Term
3A-1
When is it probable that people first studied stars and grouped them into constellations? |
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Definition
| Following the Flood, constellations are mentioned in the book of Job (38:31-32), which records events in the life of a man who probably lived before Abraham. |
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Term
3A-2
What two benefits did knowledge of the heavens give to early civilizations? |
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Definition
| To guide travelers and to keep accurate calendars. |
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Term
3A-3
What name was given to an early device that was used to indicate time and seasons by the shadow it cast in sunlight? |
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Definition
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Term
3A-4
What was the above instrument called when a numbered dial was added? |
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Definition
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Term
3A-5
What early work used by Copernicus and Tycho contained a catalog of stars? Who was the author? |
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Definition
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Term
3A-6
(True or False) Ancient astronomers could accurately time the sun's motion with a sundial. |
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Definition
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Term
3A-2
Who was the first astonomer to build a telescope for viewing the heavens? |
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Definition
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Term
3A-2
What does the word refract mean? |
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Definition
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Term
3A-2
What are the three functions of a telescope? |
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Definition
| light gathering, magnification and to bring out details in an image |
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Term
3A-2
What does a refractor telescope use to accomplish these three functions? |
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Definition
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Term
3A-2
What is the color distortion caused by lenses called? |
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Definition
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Term
3A-2
Give two ways to reduce this color distortion? |
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Definition
1) use thin objective lenses that did not bend light enough to cause distortion
2) use of compound lenses which focus the colors at the same time |
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Term
3A-2
(True or False) Binoculars using multiple lenses to magnify an image are similar in the way they work to a refractor telescope. |
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Definition
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Term
3A-3
Who developed the first reflector telescope? |
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Definition
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Term
3A-3
What does the reflector telescope use to accomplish the three functions of a telescope? |
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Definition
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Term
3A-3
What type of reflector telescope is viewed from the same position as a refractor telescope? |
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Definition
| the Cassegrainian reflector |
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Term
3A-3
How is the size of a reflecting telescope indicated? Why is this important? |
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Definition
| by the diameter of its concave mirror; the larger the diameter, the greater the light-gathering power and resolution of the telescope |
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Term
3A-3
List the three advances in mirror design that made the modern giant telescopes possible. |
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Definition
1) honeycomb mirror
2) segmented mirrors
3) meniscus mirror |
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Term
3A-3
A telescope that uses both a corrective objective lens and mirrors to gather light is called by what name? |
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Definition
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Term
3A-3
(True or False) The Cassegrainian telescope is easier for amateurs to use than other forms of reflecting telescopes. |
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Definition
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Term
3A-4
Name a common type of nonoptical telescope in use on the earth today. |
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Definition
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Term
3A-4
How can nonoptical telescopes detect the kinds of nonvisible light rays that are filtered out by the atmosphere? |
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Definition
| With the use of satellites that are put into orbit above our atmosphere. |
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Term
3A-4
Discuss two ways a radio telescope can be used. |
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Definition
1) separate radio telescopes that are far apart can work together to form a sharper picture of a celestial object;
2) they can send and receive radio waves |
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Term
3A-4
Name three advantages of having a telescope in orbit above the earth's atmosphere. |
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Definition
1) its location in orbit high above Earth's atmosphere, which distorts and absorbs much of the enrgy emitted by celestial objects. It has gathered a tremendous amount of data about our solar system, our Milky Way galaxy, and our universe.
2)it uses the near-infrared and ultraviolet regions of the spectrum to "see" objects that are otherwise invisible because they are hidden behind clouds of dust.
3) its ability to photograph stars and other astronomical objects that are so distant, or so lacking in absolute brightness, that they have never beenphotographed before. |
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Term
3A-4
List three types of common amateur telescope mounts. |
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Definition
| altazimuth, German or equatorial mount, Debsonian mount |
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Term
3A-4
How are images from optical telescopes most often recorded? |
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Definition
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Term
3A-4
What kind of camera is replacing photographic film cameras in astronomical applications? What is the technical name for the part of the camera that has taken the place of film? |
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Definition
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Term
3A-4
How are images from radio telescopes most often recorded? |
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Definition
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Term
3A-4
Name two important star catalogs. |
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Definition
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Term
3A-4
(True or False) An altazimuth mount would be the easiest mount to use to track a specific star over a period of several hours. |
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Definition
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Term
3A
What is a constellation? |
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Definition
| stars grouped into patterns |
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Term
| What is Stonehenge? What was it used for? |
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Definition
| Stonehenge is a ring of stones found in England. It was an early observatory for determining celestial events such as solstices and equinoxes. |
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Term
| Describe Galilei's telescope. |
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Definition
| It consisted of two lenses, one mounted at each end of a tube that could be adjusted in length to focus the image. It was a refractor telescope because it used only lenses to magnify an image. |
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Term
| How do the lenses on a refracting telescope work? |
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Definition
| the first lens refracts the light from the planet to concentrate the light as a small image, and the second lens refracts the light to magnify that image. |
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Term
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Definition
| the ability of a telescope to bring out details in an image. |
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Term
| What did Sir Isaac Newton discover about white light? |
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Definition
| He discovered that white light is made up of various colors. |
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Term
| As news of Galileo's telescope spread, and other scientists began making telescopes with greater and greater magnification, what problem did they encounter with the refractors? |
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Definition
| As they obtained greater magnification, the lenses produced a blurry fringe of color around the image, called chromatic aberration. |
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Term
| What is a reflector telescope and who invented it? |
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Definition
| A reflector telescope replaces the refractor's light-gathering objective lens with a mirror. His first telescope reflected light from a concave mirror at the lower end of the tube and formed an image near the upper end of the tube. A flat mirror there reflected the image through a hole inthe side of the tube, where the ocular magnified containing lenses was attached to receive the image. This arrangement, in which the image is viewed through the side of the tube, is called a Newtonian reflector. |
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Term
| What two things does the Newtonian reflector avoid? |
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Definition
| chromatic aberration and the side reflection or absorption that incoming light experiences in the large glass lenses of a refractor. |
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Term
| Why is the size of refractor telescopes limited? |
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Definition
| The large glass lenses must be supported around the edges, sag from the force of gravity limits their size. |
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Term
| Give 2 advantages of the reflector telescope? |
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Definition
| 1) their mirrors can be supported from behind so they can be built much larger; 2) the mirrors can be easily ground in a parabolic curve that eliminates all forms of chromatic and spherical aberration. |
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Term
| What is spin-casting and which mirror type is it used with? |
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Definition
| Spin-casting is the process used to produce a single-piece glass mirror over a honeycomb-shaped structure. It is used with the honeycomb mirror. |
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Term
| Describe a segmented mirror? |
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Definition
| It is composed of 36 aluminum-coated metal mirrors that fit together like hexagonal tiles to make a mirror. |
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Term
| Describe a meniscus mirror. |
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Definition
| A single-piece made of glass so thin that it needs computer-controlled actuators to keep the mirror in the proper shape. These mirrors rest on a bed of sensor-controllled actuators that constantly push or pull on the mirror. |
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Term
| What other energy do stars produce in other regions of the electromagnetic spectrum? |
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Definition
| They emit radio waves, infrared waves, ultraviolet rays, x-rays, and gamma rays. |
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Term
| Astronomers use other kinds of telescopes to observe what? |
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Definition
| infrared waves, ultraviolet rays, x-rays, and gamma rays |
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Term
| What do astronomers analyze to learn more about a star? |
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Definition
| the electromagnetic energy that it emits |
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