1. Topic F Notes
Use Cornell note format

2. Johannes Kepler 17th Century mathematician, astronomer and astrologer
Best known for his three laws of planetary motion
Explains the movement of the planets as part of his theory of the universe

3. Nicholas Copernicus Renaissance mathematician and astronomer
Was the first person to suggest that the Earth was not the center of the universe
Formed the heliocentric model of the universe which placed the Sun, rather than the Earth, at the center

4. Theory that suggests the Universe was created when a point of unimaginably intense energy violently expanded creating time and space and everything in it.
Evidence that supports the big bang theory includes: 1)background radiation has been found throughout the universe, 2)the red shift and 3)scientists have not found a star older than the approximate age of the Universe
Scientists predict the Universe will expand forever
Big Bang Theory

5. Background Radiation Afterglow of the big bang
Can be seen at different wavelengths of the electromagnetic spectrum

6. The Red Shift and Blue Shift
A red shift is seen when light coming from an object is moving away from another object
A blue shift is seen when the light coming from an object is moving towards another object.
Most celestial bodies in the universe show a red shift suggesting all objects are moving away from each other à supports the big bang theory that the universe is expanding and will expand forever
The FREQUENCY of light is what allows it to have a red or blue shift
Distant galaxies are moving away from Earth faster than galaxies that are nearby

7. Speed of Light All light travels at around 300,000 km/sec
The speed of light is 299, 792,458 METERS PER SECOND
This means that light could travel from San Francisco to New York 62 times in ONE SECOND
All light travels at around
300,000 km/sec

8. Light Year (ly) The distance light travels in one year
The next closest star to our Sun is 4.3 ly away and is named Proxima Centuri
What are the limitiations (problems) with this model of the Earth, Sun, and 3 other stars?

9. Sirius
Gliese 876
Gliese 436

10. Apparent Magnitude
A measure of how bright a star is when seen from Earth
Stars may appear bright because they either produce a lot of light OR they are very close to Earth. There is no way to tell if the star is bright because it is close or because it is actually a bright star without more data.
Apparent Magnitude= How bright does the star APPEAR???

11. Absolute Magnitude
A measurement of the amount of light the star give off (Luminosity, Brightness)
This is more accurate than apparent magnitude.
Our Star (the Sun) is average in size, average in magnitude and is considered “middle age” star or about 5 billion years old in a 10 billion year lifespan and is considered a Main Sequence Star

12. If light travels 299,792,458 m/s, how long does it take light to travel one meter?

13. The Electromagnetic Spectrum

14. Spectral Lines
A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorpion of light in a narrow frequency range. Spectral lines are often used to identify elements and used to identify the elemental components of stars and planets which would otherwise be impossible.

17. Hertzsprung-Russell Diagram (HR Diagram)
Note: Hot main sequence stars are brighter than supergiants, but they are bigger than most main sequence stars, as well.

19. How to read an HR Diagram
A scatter plot of star temperature (x-axis) and luminosity (y-axis)
Temperature of star is measure in Kelvins
Luminosity is measure in Solar Units
Use it for categorizing star age
Important Difference than regular scatter plots and HR Diagrams: Read the X-Axis from Right to Left

20. Star Life Cycle
Nebula (giant cloud of gas and dust)  Protostar (baby star, hydrogen fusion begins)  Main Sequence Star (where stars spend most of their life) Red Giant Depending on mass it will either become a White Dwarf (low mass) or Neutron star (large mass)/Black Hole (very large mass)

21. Galaxy Shapes Spiral Elliptical Irregular
The Milky Way is a spiral galaxy and Earth is located in one of the spiral arms near the edge of the galaxy

22. Barred Spirals