Breakdown of Eru þær að ferðast til Ástralíu í dag?
vera
to be
þær
they (f)
að
to (infinitive marker)
í dag
today
Questions & Answers about Eru þær að ferðast til Ástralíu í dag?
Why is the pronoun þær used here instead of þeir or þau?
In Icelandic, the plural word for "they" changes depending on the gender of the people or things you are talking about. Þær is the feminine plural, meaning this sentence is specifically about a group of women. If it were a mixed-gender group, you would use the neuter þau, and for an all-male group, the masculine þeir.
The verb ferðast ends in -st. Is this a special conjugation for this sentence?
No, ferðast (to travel) belongs to a category called -st verbs (sometimes called middle voice verbs). These verbs always end in -st in all of their forms. In this sentence, it is actually in its dictionary form (infinitive) because it follows the particle að.
Why is Australia spelled Ástralíu here instead of Ástralía?
The preposition til (to) always forces the noun that follows it to take the genitive case. The basic, dictionary form of the country is Ástralía, but in the genitive case, this feminine noun drops the -a and takes an -u ending, becoming Ástralíu.
How does the sentence create the continuous "are traveling" meaning?