1. Astronomy
Created By:
Mr. Kreeger

2. Table of Contents Earth in the universe Galaxies Doppler Effect
Hubbles Law
Stellar Evolution
HR Diagram
Celestial Sphere
Altitude-Azimuth System
Constellations
Space Objects
Sun
Models of Celestial Motion
Solar System
Orbital Forces

3. Table of Contents Earth in the Universe Galaxies Sun Solar System
Space Objects

4. Earth in the Universe
When looking at stars we are seeing where star use to be (looking back in time)
Universe so large we use speed of light to measure distance (300,000km/s, 186,000miles/s)
Light year- Distance light travels in one year (9.5 trillion km, 6 trillion miles-A.U)
Sun-nearest star-93,000,000 miles away (8 min)
Proxima Centauri- 4.3 light years
Polaris-300 light years

5. Galaxies A system of billions of stars
Spiral-Shaped like a pinwheel with huge spiral arms. (Milky way and Andromeda)
Elliptical- Look like blobs, can be circular or flattened. (Most common)
Irregular- No definite shape

6. Picture of Milky Way

7. Doppler Effect
Provides evidence that galaxies are rushing away from us.
Spectral lines shifted to red- Moving away
Spectral lines shifted to blue- Moving toward

8. Hubble’s Law
Further galaxies are moving at a faster rate than closer ones (Degree of red shift)
Bread expanding is a good example- Particles in bread are moving away from each other at a speed that increases with an increase in distance

9. Poll: In which list are celestial features ...
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Poll: In which list are celestial features ...

10. Poll: The unit most used by astronomers to ...
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Poll: The unit most used by astronomers to ...

11. Poll: The Milky Way galaxy is best describe...
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Poll: The Milky Way galaxy is best describe...

12. Stellar evolution
Nebula (gas and dust) condensed by gravity and nuclear fusion takes place.
First star produced is red giant

13. Stellar Evolution Red Giant changes to White dwarf
White Dwarf to Neutron Star
Neutron star to Supernova
Supernova to Pulsar
Pulsar to blackhole

14. Hertzsprung Russell Diagram

15. Celestial Sphere
This is an imaginary sphere that encompasses all objects in the sky.
Horizon- The line at the edges of the earth where the celestial sphere meets the earth
Zenith- The point directly above the observers head. At NP this is Polaris

16. Altitude-Azimuth system
Can be used to describe positions of celestial objects
Altitude- Distance, in degrees, above horizon
Azimuth- Distance, in degrees, measured clockwise from the due north position (Due north= 0 degrees)
Ex: A star is halfway between the horizon and zenith and is due south. Alt=45 degrees and azimuth = 180 degrees

17. Star Trails From NP Perspective

18. Constellations
Stars grouped in patterns that outline people and animals (88, 70 visible in NYS)
Circumpolar- Visible every night

19. Poll: What are the two most abundant elemen...
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Poll: What are the two most abundant elemen...

20. Poll: Compared to the sun, Polaris is
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Poll: Compared to the sun, Polaris is

21. Poll: Which star is cooler and many times b...
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Poll: Which star is cooler and many times b...

22. Poll: Compared to the surface temperature a...
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Poll: Compared to the surface temperature a...

23. Poll: Compared to other groups of stars, th...
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24. Space Objects
Asteroids-Small rocks, orbit the sun between Mars and Jupiter (Asteroid Belt)
Ceres- 1000km in diameter
Hermes came close to earth (800000km from earth)

25. Space Objects
Comets-Chunks of ice, have elongated orbits near the sun, when passing the sun radiation vaporizes ice causing flowing tail.
Halley’s Comet- Takes 76 years to make 1 orbit

26. Space Objects
Meteoroids- Fragments of rocks or ice traveling in space.
Meteors- (Shooting Stars)-Streaks of light caused by meteoroids passing through earth’s atmosphere.
Meteorite- If object reaches ground.
Perseids-August 10-14
Orionids-October 18-23
Taurids- November 1-15
Geminids- December 10-16

27. Sun Sun-Made of all gas Core-makes up 10% (15,000,000C)
Radiative Zone- Energy moves from atom to atom as EM waves (2,500,000C)
Convective Zone- Transfer energy by moving gases and liquids (1,000,000C)
Photosphere-Has a grainy appearance b/c gases are rising and sinking in convection zone. (surface)
Chromosphere-Above photosphere ( C)
Corona-Layer of gas heated by suns magnetic field

28. Sunspots
Sunspot cycle lasts about 11 years-Glaciers appeared during cooler times “little ice age”
Sunspot cycle shows that sun rotates

29. Models of Celestial Motion
Geocentric-Earth is the center of the universe.
Heliocentric-Sun is the center of the universe.

30. Solar System
Formation-Formed about 5 million years ago. Planets accumulated from material in solar nebula during the birth of the sun.
Types of Planets- Affected by each planet’s location in relationship to the sun.
Terrestrial-Most similar to earth-small, low mass and high density (Mercury, Mars, Earth, and Venus)
Jovian- Most similar to Jupiter-large, high mass and low density (Saturn, Uranus, Neptune)

31. Solar System Data

32. Poll: A belt of asteroids is located an ave...
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33. Poll: In geocentric model (the Earth at the...
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34. Poll: What is the approximate average densi...
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35. Poll: Three planets known as gas giants bec...
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36. Poll: Compared to Jupiter and Saturn, Venus...
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37. Poll: Compared to the distances between the...
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38. Eccentricity = Distance between foci
Orbital Forces
Kepler’s Laws of Planetary motion
The orbits of planets around the sun are ellipses, with the sun at one of the foci.
Eccentricity is the out of roundness of an ellipse.
Closer to 0 more round closer to 1 more elliptical
Eccentricity = Distance between foci
Length of major axis

39. Orbital Forces
An imaginary line joining a planet to the sun will sweep over equal areas in equal periods of time
Perihelion (Planet closest to sun)- fastest speed
Aphelion (Planet furthest from sun)- slowest speed

40. Orbital Forces
3. The square of any planet’s orbital period (T^2) is proportional to the mean radius of it’s orbit cubed (R^3) (T^2~R^3)