For most of us, the winter solstice marks the shortest day of the year and means the journey towards summer has begun.
But for astrophysicist Professor Tim Bedding it's an opportunity to dispel myths about the seasons and the earth's orbit.
The winter solstice occurs Thursday at 8.07pm (AEST) when the earth's tilt will be 23.4 degrees.
It's the exact time when the southern hemisphere or pole is tilted directly away from the sun and the north towards it.
Prof Bedding said although humans have historically used the winter and summer solstices as time markers for seasonal agricultural activities, many people don't understand that the earth's tilt is why we have solstices and seasons.
"The most common misconception people have is that summer and winter happen because the earth is closer in summer and further in winter," he told AAP on Thursday.
"You'll still find well-educated people who think that."
But Prof Bedding said the earth's journey around the sun is almost circular and the seasons actually occur because the earth's tilt causes the northern and southern hemispheres to receive varying exposure to the sun during its year-long orbit.
He said although we get sunlight all year round in Australia, when the winter solstice occurs later today the southern hemisphere will be directly tilted away from the sun.
"We get sunlight but we don't get it for as long and when it does get to us it's shining more at an angle, so the sun is lower in the sky and the heat from the sun is spread over a bigger area," he said.
It's why winter is colder and the days shorter than in summer, when the tilt creates longer and warmer days.
Prof Bedding pointed to Stonehenge in southern England and more locally, the Wurdi Youang rock formation in Victoria, which was used by indigenous Australians to mark solstices more than 25,000 years ago.
"They wouldn't have realised the earth was tilted on its axis, they probably didn't realise the earth orbited around the sun either," he said.
"But they knew something was changing and they could see it."
Celebrations to mark the winter solstice carry on to this day.
From Tasmania's Dark Mofo festival to a -3C nude swim in Canberra's Lake Burley Griffin, Australians are embracing the shortest day.
But the finest example of midwinter madness is surely Australia's Antarctic team who braved -22C temperatures and plunges into the icy ocean to continue a winter solstice tradition that began with early explorers, such as Sir Douglas Mawson.
Their midwinter celebrations at Australia's three Antarctic research stations and sub-Antarctic Macquarie Island also include a feast, exchange of handmade gifts, midwinter play and messages from home.
