Non-optical telescopes Flashcards
In what ways are radio telescopes similar and differences to optical telescopes??
Parabolic dish works the same as objective mirror of a optical reflecting telescope
Antenna used as detector at focal point instead of eye
Manoeuvrable
How big are radio waves compared to light?
About a million times longer
How big would a radio telescope need to be to have the same resolving power as an optical telescope?
How do scientists get around this?
A million times bigger
Linking lots of them together
What is used in a radio telescope instead of the polished mirror of an optical telescope?
Wire mesh
What advantages are there of using wire mesh?
Construction is cheaper and easier
Why does the dish shape of a radio telescope have to have a precision of λ/20 ?
To avoid spherical aberration
What is the biggest problem with doing astronomy on earth?
Atmosphere stops certain wavelengths from coming through
What 2 waves can be observed on the surface of the earth?
Optical ( a little UV and a little IR)
Radio
Where is the best place to observe infrared radiation?
High and dry places
How do you detect X-rays and Ultra violet radiation?
Strap the UV and X-Ray telescopes to weather balloons or aeroplanes
Where is the ideal place to put your telescope?
In space
How are IR and UV telescopes similar to optical reflecting telescopes?
Use the same parabolic mirror
What’s the same about UV and IR telescopes?
Both use CCDs as radiation detectors
And both use parabolic mirrors
The longer the wave length the ….. its effected by imperfections
Less
How precise does the mirror shape in IR telescopes need to be and why?
Not as precise
Because it’s has a long wavelength so is affected less by imperfections
How precise does the mirror shape in UV telescopes need to be?
More precise
Because it’s has a shorter wavelength so is affected more by imperfections
What’s the problem with IR telescopes that does effect any other type of telescope?
It creates its own infrared radiation so needs to be cooled to very low temperature using liquid helium or refrigeration units
What’s different about X-Rays compared to other EM radiation?
Don’t reflect of surfaces.
They are usually either absorbed or pass straight through it
When do X-Rays reflect?
If they just graze a mirror surface
Explain how a grazing telescope works
A series of nested mirrors to gradually change the direction of X-Rays to bring them to focus on a detector
What are X-Rays detected by?
Modified Geiger counter or fine wire mesh
