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Chapter 27

Chapter 27. The Sun – Earth – Moon System. 27.1 – Tools of Astronomy. Electromagnetic radiation is the radiation from distant bodies throughout the universe that scientists study.

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Chapter 27

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  1. Chapter 27 The Sun – Earth – Moon System

  2. 27.1 – Tools of Astronomy • Electromagnetic radiation is the radiation from distant bodies throughout the universe that scientists study. • Electromagnetic spectrum – all types of electromagnetic radiation, arranged according to wavelength and frequency.

  3. Red light has longer waves lengths than blue light. • Radio waves have longer wavelengths than gamma rays. • Visible light falls between radio waves and gamma rays.

  4. Objects in space emit radiation in all portions of the electromagnetic spectrum. • Telescopes give us the ability to observe wavelengths beyond what the human eye can detect.

  5. There are several types of telescopes. • Refracting – uses a series of lenses to bring visible light into focus (1600). • Reflecting – uses a series of mirrors to focus light (1668). • Radio – gathers non-visible wavelengths (gamma rays, x rays, radio waves). • Hubble space – orbits Earth every 97 minutes (1990) • Page 768 lists other space telescopes

  6. Interferometry – a technique that uses several images to produce a single image (an enhanced image). • Human spacecraft • Spinoff technology – heart pumps (space shuttles fuel pumps) 1400 different technologies have been passed on to commercial industries.

  7. 27.2 – The Moon • The first steps to reaching the moon were taken in 1957 by the Soviet Union, with the launching of Sputnik I. • That same year, the United States launched the first American into space (Alan B. Shepard).

  8. The moon is 386,000 km away. It rotates on its axis and revolves around the Earth. This makes it a difficult task to reach. • Escape velocity 11 km/s (25,300 mph) • Position of moon at launch • Position of moon at arrival • Firing times of the rockets • 110 M tall and nearly 3 million kg at lift off (1 kg = 2.2 lbs.)

  9. In 1961 President Kennedy made it a national goal to put a man on the moon and return him safely. • Apollo 11 accomplished this goal in 1969. Neil Armstrong and Edwin Aldrin Jr. became the first people to walk on the moon. • There were six Apollo missions that landed on the moon (Apollo missions 11-12, 14-17).

  10. Lunar facts • Gravity is 1/6 that of Earth • Diameter is 3,476 km (Earth is 12,742 km) • Density is 3.3 g/cm3 (Earth is 5.515 g/cm3) • Mass is 1/8 that of Earth

  11. Lunar surface • Maria – dark smooth plains • Highlands – heavily cratered regions • Rays – materials blasted out of a crater • Rilles – meandering valley like structures • Regolith – lunar soil

  12. The moon does have a layered structure similar to Earth. • The moon is believed to have been formed when a Mars sized object struck the Earth and a large piece was ejected into space only to be caught in Earth’s gravitational pull.

  13. 27.3 – The Sun-Earth-Moon System • Earth – one day is 23 hrs. 56 min., and a year is 365 ¼ days. • Ecliptic plane – the path the Earth takes around the sun. • The axis of Earth is tilted at 23 ½ degrees. This tilt provides us with our four seasons.

  14. Solstices – the longest day and shortest day of the year. • Winter solstice is Dec. 21st or 22nd(least amount of sunlight in a day). • Summer solstice is June 21st or 22nd(greatest amount of sunlight in a day).

  15. Equinoxes – when daylight hours equal night time hours. • Autumnal equinox is around September 21st. • Spring equinox is around March 21st.

  16. Moon Phases • Waxing – as the moon changes from dark to light. • Waning – as the moon changes from light to dark. • Crescent – ¼ of the moon • Gibbous – ¾ of the moon • 1st quarter – ½ moon • 3rd quarter – ½ moon

  17. Synchronous rotation – the moon’s orbital and rotational periods are the same (one side is always dark, and one side is always light). • It takes 27.3 days to orbit the Earth. • The moon rises and sets 50 minutes later each day (tides).

  18. Tides – the rise and fall of the oceans due to the moon’s gravity (chapter 15). • Spring and Neap tides discussed in chapter 15.

  19. Solar eclipse – occurs when the Moon passes directly between the Sun and the Earth and blocks the Sun from view. • The Moon’s orbit is tilted at 5 degrees. This is the reason for partial eclipses

  20. Perigee – the closest point in the Moon’s orbit to Earth. • Apogee – the farthest point in the Moon’s orbit to Earth.

  21. Lunar eclipse – occurs when the Moon passes through Earth’s shadow. As sunlight passes Earth, it is refracted and this light gives the Moon a reddish color. • Umbra – total shadow of the Earth. • Penumbra – a partial shadow of the Earth.

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