Calls to change Australia's national day are mounting; with some saying the anniversary only honours the country's colonial history.

Thousands are expected to gather at celebrations across the Tasman today, commemorating the arrival of the first colonial British ships 230 years ago today.

But there are now moves to change the day, including from journalist Peter FitzSimons.

“The truth of Australia Day, I saw the poll the other day. 70% of my fellow Australians didn't know what happens on that day. For a significant body of our people, it's not a celebration of coming together, it was dispossession.”

And this year's Australian of the year is a ground-breaking scientist, Professor Michelle Simmons.