1. Unit C: Observing the Sky Chapter 5: The Earth-Moon System
Science 6
Unit C: Observing the Sky
Chapter 5: The Earth-Moon System

2. Lesson 1: Tools of Astronomy
Terms: Universe Telescope Refraction Reflection Wavelength Frequency Electromagnetic Spectrum

3. Lesson 1: Tools of Astronomy
What Is Astronomy?
Astronomy: the study of the universe
Universe: everything that exists—Earth and all things in space
Astronomers study different parts of the universe

4. Astronomers
As a career
For fun
Curiosity
Navigation

5. Observing the Universe
Using the eyes
Telescope: device that collects light and makes distance objects appear closer
Send robots or humans

6. Models, Theories, Hypothesis
Models, theories, hypothesis used to explain observations
Models simply world
Theory: well-tested scientific explanation
Hypothesis: scientific explanation that has not been fully tested
Theory can change when new evidence does not support the old theory’s predictions

7. What Is Light? Electromagnetic Radiation: light
Light may be invisible and includes radio waves, infrared waves, ultraviolet waves, x-rays, gamma rays
Light travels through space at: 300,000km/sec (186,000 miles/sec)
No matter travels faster
Takes 8 minutes for light to travel from the Sun to the Earth
Other stars’ light may take years to reach Earth

8. Light as a Wave
Light waves do not need a medium (something to travel through) the wave can travel through empty space
Opaque: light does not travel through
Translucent: light travels through; object unclear
Transparent: light travels through; object clear
Refraction: “bending” of light Ex. Light thru prism
Reflection: “bouncing off” of light Ex. Mirror

9. Light travels in waves
Wavelength: Distance from one peak to the next
Frequency: Number of waves that pass by a point in an amount of time—measured in hertz
Longer the wavelength-- lower the frequency

10. The Electromagnetic Spectrum
Electromagnetic spectrum: diagram that shows waves of light in order of wavelength and frequency
Different wavelengths have special names and properties
Radio, Infrared, Visible, UV, x-ray, gamma rays

11. Electromagnetic Spectrum

12. How do telescopes work? Reflecting telescope uses mirror and lens to
magnify objects
Refracting telescope uses lens to magnify images. The lens bend light as it travels through it.

13. What Instruments Detect Invisible Light?
Eye—detects visible light
Telescopes made to detect other waves than visible light
Different information can be gathered by making observations of each part of electromagnetic spectrum

14. How do we get information from space?
Probes and satellites that go beyond Earth’s atmosphere
Satellites and probes are unmanned space crafts
Space shuttle manned space craft
Hubble Space Telescope—orbits above most of Earth’s atmosphere

15. What would life on a space flight be like?
Survival Requires: water, food, oxygen

16. What have we done in space so far?
Sputnik-1: First artificial satellite
1957
USSR
Apollo-II: First human landing on the moon
1969
USA

18. Lesson 2: Earth and Sun Terms: Rotation Standard Time Zone
International Date Line
Revolution

19. How Do We Know Earth is Rotating?
Earth rotates on its axis
(Axis—imaginary line through the Earth from N Pole to S Pole)
24hours for Earth to make one rotation
Evidence
Satellite Images from Space
Foucault pendulum
Earth’s shape
“Movement” of the Sun—rises in east and sets in west

21. What Are Standard Time Zones?
Earth spins to the East
Rotates 360 degrees in 24 hours—15degrees/hr
Standard Time Zone: a belt 15 degrees wide in longitude—places all have same time
One-hour time zone that are next to each other
Travel west turn back (subtract)
Travel east turn forward (add)
International Date Line: location where new day begins—180 degrees line of longitude

23. Why Are There Seasons?
Seasons NOT caused by change in distance from the Sun
Revolution: Earth’s one trip around the Sun
Earth is tilted at 23 ½ degrees
Revolution of the tilted Earth around the Sun causes the Seasons
When N. Hemisphere is tilted towards the Sun—N. Hemisphere has summer
When N. Hemisphere is tilted away from the Sun—N. Hemisphere has winter

25. Where is the Sun in the Summer and in Winter?
Steeper the angles of Sun’s rays the higher the Sun appears in the sky
One side of the Earth experiences day while the other experiences night
Tell time by knowing position of the Sun in sky

26. How is the Sun an Important Energy Source?
Sun is the energy source for life on Earth
Plants convert sunlight to sugar (Producers)
Animals eat plants for energy (Consumers)
Fossil Fuels (coal, oil, natural gas) formed from decayed ancient living things
Sun is energy source for water cycle
Uneven heating of Earth’s surface causes wind and contributes to ocean currents

28. Lesson 3: The Moon In Motion
Terms:
Phase
Lunar Eclipse
Solar Eclipse
Tide

29. Why Does the Moon Change Its Appearance?
Moon revolves around Earth
Earth revolves around the Sun
Moon’s appearance changes appearance on monthly cycle
Phase: shape of the lighted part of the moon

30. Why Does the Moon Change Its Appearance?
Half of the Moon always lighted by the Sun
Can’t always see all half
The position of the Sun, the Moon, and Earth determine the phase

31. Why Does the Moon Change Its Appearance?
Half of the Moon always lighted by the Sun
Can’t always see all half
The position of the Sun, the Moon, and Earth determine the phase

32. Why Does the Moon Change Its Appearance?
New Moon: Moon between Earth and Sun
Cannot see any of the Moon’s lit half
Waxing Phase: more than New Moon but less that first quarter; “growing larger”
Waning Phase: less than full Moon phase but more than third quarter; “growing smaller”

33. What Are Eclipses?
Twice a year the Moon crosses the path of Earth’s orbit
Lunar Eclipse: Moon becomes dark for time until it moves out of Earth’s shadow

34. What Are Eclipses?
Solar Eclipse: Earth passes through Moon’s shadow; Moon must be in straight line between Sun and Earth

35. What are tides?
Tides: regular rise and fall of water levels along a shore
Tide caused from pull between Earth and Moon

36. What are tides? Spring tide: higher than usual tide
Neap tide: lower than usual tide

37. What Does the Moon’s Surface Look Like?
Observations made by telescopes and astronauts
Crater: formed by impact of space objects
Maria: large, dark flat areas
Highlands: light-colored cratered area at high levels
Mountains: named after Earth’s mountain ranges
Valleys: cigar-shaped depresions