The Sun-Earth-Moon System

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: • 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 • 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 • Heavily cratered regions of the moon • Light colored • Maria • Dark smooth plains with few craters

23. Lunar Craters • Impact craters • 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 • 3.8-4.6 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 • 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. 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 • Causes the Coriolis effect • Day Length • 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 • 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