1. Constellations & Stars

2. I. Constellations
Group of stars that appear to form a pattern in the sky.
88 recognized by International Astronomy Union

3. A. Zodiac
Band of 12 constellations along the ecliptic.

4. B. Ecliptic
– the plane of the Earth’s orbit around the sun
The apparent path that the sun (and planets) appear to move along against the star background.

5. Ecliptic

6. C. Circumpolar Constellations
Can be seen all year long
Never fully set below the horizon
Appear to move counter clockwise around Polaris
Caused by Earth’s Rotation

7. Circumpolar Constellations

8. Star Trails

9. Examples of Circumpolar Constellations
Ursa Major – The Big Bear
Ursa Minor – The Little Bear
Cassiopeia – Queen on Her Throne
Draco- The Dragon
Cepheus- The King

10. # of stars seen as circumpolar depends on the observers latitude
Further North the observer lives, the more stars will appear circumpolar
Earth turns west to east
Sky appears to turn east to west

11. D. Ursa Major Best known constellation Common name is Big Dipper
Pointer stars- front 2 stars of the Big Dipper which point to Polaris (North Star)

12. II. Seasonal Changes in Constellations
Big Dipper
In Fall: Low over northern horizon
Spring: High overhead
Cassiopeia
In Fall: Straight overhead
Spring: Low over northern horizon

13. Seasonal Change & Nightly change of the Dippers

14. III. Summer Constellations
1st 3 bright stars that rise form the Summer Triangle
Vega- in Lyra the Harp
Altair- in Aquilla the Eagle
Deneb – in Cygnus the Swan (Northern Cross)

15. Summer Triangle

16. IV. Most Famous Winter Contellation
Orion Contains:
Betelgeuse (Bet el jooz) a bright red super giant star found forming Orion’s right shoulder
Rigel – a blue super giant: 7th brightest star in the nighttime sky

18. 3 Stars of Orion’s Belt
Can be used to find 2 other constellations & a star cluster
Canis Major- (Big Dog) follow the line made by the 3 stars of Orion’s belt down to the left
Sirius- the brightest star in the nighttime sky is found in Canis Major

19. 2. Taurus (the Bull)
Follow the line made by Orion’s belt up & to the right
Aldebaran- Red star that is the eye of the bull is the 13th brightest in the nighttime sky

20. 3. Pleiades Star Cluster (7 sisters)
Follow the line made by Orion’s belt up to the right, go through Taurus to a clump of stars to the right.
Called Subaru in Japan – means “Unite”

21. V. Kinds of Stars
Red Giant - large red star at least 10x diameter of the sun
Old Stars
Ex. Aldebaran
The sun will swell into a Red Giant when it is old

22. B. Super Giant Largest of all stars 100x more luminous
Explode as a Super Nova
Can form Black Holes
Ex. Betelgeuse, Rigel, Polaris

23. C. Dwarf Stars Less luminous Very dense, mostly carbon
Tightly packed nuclei
Remains of a red giant that ran out of fuel
1 cup full of star =20 tons or 5 elephants. 
Most are red/orange/yellow
White dwarf is the exception to the color
Sun is a yellow dwarf

26. Size Comparison of Various Stars

27. VI. Variable Stars Change in brightness over regular periods of time
Ex. Cepheid Variables/Pulsating Stars Binary Stars & Eclipsing Binary Stars

28. A. Cepheid Variables/ Pulsating Stars
Change in brightness as they expand & contract
Unequal balance between gravity & nuclear fusion
Ex. Polaris, Betelgeuse

29. B. Binary Star Systems
Two stars of unequal brightness revolving around a center point
Ex. Algol & its companion star in Perseus

30. C. Eclipsing Binary Stars
Two close stars that appear to be a single star varying in brightness.
The variation in brightness is due to one star moving in front of or behind the other star.
Occurs because we see the system on edge instead of from above or below

31. VII. Pulsars or Neutron stars
Discovered in 1967 (LGM)
A distant heavenly object that emits rapid pulses of light & radio waves
Formed when a Super Giant collapses; Protons & Electrons are forced so close together that they fuse and form only neutrons 

