1. Stars and Galaxies

2. Constellations
Constellations- Certain groups of stars named after animals, characters in mythology, or familiar objects
From earth constellations look like groups of stars close together
Brightest star in the winter sky is Sirius
88 constellations
Star Polaris – North Star

5. Appear to move because earth is moving
Stars also appear to change position in the sky throughout the year
Earth revolves around the sun
As earth orbits different constellations come into view while other disappear
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7. Absolute and Apparent Magnitudes
Absolute Magnitude
Is a measure of the amount of light is actually given off
Apparent Magnitude
Amount of light received on earth
Example: Sirius – 100x closer to earth then Rigel, therefore appears brighter

8. Determining distances
Parallax
Apparent shift in the position of an object when viewed from two different positions
The nearer an object is to the observer, the greater its parallax
Distance in space are measures in light years
Light year is the distance light travels in 1 year
Light travels at 300,000 km/s

11. Nearest star other then the sun is Proxima Centuri
4.2 light years away
It takes 4.2 years for light from that star to reach you
Stars temperature is determined by the color of the star

15. Very hot stars – blue white color
Cool stars – orange or red
Stars temperature close to the sun – yellow

17. Evolution of Stars H-R Diagram
Graph that shows relationship a stars temperature to its absolute magnitude
Most stars fit into the main sequence of stars
Hot blue bright stars (upper left)
Cool Red dim stars (lower right)
Sun is a yellow medium temp. star
90% of all stars are Main Sequence

20. The other 10% are Super Giants, Giants, White Dwarfs
Evolution of Stars
Stars begin as a large cloud of gas and dust called a nebula
At high temperature Fusion begins
Main sequence star forms
Begins to use its hydrogen

21. When hydrogen fuel runs out, expands and becomes a giant
Core collapses
Outer portion of the giant blows away forming a white dwarf
Eventually the white dwarf uses its fuel and becomes a cold dead star
If a super giant (30 times our sun) collapses it may turn into a black hole

25. Black Hole

30. The Sun

31. The Sun 99% of all matter in our solar system is the sun
It is the center
Makes life possible on earth
Just an average star
Enormous ball of gas, fusing hydrogen into helium at its core

33. Layers of the suns atmosphere
Photosphere –
lowest layer from which light is given off
Temp. 6000* C
Chromosphere-
Upward about 6000 Km
Corona
Largest layer, extend out millions of km in space
Temp. 2, 000,000*C
Charge particle escape causing solar wind

34. Sunspots
Dark areas on the suns surface, which are cooler then their surroundings
Sun rotates
Rotates faster at its equator than at its poles
It takes 25 days for a sunspot to go around the sun at the equator

37. Prominences and flares
Intense magnetic field associated with sunspots may cause prominence, huge arching columns of gases
So eruptive that material from the sun is blasted into space 1000 Km/sec

41. Sun is a main sequence star
Most star are in a system in which two stars orbit each other (Binary system)
Our sun does not do this
Some stars move through space as star cluster

43. Galaxies

44. Galaxies Large group of stars, gas, and dust held together by gravity
Galaxies are separated by huge distances, often millions of light years
Three types of galaxies
Elliptical
Spiral
Irregular

45. Types of Galaxies

47. Elliptical is the most common
Vary in size
Football shaped
Cluster of galaxies that the Milky Galaxy belongs to is called Local Groups
Spiral Galaxies have spiral arms
Milky Way is a spiral Galaxy

48. Irregular Galaxies
Many different shapes
Cloud of Magellan Orbit

49. Spiral

50. Irregular

51. Elliptical

52. Milky Way Galaxy In our galaxy, all stars orbit a central region
200 million years for the sun to orbit this central region
Contains more then 200 billion stars

55. Expansion of the Universe
When a Spectrograph is used to study light from galaxies beyond the Local group, there is a red shift in the light
Because there is a red shift in the light, all galaxies must be moving away from earth
Doppler Shift
Big Bang Theory states that between 15 and 20 billion years ago, the universe began expanding out of an enormous explosion

59. There is evidence that supports the Big Bang Theory
Scientist have discovered radiation in space that they believe was created by the explosion
All matter exerts a gravitational force
If there is enough matter, gravity will halt expansion
A big crunch would result

60. Meteors
A meteoroid is matter revolving around the sun or any object in interplanetary space that is too small to be called an asteroid or a comet
A meteorite is a meteoroid that reaches the surface of the Earth without being completely vaporized
term meteor describe the streak of light produced as matter in the solar system falls into Earth's atmosphere creating temporary incandescence resulting from atmospheric friction.