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ASTRONOMY 101
CHAPTER 4
42
Astronomy
Undergraduate 1
08/28/2007

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Term
ELECTROMAGNETIC RADIATION
Definition
LIGHT IS MADE UP OF BOTH ELECTRIC AND MAGNETIC FIELDS.
Term
WAVELENGTH
Definition
THE DISTANCE BETWEEN PEAKS
Term
NANOMETER (nm)
Definition
TOO AWKWARD TO MEASURE SUCH SHORT DISTANCES IN MILLIMETERS, SO PHYSICISTS AND ASTRONOMERS DESCRIE THE WAVELENGTH OF LIGHT USING EITHER THE UNIT OF __
Term
ANGSTROM (A)
Definition
TOO ASKWARD TO MEASURE SUCH SHORT DISTANCES IN MILLIMETERS, SO PHYSICITS AND ASTRONOMERS DESCRIBE THE WAVELENGTH OF LIGHT USING EITHER THE UNIT OF BILLIONTH OF AMETER (10-9 M)___WHICH IS NAME AFTER THE SWEDISH ASTROMERS ANDERS ANGSTROM
Term
INFRARED (IR)
Definition
RADIATION, WITH WAVELENGTHS RANGING FROM 700 nm TO ABOUT 1 mm
Term
ULTRAVIOLET (UV)
Definition
ELECTROMAGNETIC WAES WITH WAVELENGTHS SHORTER THAN VIOLET LIGHT ARE CALLED
Term
X-RAYS
Definition
SHORTER-WAVELENGTH ELECTROMAGNETIC WAVES THAN UV ARE CALLED
Term
GAMMA RAYS
Definition
ARE THE SHORTEST WAVELENGTH ELECTROMAGNETIC WAVES THAN UV ARE CALLED
Term
PHOTON
Definition
A MINIMUM SIZED BUNDLED OF ELECTROMAGNETI WAVES. A PARTICLE OF LIGHT IS CALLED
Term
ATMOSPHERIC WINDOWS
Definition
ONLY VISIBLE LIGHT, SOME SHORT-WAVELENGTH INFRARED RADIATION, AND SOME RADIO WAVES REACH EARTH'S SURFACE THROUGH WHAT ARE CALLED
Term
REFRACTING TELESCOPES
Definition
A TELESCOPE TO FOCUS LIGHT BY USING A LENS TO GATHER AND FOCUS THE LIGHT
Term
REFLECTING TELESCOPES
Definition
TELESCOPE USE TO FOCUS LIGHT USING A MIRROR
Term
PRIMARY LENS
Definition
THE MAIN LENS INA REFRACTING TELESCOPE
Term
PRIMARY MIRROR
Definition
THE MAIN MIRROR IN A REFLECTING TELESCOPE
Term
EYE PIECE
Definition
BOTH KINDS OF TELESCOPES FORM A SMALL, INVERTED IMAGE THAT IS DIFFICULT TO OBERSERVE DIRECTLY, SO A LENS CALLED THE ____ IS USED TO MAGNIFY THE IMAGE AND MAKE IT CONVENIENT TO VIEW.
Term
FOCAL LENGTH
Definition
IS THE DISTANCE FROM A LENS OR MIRROR TO THE IMAGE IT FORMS OF A DISTANT LIGHT SOURCE SUCH AS A STAR.
Term
CHROMATIC ABERRATION
Definition
TELESCOPES HAVE SERIOUS DISADVANTAGES. MOST SUFFER FROM AN OPTICAL DISTORTION THAT LIMISTS THEIR USEFULNESS. WHEN LIGHT IS REFRACTED THROUGH GLASS, SHORTER WAVELENGTHS BEND MORE THAN LONGER WAVELENGTHS. AS A RESULT YOU SEE A COLOR BLUR AROUND EVERY IMAGE. THIS COLOR SEPARATION IS CALLE ___
Term
OPTICAL TELESCOPES
Definition
TELESCOPE TO GATHER VISIBLE LIGHT
Term
RADIO TELESCOPES
Definition
TELECOPE TO GATHER RADIO RADIATION.
Term
LIGHT GATHERING POWER
Definition
REFERS TO THE ABILITY OF A TELESCOPE TO COLLECT LIGHT.
Term
RESOLVING POWER
Definition
REFERS TO THE ABILITY OF THE TELESCOPE TO REVEAL FINE DETAIL
Term
DIFFRACTION FRINGE
Definition
ONE CONSEQUENCE OF THE WAVELIKE NATURE OF LIGHT IS THAT THERE IS AN INEVITABLE SMALL BLURRING CALLED A ___AORUND EVERY POINT OF LIGHT IN THE IMAGE, AND YOU CAN'T SEE ANY DETAIL SMALLER
Term
INTERFEROMETER
Definition
ONE WAY TO IMPROVE RESOLVING POWER IS TO CONNECT TWO OR MORE TELESCOPES IN AN ___WHICH HAS A RESOLVING POWER EQUAL TO THAT OF A TELESCOPE AS LARGE AS THE MAXIUM SEPARATION BETWEEN THE INDIVIDUAL TELESCOPES
Term
SEEING
Definition
IN ADDITION, WHEN YOU LOOK THROUGH A TELESCOPE, YOU LOOK THROUGH MILES OF TURBULENCE IN EARTH'S ATMOSPHERE, WHICH MAKES IMAGES DANCE AND BLUR, A CONDITION THA ASTRONOMERS CALL
Term
ADAPTIVE OPTICS
Definition
A SITUATION CAN BE IMPROVED BY A DIFFICULT AND EXPENSIVE TECHNIQUE CALLED ____IN WHICH RAPID COMPUTER CALCULATIONS ADJUST THE TELESCOPE OPTICS AND PARTLY COMPENSATE FOR SEEING DISTORTIONS.