32. Twinkle Twinkle Little Star
"Twinkling Stars" are due to Earth's atmosphere

33. VIII. Life Cycle of a Medium Mass Star
Nebula
Protostar
New/Stable State Star
Red Giant
Planetary Nebula
White Dwarf
Black Dwarf

34. 1. Nebulae (Plural of Nebula)
Space gas seen as faint glowing clouds
Mostly hydrogen   
Star dust is extremely small, smaller than a particle of smoke & widely separated, with more than 300 ft. between individual particles.
Nebulae still hinder star gazing because they absorb light which passes through them.

35. Ex. Nebula found in Sagittarius
Types of Nebulae
Diffuse Nebula - gases glow from stars w/in them
Ex. Nebula found in Sagittarius

36. Types of Nebulae Dark Nebula - nebula not near a bright star
Ex. Horse Head Nebula in Orion

37. 2. Protostar
Shrinking gas balls, caused by a swirl of gas forming dense areas. 
The gravity of the dense swirl in turn attracts nearby gases so a ball forms.
Nuclear fusion occurs & Helium is formed from Hydrogen
A new star is born in our galaxy every 18 days

38. 3. Stable State Star
Star that releases energy in enough force to counter balance gravity
Star stops contracting
Also known as a main sequence star
Ex. Sun

39. 4. Planetary Nebula
The outer layers of the Red Giant puff out more and more.
The star loses gravitational hold on its outer layers and they get pushed away by the pressure exerted from solar winds

40. Planetary Nebula

41. 5. White Dwarf Fuel is used up No nuclear fusion occurring
Remaining heat radiates into space

43. IX. Life Cycle of a Massive Star
1st three steps are similar
Super Giant
Super Nova
Neutron Star / Pulsar
Black Hole

44. 1. Super Giant Rare stars, largest of all 100x more luminous
Only stars with a lot of mass can become super giants
Some are almost as large as our entire solar system
Ex. Betelgeuse & Rigel

45. 2. Super Nova Explosion from a massive Super Giant
Outer layer blasts away at end of Life Cycle
Emits light, heat, X-rays, & neutrinos
Leaves behind a neutron star or black hole

46. 3. Neutron Star/ Pulsar The remains of a super nova
Very small, super-dense star which is composed mostly of tightly-packed neutrons
Rapidly spinning leftovers of a star
Emits energy in pulses

47. 4. Black Hole
Occurs when a star's remaining mass is greater than three times the mass of the Sun
Star contracts tremendously
Incredibly dense with a gravitational field so strong that even light cannot escape.

48. Life Cycle of a Massive Star

49. X. Distance to stars
The Sun is closest star to Earth
Takes light 8 minutes to reach Earth
Avg. distance:150,000,000Km = 1 AU distance from Earth to the Sun
Next nearest star is Proxima Centauri 4.2 light years away; it can only be seen in the southern hemisphere     

50. E. Light year
The distance light has traveled in a year
9.5 x 1012 Km/yr
Speed of light 300,000 Km /sec

51. XI. Physical Properties of Stars
Nuclear fusion supplies the energy for stars
Huge size & mass of a star means outer layers press inward w/ tremendous pressure
Hydrogen ignites
Star becomes a huge nuclear bomb
Hydrogen nuclei combine to form Helium

52. B. Color of star depends on surface temp.
Blue - hottest stars Ex. Rigel in Orion; Vega in Lyra; Sirius in Canis Major
Yellow - medium stars ex. Sun
Red - coolest stars Ex. Betelgeuse in Orion, Antares the heart of Scorpio, Aldebaran in Taurus

53. C. Star size -Varies, large range Smallest can be smaller than Earth
Largest may be 600,000,000 x Earth.

54. D. The Sun
is an average star
yellow in color
300,000 x the mass of Earth

55. XII. Luminosity Brightness of a star Depends on size & temperature
Hertzsprung-Russell Diagram graphs Absolute Magnitude (or Luminosity) vs. Temperature of stars
Shows the life cycle of stars

56. Hertzsprung-Russell Diagram

57. A. Absolute Magnitude
Measure of the amount of light it actually gives off if all stars were placed a distance of 32.6 light years away
Lower # means brighter star
Negative #’s are the brightest
Ex. Sun = Sirius = 1.4 Rigel = –7.0
Rigel’s the Brightest of the 3 listed if all were lined up next to each other.

