Telescopes Flashcards
What is magnification?
Focal length of objective/focal length of eyepiece
What is focal ratio?
Focal length of objective/objective aperture
What are the defects with using our eyes as telescopes?
•very small aperture(diameter of lens)
•cannot integrate the signals received
How is energy recieved per unit time calculated?
Brightness/flux
What problem can compound lens solve?
Chromatic aberration
What are faults with compound lens?
Heavy and absorb a lot of light
What do newton replace refractors with?
Curved mirror
What was the issue with spherical mirrors?
Do not bring all the light to a single focus (spherical aberration)
How was spherical aberration solved?
Parabolic mirrors
What are all telescopes today?
Reflectors
What do modern day telescope designs permit?
Cassegrain focus design allows more compact telescopes
Why can large telescopes produce sharper images?
Diffraction
What is resolution limited by?
The atmosphere
What are ways to beat the atmosphere?
Adaptive optics and putting telescope above atmosphere
What is adaptive optics?
Moving telescope to follow the star then the seeing disk would be reduced to a point
What is seeing?
The blurring of the image of a star due to turbulence in the earth’s atmosphere
How can we improve resolution?
Using multiple telescopes together
What are interferometers limited by?
The distance between the telescopes rather than the individual telescopes aperture
What rays must be observed from space?
Uv, xray, gamma
