Australian Antarctic expeditioners are living in the twilight zone after the last sunset on the icy continent for weeks.
Yesterday, expeditioners at Davis research station farewelled the sun as it dipped below the horizon, not to rise again until July 10.
Davis research Station Leader, Simon Goninon, said the entire wintering team of 19 gathered to wave goodbye to the sun.
"It's incredible to think we won't see the sun or feel it's warmth for more than five weeks," Mr Goninon said.
"We will have about three hours of civil twilight a day, with the sun between 0-6 degrees below the horizon, so it's a bit like the dark side of the moon here right now."
Across at Mawson research station, the last sunrise will be on June 13 with two weeks before the sun reappears on June 29.
At Casey research station the expeditioners will be treated to about 2 hours of sunlight a day as the sun skims along the horizon.
Chief Medical Officer from the Australian Antarctic Division's Polar Medicine Unit, Dr Jeff Ayton, said the lack of sunlight in Antarctica in winter can interfere with circadian rhythms.
"Our bodies are made to work on a body clock and that is driven by light. If we have the absence of light, then we can get in some difficulties in synchronising our sleep/wake patterns," Dr Ayton said.
"The key thing is to ensure expeditioners maintain a routine of working, eating and sleeping during these long periods of darkness, to help maintain their circadian rhythm."
2019 sun graphs for Australian Antarctic research stations:
Mawson – theoretically no sunset from 14-29 June
Davis – theoretically no sunset from 3 June-10 July
Casey - two hours of sunlight a day until July