58. B. Apparent Magnitude
A measure of the amount of light received on Earth
Stars below 0 are brightest
Each magnitude differs by 2.5
1st magnitude is 100 x brighter than 6th magnitude
Ex. Sun = – 26.8 Sirius = – Full Moon – Rigel = .11
Sun is the brightest in our sky.

59. XIII. Galaxies
Systems containing millions or billions of stars, gas, & dust held together by gravity       Ex. Milky Way
There are great distances between galaxies
The Milky Way belongs to a group or cluster of galaxies called the local group

60. Spiral Galaxy Like the Milky Way

61. Three major classes of galaxies:
Elliptical - shaped like large ovals or football shape
Spiral - pinwheel shaped; our sun is on a spiral arm of the Milky Way
Irregular - many different shapes that aren't like the other two

62. XIV. Quasar Quasi stellar radio source
Galaxies, very far away, with bright centers
Thought to have a super massive black hole at center
Most luminous objects known to man

63. XV. Electromagnetic Spectrum
The arrangement of electromagnetic radiation from Radio waves to Gamma waves

64. Stars Emit: Visible light X-rays Radio waves Infrared waves
Ultraviolet waves

65. Venus & Saturn by E-spectrum
Ultra violet Visible Infrared Radio
Ultra violet Visible Infrared Radio

66. X-ray & Ultra Violet Image of Sun

67. Visible, Infrared & Radio Images of Sun

68. A. Electromagnetic waves:
Differ in wavelength & frequency  
All electromagnetic waves travel at the speed of light; 300,000 km/sec

69. Parts of a Wave

70. a has a longer wavelength (distance from one crest to another) but lower frequency ( # of waves that pass by a point in a second)

71. b has a shorter wavelength but a higher frequency

72. B. Spectroscope Instrument that separates light into its colors.
Contains:
ü Prism at one end
ü Slit at opposite end which lines up with the light source

73. C. 3 Types of Spectra Continuous Spectrum Brightline Spectrum
Darkline Spectrum

74. How Spectra are Produced

75. 1. Continuous Spectrum Produced by a glowing solid
Example a Tungsten white light bulb, & white sunlight.

76. Continuous Spectrum Cont’
Continuous set of emission lines forming an unbroken band of colors from red to violet.
Shows the source is sending out light of all visible wavelengths.   

77. All the colors of the rainbow
Visible Spectrum
red  orange yellow green blue indigo       violet
ROY G BIV
All the colors of the rainbow
A continuous spectrum

78. 2. Dark-Line Spectrum / Absorption Spectrum
Produced when a cooler gas lies between the observer and an object emitting a continuous spectrum
Example: 1. The atmosphere of planets
2.Outer layers of a star

79. Absorption Spectrum Cont’
The cooler gas absorbs specific wavelengths of radiation passing through it.
This spectrum appears as a continuous spectrum of all colors with a number of gaps or dark lines throughout it.

80. 3. Bright-Line Spectrum / Emission Spectrum
Produced by a glowing gas which radiates energy at specific wavelengths characteristic of the element or elements composing the gas
Example Neon signs, black lights, LED’s

81. Emission Spectrum Cont’
This spectrum consists of a number of bright lines against a dark background.
Each elements has its own distinctive spectra much like a fingerprint

82. XVI. The Doppler Effect
as sound approaches the wavelength is compressed so the pitch is higher
as sound leaves the wavelength is stretched out so the pitch is lower
The same thing happens with light 

83. Doppler Effect

84. Red Shift
If a star is moving away from Earth there is a red shift, of its line spectra; if the star is moving toward the Earth there is a blue shift of its line spectra  

85. Red Shift
Red shift is evidence the universe is expanding.