Observatory Locations13.23 - Know that only optical and radio telescopes should be located at sea level on the Earth’s surface
13.31 - Understand why telescopes operating outside the optical and radio ‘windows’ need to be sited above the Earth’s atmosphere
There are 4 main types of astronomical observatories:
For our purposes we will only look at ground and space observatories. Now this bit is awkward... the spec says about locating optical and radio telescopes at sea level. This isn't correct. Soz. We're going to assume they mean ground.
From Earth we can study the optical and radio wavelengths farily easily. We can see a little infrared in precision observatories and a miniscule fraction of ultraviolet - this is what gives us sunburn. We cannot study x-ray or gamma ray astronomy from the surface as Earth protects is from these harmful emissions. For those we need to study from above Earth's atmosphere.
The drawbacks of Earth's atmosphere for astronomy mean that locations of observatories have to be carefully selected:
- Frequently, larger observatories are built in remote locations far removed from light pollution.
- They are also built on high mountains so there is less atmosphere to obscure viewing.
- Located in areas that have good, dry weather and fewer clouds, so typically nearer the tropics or Equator.
- Dry weather is especially important for infrared astronomy as water vapour in the atmosphere acts as an interference.
- Less infrared light penetrates to the surface so a higher location is better for those observations.
- Radio Telescopes are typically far away from cities and towns as microwaves from mobile phones and other transmitters interfere with signals
What are the factors that decide where an Observatory is to be built or positioned?