Space Exploration
Teacher Outline
* Teacher Outline included in Teacher Guide Download

1. Early civilizations - observations with eyes only allowed for more philosophical arguments than science

1. Greeks held the geocentric view of the universe (Ptolemy)
     
2. Aristarchus, early Greek who first said that the Earth may have been sun-centered or Heliocentric
     
3. Other civilizations chartered stars and recorded them, but early civilization had little tools to look at the heavens

2. 15^th and 16^th Centuries

1. Copernicus - reconstructed the heliocentric theory and how the solar system moved, but still did not use many instruments
     
2. Tycho Brahe - used wall quadrant and sextant that measured star locations
     
3. Johannes Kepler - developed 3 laws of planetary motion

3. 17^th to 19^th Centuries

1. Galileo - invented the refracting telescope
     
2. Sir Isaac Newton used reflecting telescope; also produced a continuous spectrum which was later the bases on developing the following different principles

1. Continuous spectrum is produced by an incandescent solid, liquid or gas under high pressure
     
2. Bright line or emission spectrum produced by an incandescent gas under low pressure
     
3. Dark-line or absorption spectrum is produced when white light is passes through a gas under lower pressure, where most stars fit
     
4. Can interpret history and other scientific information from stars just through observation

3. Thomas Wright and William Herschel discovered Uranus using a telescope; first planet to be discovered that cannot be seen by sight

4. 20^th and 21^st Centuries

1. Radio telescopes
    
2. Other types of space telescopes, including Hubble, FIRST, New Generation of Space Telescopes

1. Need understand properties of electromagnetic radiation in order to create different types of telescopes

1. Difficult because electromagnetic radiation (including light, x-rays, radio waves, etc) behave sometimes as waves and sometimes as particles
     
2. In development of telescope, light was most important in design

2. Refracting telescopes

1. most important lens in telescope is the objective, which produces the image; it can focus an object

1. You can demonstrate by holding a lens in one hand and with the other hand place a white card behind the lens, vary the distance between the card and lense until the image appears on the card, the distance to make the object in focus is called the focal length of the lens

2. When viewing individual stars, astronomers are more interested in the light gathering power of their instruments than in magnification

1. Telescopes with larger objectives can "see" further into space; these telescopes have a better "resolving power" or ability to see more details

3. Reflecting telescopes

1. Use a concave miro that focuses the light in front of the objective rather than behind it like a lens
     
2. Mirror is generally made of glass that is finely ground
     
3. reflectors cannot survey large sections of the sky, they have a narrow field of view
     
4. Can build more powerful telescopes, smaller than a refracting telescope, so reflectors are more commonly built in research

1. Need speed of 25,000 miles per hour to get into space

1. Development of rockets from Chinese 1000 years ago to Germans in early 1900's led the way for space travel

2. Sputnik (fellow travelers) I, in 1957 was first satellite to be launched from Earth by Russians
     
3. Explorer I, in early 1958 was first American; NASA (National Aeronautics and Space Agency) was established by congress and has grown into the space agency that guides most space explorations
     
4. Man in space needed the following requirements to consider:

1. Air environment in space craft and outside
     
2. G- force considerations (keep acceleration (increase of speed as you blast off) and deceleration (stopping and weightlessness) forces within tolerable limits
     
3. Eating and other living functions on a space station

5. Space telescopes and communication satellites