WHY BUILD BIG TELESCOPES?
One reason to build big telescopes is the desire to collect many photons. Therefore, bigger telescopes can detect fainter signals because they act like bigger light buckets. Another reason for building telescopes relates to our desire to separate distant sources into distinct components, what we call resolution. Two distant objects will appear blurred together as a single object if our resolution is not adequate. Like eyeglasses or a pair of binoculars, a telescope allows the scientist to focus the light from a distant object to produce a sharper image. The smallest angle we can separate (or resolve) depends on the wavelength of the light (shorter wavelengths give better resolution) and the size of the telescope (bigger telescopes give better resolution). Optical telescopes on the ground do not have to be very big for the reason that the limitation on the resolving power is not the size of the telescope but the twinkling of the earth’s atmosphere which blurs the image. Although radio w
