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TelescopesTelescopes
Mr. HibbettsMr. Hibbetts
Special thanks to Dr. Dan Bruton, Special thanks to Dr. Dan Bruton, Astronomy and Physics SFAAstronomy and Physics SFA
Telescope OpticsTelescope OpticsLensesLenses
MirrorsMirrors
Refraction...Refraction...
……is the bending of light rays upon is the bending of light rays upon passing from one transparent medium passing from one transparent medium to another.to another.
ConvexConvex and and concaveconcave lenses refract lenses refract light.light.
Reflection...Reflection...
……is the rebounding of light rays off a is the rebounding of light rays off a smooth surface (diffuse or specular).smooth surface (diffuse or specular).
ConvexConvex and and concaveconcave mirrors reflect mirrors reflect light.light.
Convex – bending or curving outwardConvex – bending or curving outward
Concave – bending or curving inwardConcave – bending or curving inward
Focal PointFocal Point the place where light rays converge to a pointthe place where light rays converge to a point
Focal LengthFocal Length the distance from a curved mirror or lens to its the distance from a curved mirror or lens to its
focus focus
Types of TelescopesTypes of TelescopesRefracting Telescope Refracting Telescope Reflecting TelescopeReflecting TelescopeCassegrain TelescopeCassegrain Telescope
Refracting TelescopeRefracting Telescope (Galilean) (Galilean)
objective lens objective lens
Eyepiece lensEyepiece lens
Typical Small RefractorTypical Small Refractor
Reflecting Telescope Reflecting Telescope (Newtonian)(Newtonian)
a concave primary mirrora concave primary mirror
flat secondary mirrorflat secondary mirror
eyepieceeyepiece
6-inch Newtonian Telescopes6-inch Newtonian Telescopes
Earl of Rosse’s LeviathanEarl of Rosse’s Leviathan
Cassegrain TelescopeCassegrain Telescope
a concave primary mirrora concave primary mirror
a convex secondary mirrora convex secondary mirror
eyepiece lenseyepiece lens
SFA ObservatorySFA Observatory
Cassegrain TelescopesCassegrain Telescopes
41” Telescope41” Telescope
18” Telescope18” Telescope
10-inch Schmidt-Cassegrain10-inch Schmidt-Cassegrain
Multiple Mirror TelescopeMultiple Mirror Telescope
Types of TelescopesTypes of Telescopes
What are the 3 types of What are the 3 types of Telescopes?Telescopes?
Why use a telescope?Why use a telescope?
BrightenBrightenMagnify Magnify ResolveResolve
Light Gather PowerLight Gather PowerHighLow
ResolutionHighLow
Magnification
HighLow
Light Gathering PowerLight Gathering Power
10.7 cm camera
15.2 cm camera
Telescopes MagnifyTelescopes MagnifyMagnificationMagnification - the number of times - the number of times
larger an object appears through a larger an object appears through a telescope than as seen by the naked telescope than as seen by the naked eyeeye
Eyepiece theofLength FocalMirroror Lens Objective theofLength FocalionMagnificat
ResolutionResolution
What makes a telescope What makes a telescope great?great?
Light Gathering PowerLight Gathering PowerLarge DiameterLarge Diameter
MagnificationMagnificationLong focal length for the primary lens or Long focal length for the primary lens or
mirrormirror Resolving PowerResolving Power
Large diameterLarge diameterQuality Lenses / MirrorsQuality Lenses / Mirrors
Why use a telescope?Why use a telescope?
BrightenBrightenMagnify Magnify ResolveResolve
On Earth, there are two major types of On Earth, there are two major types of telescopes used:telescopes used:
Common Optical TelescopesCommon Optical TelescopesRadio TelescopesRadio Telescopes
The The Earth’s atmosphereEarth’s atmosphere is mostly is mostly transparent for transparent for visible lightvisible light and and radio radio waveswaves..
Earth’s AtmosphereEarth’s Atmosphere
The Hubble Space The Hubble Space Telescope...Telescope...
……is the largest telescope in space.is the largest telescope in space. ...is 30 times more sensitive than ...is 30 times more sensitive than
ground based telescope.ground based telescope. ...orbits the Earth every 95 minutes....orbits the Earth every 95 minutes. ……gives gives high resolutionhigh resolution images because images because
it does not suffer from the effects of it does not suffer from the effects of atmospheric turbulence.atmospheric turbulence.
M100M100
Cat’s Eye NebulaCat’s Eye Nebula
Hubble Deep FieldHubble Deep Field
Kepler TelescopeKepler Telescope Launched in March 2009Launched in March 2009
Mission is to find Earth-like planets Mission is to find Earth-like planets around other starsaround other stars
Has the most resolute camera every Has the most resolute camera every constructedconstructed
Has confirmed hundreds planets Has confirmed hundreds planets and found over 2,300 candidatesand found over 2,300 candidates
Mission officially ended in August Mission officially ended in August 2013 after two motors failed2013 after two motors failed
Chandra and SpitzerChandra and SpitzerOther important NASA telescopesOther important NASA telescopesFocus on X-Ray / Gamma Ray imagesFocus on X-Ray / Gamma Ray images
Observing ProblemsObserving ProblemsWhat are some problems that prevent What are some problems that prevent
good telescope viewing?good telescope viewing?
Observing ProblemsObserving Problems Bad WeatherBad Weather Light PollutionLight Pollution DispersionDispersion ScintillationScintillation
a.k.a. “bad seeing”a.k.a. “bad seeing”This effect can be reduced with adaptive This effect can be reduced with adaptive
optics.optics.
SeeingSeeing is the measure of the steadiness of is the measure of the steadiness of an object in the Earth’s atmosphere during an object in the Earth’s atmosphere during astronomical observations.astronomical observations.
Adaptive OpticsAdaptive Optics allows astronomers to allows astronomers to correct for atmospheric distortions in correct for atmospheric distortions in images.images.
Mount Wilson ObservatoryMount Wilson Observatory
The 100” TelescopeThe 100” Telescope
Writing AssignmentWriting Assignment Imagine you are explaining the telescopes Imagine you are explaining the telescopes
you just demoed to a friend or family you just demoed to a friend or family member. Explain how they enhanced your member. Explain how they enhanced your vision and any interesting things you vision and any interesting things you noticed. noticed.
Which optic device did you find to be the Which optic device did you find to be the most useful and like the most? Explain most useful and like the most? Explain your reasons why.your reasons why.
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