In the Southern Hemisphere, 21 June is the shortest day of the year. Image Credit: flagstaffotos.com.au / Wikimedia / CC BY-NC

Happy winter solstice!

  • BY Shannon Verhagen |
  • June 20, 2017

The winter solstice is upon us again – but what exactly is it, and why does it happen?

TODAY IS THE shortest day of the year (the winter solstice) for the Southern Hemisphere – an astronomical phenomenon that occurs each year in June as the Earth orbits the Sun.

But why is it the shortest day of the year?

“It all comes down to the fact that the Earth is tilted at about 23 degrees,” explains Geraint Lewis, Professor of Astrophysics at the Sydney Institute for Astronomy.

“So what happens is that orientation in space is fixed, and at some point the top of the Earth is closer to the Sun than the bottom.

“We are at the point where the Southern Hemisphere is further from the Sun.”

Earth Sun NASA

The solstices relate to the tilt of the Earth. The Southern Hemisphere is currently tilted away from the Sun. (Image: NASA)

Each year the solstice falls between 20-22 June for the Southern Hemisphere, while the summer solstice – the longest day of the year – occurs between 20-22 December.

 “The word 'solstice' means 'Sun still',” says Fred Watson, astronomer at the Australian Astronomy Observatory.

“The Sun stands still in the sense that it’s northern and southern journey stops.”

RELATED: Best winter escapes in Australia

From today, the days will get longer as the Earth continues to orbit, the Southern Hemisphere getting closer to the Sun each day as it approaches the December summer solstice.

The shortest day of the year is a perfect time to catch the late sunrise and early sunset. Here are the sunset times around Australia today:

Sydney, NSW 

16:54

Melbourne, VIC

17:08

Adelaide, SA

17:12

Perth, WA

17:20

Hobart, TAS

16:43

Brisbane, QLD

16:02

Canberra, ACT

16:58

Darwin, NT

18:30

Alice Springs, NT

17:56

Broome, WA

17:24