when the Moon does not appear illuminated by the sun.
2015 © Scott Stein
My Banana is a Pink Umbrella

47. Waning & Waxing
The Moon is Waning when the left side of the Moon is lit
The Moon is Waxing when the right side of the Moon is lit
Waxing is when the Moon appears to get bigger
Waning is when the Moon appears to get smaller
2015 © Scott Stein
My Banana is a Pink Umbrella

48. From http://starchild. gsfc. nasa
Full Moon rises as the Sun sets.
The Full Moon is in mid-sky at Midnight.
Full Moon sets as the Sun rises.
Full Moon cannot be seen during the day.

49. Also from StarChild: http://starchild. gsfc. nasa

50. The
Forces
Are
With Us

51. A force is a push or a pull that one object exerts on another object..
More than one force can act on an object at once.
The net force acting on an object is the total
of all the individual forces acting on the object.
Net force changes an object’s state of motion.
1, 2, 3

52. These forces act at a distance
The Fundamental Forces in Nature
These forces act at a distance
Gravitational Force
Electromagnetic Force
Strong Force (binds protons and neutrons in the nucleus of the atom
Weak Force - force of nature that underlies some forms of radioactivity and certain interactions between subatomic particles. 4

54. Examples of contact forces are:
Contact Forces are forces in which interacting objects are in contact with each other.
Examples of contact forces are:
Friction Force – force that acts between materials that touch as they move past each other.
Air resistance Force – Acts upon objects as they travel through the air.
Applied Force – Force that is applied to an object by another object or by a person.
5, 6

55. The friction force is the force exerted by a surface as an
F(frict)
The friction force is the force exerted by a surface as an
object moves across it, or makes an effort to move
across it.
Most of the time, the friction force opposes the motion
of an object. 7

56. The tension force is the force which is transmitted through
F(tens)
The tension force is the force which is transmitted through
a string, rope, cable or wire when it is pulled tight by forces
acting from opposite ends.
The tension force is directed along the length of the wire and
pulls equally on the objects on the opposite ends of the wire. 8

57. An applied force is a force which is applied to an object
F(app)
An applied force is a force which is applied to an object
by a person or another object. 9

58. The air resistance force is a special type of frictional force
F(air)
The air resistance force is a special type of frictional force
Which acts upon objects as they travel through the air.
The force of air resistance is often observed to oppose the
Motion of an object. It is most noticeable for objects which
Travel at high speeds or for objects with large surface areas. 10

59. The normal force is the support force exerted upon an
F(norm)
The normal force is the support force exerted upon an
Object which is in contact with another stable object. 11

60. The force of gravity acts over a distance.
Gravity Force
F(grav)
The force of gravity acts over a distance.
The force of gravity if the force with which the earth, moon
or other massively large objects attracts another object toward
itself.
By definition, this is the weight of the object. The force of
gravity on earth is always equal to the weight of the object as
found in the equation
12, 13

61. When the forces acting on an object are in opposite
Balanced Forces
When the forces acting on an object are in opposite
directions and equal in size, the forces are said to be balanced. 16

62. The table pushes upward
on the book
Gravity pulls the book
downward.
The forces acting on the book are balanced. They are equal in size but are acting in opposite directions.
The book is not moving.
Net force = 0.

63. Unbalanced forces (also called Net Forces) are unequal
forces acting on an object. During the tug-of-war competition,
one team is finally able to overcome and apply more pulling
force to the rope.  The rope starts to move in that teams favor.
Motion can only occur when an unbalanced force
(net force) acts on an object.
17,18