Unit E: Space Exploration

Transcription

1 Unit E: Space Exploration Science Human understanding of both and has changed over time. Egyptian wall paintings Aristotle s geocentric model Curiosity rover landed on Mars on August 6,

2 1.1 Early Views About the Cosmos in the sky have fascinated humans throughout time. The of how these celestial objects came to be are even more fascinating. A. Ancient Views of the Cosmos 1. Myths, folklore and legends were used to explain what ancient people in the night sky. a) First Nations people of the Pacific Northwest - believed the night sky was a pattern on a great overhead, which was held up by a spinning 'world pole' resting on the chest of a woman named Stone Ribs. 2

3 B. Solstice 1. Represents the and periods of daylight 2. solstice - shortest period of daylight (Northern hemisphere - Dec. 21) 3. solstice - longest period of daylight (Northern hemisphere - June 21 ) 4. The set up megaliths, in concentric circles, at to mark the winter and summer solstices. 5. Ancient African cultures set large rock into patterns to predict the timing of the solstices as well. 3

4 C. Equinox 1. Represents periods of equal day and night 2. equinox occurs in the fall (Northern hemisphere Sept. 22) 3. equinox occurs in the spring (Northern hemisphere Mar. 21) 4. The Mayans of Central America built an enormous cylinder shaped tower, at Chichen Itza, to the two equinoxes. 5. The built many pyramids and other monuments to align with the seasonal position of certain stars. 6. Aboriginal Peoples of Southwestern Alberta used key rocks, which aligned with certain stars, in their medicine circles. cultures tried to explain the motions of the stars and planets. 4

5 D. Models of Planetary Motion 1. Aristotle s Model 2. Copernicus Model 5

6 1.2 Discovery through Technology Imagination, and improvements in observation instruments and tools, Ancient Astronomy into a more precise scientific understanding of the heavens A. Looking With the Naked Eye 1. The earliest astronomers used several to chart the position of objects in the sky and to predict where the sun, moon, and certain stars would move. 2. With the heavens serving as both timekeeper and navigational aid, such was of much more than scholarly interest. Astrolobe 6

7 B. Early Telescopes 1. Before 1609, when Galileo began using a brand new invention called the, humankind's perception of the cosmos was limited to what could be seen with the naked eye. 2. It was natural to perceive Earth as the of the universe, with a transparent, starry sphere rotating around it. C. Quadrant 1. Tycho Brahe was an observation genius in before the age of the telescope. 2. The mural, or Tychonian, quadrant was actually a very brass quadrant, affixed to a wall. 3. Its radius almost two meters. 4. Sightings were taken along the quadrant through the small in the opposing wall, to which Tycho points. 7

8 D. Armillery Sphere 1. Was used to locate objects. 2. As measuring devices became more and more, old notions about the universe began to crumble. 3. For example, Brahe's measurements, even though they were made with the naked eye, were fine enough to reveal that move through the same region of space as the planets. 4. That destroyed the idea that planets occupied a special that no other object could penetrate. E. Astrolabe 1. The astrolabe is the instrument used to observe the and determine their position on the. 2. It had two parts. a) The had a moveable sighting arm and a scale for measuring altitude. b) The had a map of the heavens that helped to calculate the future position of objects. 3. With this device, astronomers and others could when the sun and certain bright stars would rise or set on any given day. 4. Ipparch invented the astrolabe in the 2nd century B.C. Ptolemy used the astrolabe as a type of geographical map. They were later used to tell time. 5. In the Middle Ages the astrolabe was the main instrument for later to be replaced by the sextant. 8

9 F. Sextent 1. A sextant is a tool for measuring the angular of a star above the horizon, which was usually the sun. 2. Primarily, they were used for. 3. This instrument can be used to measure the of a celestial body from aircraft, spacecraft or the ship's deck. 4. The main types are the sextant used for ships and the bubble sextant used only on aircraft. G. Cross-staff 1. The cross-staff was made up of a straight staff, marked with graduated scales, with a closefitting, sliding. 2. The navigator rested the staff on his and lined up one end of the moving crosspiece with the horizon and the other end with the bottom of the pole star, or the sun at midday. 3. The position of the cross piece on the staff gave the reading of. 9

10 H. Astronomical Unit 1. The astronomical unit is used for measuring 'local' distances in the system. It is equal to the distance from the center of the Sun to the center of the (approximately 149,599,000 kms). See Page 379 I. Light Year 1. A light year is equal to the light travels in 1 year (approximately 9.5 trillion kms). It is used for longer distances - to stars and galaxies. 2. The distance to our nearest star, Proxima Centauri is a little over light years. Stephan s Quintet 280 million light years away 10