Term
MAGNIFIYING POWER
Definition
THE LEAST IMPORTANT POWER OF A TELESCOPE IS ____THE ABILITY TO MAKE AN IMAGE LARGE
Term
LIGHT POLLUTION
Definition
optical astronomers avoid cities because ____the brightening of the night sky by light scattered from artifical outdoor lighting,can make it impossible to see faint objects
Term
SIDEREAL TRACKING
(SIDEREAL, REFERS TO THE STARS)
Definition
TELESCOPES LOCATED ON THE SURFACE OF EARTH, WHETHER OPTICAL OR RADIO, MUS MOVE CONTINUOUSTLY TO STAY POINTED AT A CELESTIAL OBJECT AS EARTH TURNS ON ITS AXIS. THIS IS CALLED
Term
PHOTOGRAPHIC PLATE
Definition
WS THE FIRST IMAGE RECORDING DECISE USED WITH TELESCOPES.
Term
PHOTOMETERS
Definition
SENSITIVE LIGHT METERS TO MEASURE THE BRIGHTNESS OF INDIVIDUAL OBJECTS VERY PRECISELY.
Term
CHARGE COUPLED DEVICES (CCDs)
Definition
MOST MODERN ASTRONOMERS USE THIS AS BOTH IMAGE RECORDING DEVICES AND PHOTOMETERS
Term
ARRAY DETECTORS
Definition
CAN BE USED LIKE A SMALL PHOTOGRAPHIC PLATE, BUT THEY HAVE DRAMATIC ADVANTAGES OVER BOTH PHOTOMETERS AND PHOTOGRAPHIC PLATES.
Term
DIGITIZED
Definition
MEANING, CONVERTED TO NUMERICAL DATA, AND CAN BE READ DIRECTLY INTO A COMPUTER MEMORY FOR LATER ANALYSIS.
Term
FALSE COLOR IMAGES
Definition
ASTRONOMERS ALSO MANIPULATE IMAGES TO PRODUCE ____IN WHICH COLORS REPRESNT DIFFERENT LEVES OF INTENSITY AN ARE NOT RELATED TO THE TRUE COLORS OF THE OBJECT
Term
SPECTROGRAPH
Definition
TO ANALYZE LIGHT IN DETAIL, YOU NEED TO SPREAD THE LIGHT OUT ACCORDING TO WAVELENGTH INTO A SPECTRUM, A TASK PERFORMED BY A ___
Term
SPECTRUM
Definition
VIOLET (SHORT WAVELENGTH) LIGHT BENDS MOST, ANDRED (LONG WAVELENGTH) LIGHT LEAST. thURS, THE WHITE LIGHT ENTERING THE PRISM IS SPREAD INTO WHAT IS CALLED
Term
GRADING
Definition
IS A PIECE OF GLASS WITH THOUSANDS OF MICROSCOPIC PARALLEL LINES SCRIBED ONTO ITS SURFACE
Term
SECONDARY MIRROR
Definition
CAN REFLECT THE LIGHT THROUGH A HOLE IN THE PRIMARY MIRROR TO A CASSEGRAIN FOCUS
Term
PRIME FOCUS
Definition
IN LARGER TELESCOPES THE LIGHT CAN BE FOCUSED TO A ____POSITION HIGH IN THE TELESCOPE TUBE. ALTHOUGH, IT IS A GOOD PLACE TO IMAGE FAINT OBJECTS, THE PRIME FOCUS IN INCONVENIENT FOR LARGE INSTRUMENTS.
Term
CASSEGRAIN FOCUS
Definition
THIS FOCAL ARRANGEMENT MY BE THE MOST COMMON FORM OF ASTRONOMICAL TELESCOPE. IT IS CONVENIENT AND HAS ROOM FOR LARGE INSTRUMENTS
Term
NEWTONIAN FOCUS
Definition
SMALLER TELESCOPES CAN USE OTHER FOCAL ARRANGMENTS. THE ____THAT ISAAC NEWTON USED IN HIS FIRST REFLECTING TELESCOPE IS AWKWARD FOR LARGE TELESCOPES
Term
SCHMIDT-CASSEGRAIN FOCUS
Definition
MANY SMALL TELESCOPES SUCH AS THIS ONE HAS A THIN CORRECTING PLACE IMPROVING THE IMAGE BUT IS TOO SLIGHTLY CURVED TO INTRODUCED SERIUOS CHROMATIC ABERRATION
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