Anyone who is not an Australian citizen, or a New Zealand citizen traveling on an NZ passport, needs a valid visa or Electronic Travel Authority (ETA) to enter Australia.
Visas are available from Australian visa offices, such as Australian Embassies, High Commissions and Consulates.
They are also available in ETA form from travel agents and airlines for holders of the following passports:
Andorra, Austria, Belgium, Brunei, Canada, Denmark, Finland, France, Germany, Greece, Hong Kong, Iceland, Ireland, Italy, Japan, Liechtenstein, Luxembourg, Malaysia, Malta, Monaco, Netherlands, Norway, Singapore, South Korea, Spain, Sweden, Switzerland, Taiwan, United Kingdom, and USA.
More information can be found at http://www.immi.gov.au/visitors/visas.htm
If you require a letter of invitation in order to obtain a visa please email profiler@physics.adelaide.edu.au giving your contact details, including a fax number.