11 J. Parsec 1. A parsec is a basic unit of length for measuring distances to stars and galaxies, equal to times the distance from the earth to the sun, or 3.26 light-years. 2. The nearest star, Proxima Centauri is about parsecs from the Earth. K. Looking Into The Past 1. When you view an object in the sky you are seeing it as it was in the. It has taken the light a very long time to reach the Earth. 2. Light from the Sun takes about minutes to reach the Earth, whereas light from Pluto takes about hours. The farther away, the longer light takes to reach the Earth. 3. Light from the stars in the center of the universe takes about years to reach the Earth. The Hubble telescope is capturing light from billion years ago. 1.3 The Distribution of Matter in Space A star is a hot, glowing ball of gas (mainly and ) that gives off light energy. Stars vary in their. Very hot stars look, while cooler stars look. In the 1920's, Ejnar Hertzsprung and Henry Norris Russell compared the surface of stars with its brightness (luminosity). 11

12 Hertzsprung-Russell (H-R) diagram 90% of all stars fit into the same grouping as our A. Birth of Stars 1. Stars form in regions of space where there are huge accumulations of gas and dust called. 2. Interstellar matter, which makes up part of the nebulae, originated from stars. 3. The process of 'star-building' is known as fusion, which releases great amounts of and radiation. 12

13 B. Star Groups 1. Constellations a) Constellations are the of stars we see as patterns in the night sky. There are 88 constellations and many are explained in Greek Mythology. 2. Asterisms a) Asterisms are also groupings of stars but are not officially as constellations. i. Example: C. Galaxies 1. A galaxy is a grouping of or of stars, gas and dust. a) It is held together by. b) The Milky Way Galaxy is the galaxy our solar system is a part of. c) It is shaped like a flattened, with arms spiraling out from the center. 2. are actually invisible to telescopes. Their existence is only known by an indirect method - when celestial material comes close to a black hole it becomes very hot and very bright. 13

14 1.4 Our Solar Neighborhood A. The emits charged particles in all directions. This solar wind bombards the Earth at 400km/s, but the field of the Earth protects us. B. The Planets 14

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17 C. The formation of our solar system is based on the ', which follows three steps: 1. A cloud of gas & dust in space begin 2. Most of the matter (more than 90% of it) in the center - forming the Sun 3. The remaining materials accumulate (forming planets) and the Sun D. Other Bodies in the Solar System 1. a) A narrow belt of small, rocky or metallic bodies travelling in space between the orbits of Mars and Jupiter. b) Scientists are not certain where they come from 2. Comets a), made up of dust and ice b) Tail and bright glow only visible when they are close to the sun Halley s Comet 17

18 3. Meteoroids a. Small pieces of rocks flying through space with no particular. 4. Meteor a. When a meteoroid gets pulled into the atmosphere by Earth s, the heat of atmospheric friction causes it to give off light and is known as a meteor. 5. Meteorite a. If a meteor lasts long enough to hit the Earth s, it is called a meteorite. E. Tracking Objects in the Solar System 1. paths can help Astronomers and scientists to trace and predict where bodies in space are, have been and will be in the future. 2. The understanding of orbits has led to the discovery of many different. 3. tracks asteroids, comets and meteors that have been discovered by observatories and amateur astronomers. 18

19 1.5 Describing the Position of Objects in Space A. Altitude and Azimuth are from the observer's position: 1. Altitude a) Gives you the "how high above the it is. b) The point straight has an altitude of +90 degrees. c) Straight, an altitude of -90 degrees. d) Points on the horizon have degree altitudes. e) An object up in the sky has an altitude of 45 degrees. 2. Azimuth a) Determines "which direction it can be found in the sky." b) An azimuth of zero degrees puts the object in the. 19

20 c) An azimuth of 90 degrees puts the object in the. d) An azimuth of 180 degrees puts the object in the, and one of 270 degrees puts the object in the. 3. Zenith a) Is the in the sky directly overhead. 4. Thus, if a guide tells you that an object is at altitude degrees, azimuth degrees, look a little North of due East, about a third of the way from the horizon to the zenith. 5. Ecliptic a) The path in the sky along which the takes 20

21 6. Celestial a) Is the name given to the very large 'sphere of sky' surrounding the Earth. 21