Further Physics - Observing the Universe - How Astronomers Work and Different Types of Telescope
How Astronomers Work Together
Astronomers have gathered evidence about the Universe using telescopes. As they try to gather more and more evidence from faint and distant sources, which have weaker radiation, the telescopes have had to become larger and more expensive. Astronomers use different types of telescope including radio, infra red, ground based and space based.
Radiation is diffracted by the aperture of a telescope. To produce a sharp image, the aperture must be much larger than the wavelength of the radiation. Large radio telescopes that detect weak radio wave radiations can be built, but because radio waves have a long wavelength they are affected by diffraction. This means that the image produced is not very sharp.
Light has a very short wavelength. Optical telescopes have a much larger aperture than the light's wavelength. Therefore, the telescopes are able to produce a sharp image.
Ground-Based Optical Telesopes
The largest refracting optical telescope in the UK is sited at the Royal Observatory in Greenwich. However, it's aperture of 70cm seems tiny when compared to the largest optical telescopes in the world - the 10m aperture reflecting Keck Telescopes at the Mauna Kea observatories, Hawaii.
Hawaii has proven an ideal location for ground-based telescopes for several astronomical reasons:
- It's high altitude means that there is less atmosphere above it to absorb the light from distant objects.
- The lack of nearby cities mean that there is less pollution (light and air) to interfere with the received signal.
- Its equatorial location gives the best view of solar eclipses.
There are other things that must be considered when deciding where to build an observatory. For example: