18
Why
do astronomers need large telescopes?
•Large telescopes can collect more light
–Can
detect fainter objects
–Have
more light for specialized analysis.
•Large telescopes can form more detailed
images
–Waves
spread out as they go through an opening.
•The
larger the opening, the less they spreads out.
•The
longer the wavelength the more they spread out
•Angle
of spread q µ l/D where D is Diameter of telescope
•Radio
telescopes have to be much bigger than visible ones
From our text: Horizons, by Seeds