1. The Sun-Earth-Moon System
Earth Science
Chapter 27
Sections 1, 2, 3

2. Tools of Astronomy
Chapter 27
Section 1

3. Radiation Electromagnetic Radiation: Electromagnetic Spectrum:
Consists of electric and magnetic disturbances traveling through space as waves.
Electromagnetic Spectrum:
The wavelength and frequency of electromagnetic radiation.

4. Wavelength and Frequency
Electromagnetic Radiation is classified by wavelength.
Distance from crest to crest.
It is also classified by frequency.
The number of waves or oscillations that pass through a point in one second.
See p. 764

5. Electromagnetic Radiation

6. Wavelength and Frequency
Hz – Hertz
A unit equal to 1 cycle per second
Scientists choose their tools based on the type of radiation they want to study in space.
p. 765

7. Telescopes
Give us the ability to observe electromagnetic wavelengths beyond what a human can detect
Aperture: the diameter of an opening where light is let in
Human eye- 7 mm
Telescope- 10 m
Benefits:
Larger aperture than eye
Can collect object too dim for the eye to detect
Eye only views objects for 1/10 of a second. Lenses can stay open for hours to collect more light
Tools used with satellites
Photometer
Intensity of visible light
Spectrophotometer
Different wavelengths of radiation

8. Refracting and Reflecting Telescopes
Refracting Telescope
Reflecting Telescope
Use lenses to bring light into focus
First telescopes
Use mirrors to bring light into focus
Used by most astronomers because mirrors can be made larger than lenses

9. Telescopes using Non-visible Wavelengths
Infrared and ultraviolet radiation can be focused with mirrors- reflecting telescope
X-Rays can’t be focused by normal mirrors
Gamma rays can’t be focused at all

10. Telescopes Using Non-visible Wavelengths
Radio telescope:
Collects longer wavelengths
Uses a large dish antenna
Reflects waves to a single point
A receiver collects the signal and converts it to electric signals

11. Telescopes Using Non-visible Wavelengths
Interferometry
Uses images from several telescopes to produce a single image
Scientists get a detailed image with the same resolution as one large telescope with a dish as large as the distance between the telescopes

12. Space Based Astronomy
Instruments in space collect data with our Earth’s atmosphere blurring the images.

13. Hubble Space Telescope
Orbits Earth every 97 minutes
Obtains sharp visible light images
James Webb Space Telescope (planned for 2013)
Observe the infrared range

14. Spacecraft Sent directly to the bodies to collect data Robotic probes:
Spacecraft that can make close up observations or collect information
Cassini spacecraft
Observed Saturn’s rings and moons
Mars Reconnaissance Orbiter
Used high resolution cameras to search for signs of life
New Horizons
Launched toward Pluto and beyond with visible, infrared and ultraviolet light cameras

15. Spacecraft
Cassini
Mars Reconnaissance Orbiter
New Horizons

16. Human Spaceflight
In order to pursue more advanced human spaceflight, scientists need to study:
The effects of weightlessness on humans, plants, and other phenomenon.
The effects of radiation
The Space Shuttle program allows scientists to study short term effects

17. Human Spaceflight
Longer term effects need to be studied on space stations
International Space Station
A multicountry space station

18. The Moon
Chapter 27
Section 2

19. Exploring the Moon First explored with telescopes
Most information was gained by probes and sending men to the moon
Lunar Prospector
Clementine

20. Exploring the Moon 1957 Soviet Sputnik 1961 Yuri A. Gagarin
First satellite
1961 Yuri A. Gagarin
First human in space
1961 Alan B. Shepard, Jr.
First American in space during Project Mercury
Project Gemini
First two person crew in space
1969 Apollo I1
Neil Armstrong first human on the moon.

21. Lunar Surface Lunar surface is dark
Albedo: the percentage of incoming sunlight that its surface reflects
About 7%
Earth’s Albedo is around 31%
Moon has no atmosphere to absorb heat so its surface is hot (Varying temperatures
Light side: 127˚ C
Dark side: -173 ˚ C

22. Lunar Surface Lunar Highlands Maria
Heavily cratered regions of the moon
Light colored
Maria
Dark smooth plains with few craters

23. Lunar Craters Impact craters Ejecta Rays Rilles
Objects have crashed into the moon
Ejecta
The material blasted out of the craters
Rays
Trails of ejecta that radiate from the crater
Rilles
Meandering valley- like structures
Might be collapsed lava tubes

24. Lunar Properties One of the largest moons Solid rocky body
Composed of mostly silicates
Similar to Earth
Highlands
Rocks formed by the fusion of smaller pieces of rock during impacts
Maria
Predominately basalt (volcanic) but with no water

25. History of the Moon Radiometric dating
bya
Heavily bombarded during the first 800 million years
Breaking and heating of surface formed a layer of ground up rock
Regolith- the fine layer of ground up rock
Depth varies with location

26. Layered Structure Crust Upper Mantle- solid Lower Mantle- molten
Varies in thickness
Thickest on the far side that faces away from Earth
Upper Mantle- solid
Lower Mantle- molten
Core- solid iron

27. Formation of Maria During bombardment Lava filled the impact basins
Left dark smooth plains
Fewer maria on the far side because the crust is thicker and the lava was too far under the surface

28. Tectonics Moon experiences about one moonquake per year
Strong enough to shake plates from a cupboard
Not much seismic activity

29. Formation

30. Impact theory- widely accepted
Several theories
Impact theory- widely accepted
Collision with a Mars shaped object and Earth 4.5 bya
Parts of the fractured Earth flew into space
Over time the orbiting objects came together to form the moon.
This explains the similarities to the composition of the moon and the Earth

31. The Sun-Earth-Moon System
Chapter 27
Section 3

32. Daily Motions Daily rotation Day Length Causes the Coriolis effect
1 solar day is on revolution on Earth’s axis
24 hours

33. Annual Motions
Earth revolves around the sun in a elliptical plane

34. Earth’s Tilt
Earth’s tilt is approximately 23.5˚ relative to the ecliptic
Earth’s axis remains fixed in space
When Northern hemisphere is toward the sun the Southern hemisphere is away from the sun

35. Solstices
A solstice occurs when the sun is at its farthest distance from the equator
Summer solstice brings the longest day of the year and winter solstice brings the shortest

36. Solstices Summer solstice in North America-
Note the rays are strongest in the Northern portion of the globe
Rays are weakest in the southern portion. This is their winter solstice.

37. Equinoxes Earth’s axis is perpendicular to the sun.
Days and nights are equal length
Occur in spring and fall

38. Phases of the Moon Waxing Waning
The increasing visible light starting with the new moon
Waxing crescent, first quarter and waxing gibbous
Waning
The decreasing visible light starting at the full moon
Waning gibbous, third quarter, waning crescent

39. Synchronous Rotation
When the moon orbits Earth the same side faces it.
The moon rotates exactly one time as it goes around the Earth
This is synchronous rotation