I found this on this site in the physics rsources thing, sounds pretty good to me:
Key discoveries in imaging and measurement of celestial bodies typically follow the introduction of improved technologies. Tyhco Brahe’s large metal and wooden quadrants and scales allowed an enormous improvement in the measurements of the position of celestial bodies. Kepler then used Brahe’s measurements to calculate that the orbit of Mars was elliptical, undermining the accepted belief in circular orbits.
The invention of photography in the 19th century allowed lengthy, integrated exposures that produced a permanent image that could be measured and analyzed. It allowed stars to be accurately compared over time, this allowed time-varying phenomenon such as variable stars to be studied. Measurements of plates allowed magnitudes of objects to be determined, and faint objects such as galaxies to be determined. The development of the spectrograph led to the discovery of helium in the sun before it was found on Earth.
Hubble combined long-exposure photographic plates with spectral observations to discover that galaxies were separate from the Milky Way and that the Universe is expanding. These discoveries had profound social and philosophical implications.
More recently, developments in electronics have allowed astronomers to observe wavelengths other than visible light. The advent of computers and space based telescope has allowed them to detect and image objects such as nebulae and galaxies across the electromagnetic spectrum.
By linking CCDs to optical fiber feeds, spectroscopic surveys such as 2dF have allowed astronomers to observe about 250 000 galaxies and construct 3-d maps of the universe, a vital development to test various cosmological theories.
