Shortest day of the year in Aotearoa tomorrow

Ōtautahi - The days are getting shorter and colder and afternoons spent soaking up the hot sun are long gone.

Tomorrow, June 21, Aotearoa will experience its shortest day and longest night of the year.

And Wednesday morning, the northern hemisphere will enjoy the summer solstice, the longest day and shortest night of the year.

What is the winter solstice? It comes down to the planet being a little wonky on its axis. Rather than rotating perfectly vertically, the globe is tilted at about 23 degrees.

This tilt is what gives us the four seasons: winter, spring, summer, and autumn.

On top of that, the earth doesn't travel around the sun in a perfect circle, but in a football-shaped ellipse.

During winter, our part of the Earth is tilted away from the Sun and therefore [the Sun] isn't above the horizon for as long every day," said Tim Bedding, an astronomer at the University of Sydney.

When is the winter solstice? The winter solstice marks the point at which the southern or northern hemisphere is tilted furthest away from the Sun.

In the southern hemisphere, this falls sometime between June 20-22 (June 21 this year), while in the northern hemisphere it usually occurs on either December 21 or 22.

The spring and autumn equinoxes occur when the sun appears directly above the equator, leading to days and nights being roughly equal in length.

Why doesn't it occur on the same day each year? While calendars help map out the year, they don't sync up perfectly with the sun's movements.

If the idea of spending most of the day in darkness is a downer, people should gaze up at the early morning sky.

If Kiwis look east, they will catch bright Venus, Mars, Jupiter, and possibly even Mercury appearing in a straight line in the sky just before dawn.

Also, according to tradition, the shortest day of the year is the time for gardeners to get their garlic cloves in the ground before the weather turns to custard.

Planting on June 21 means the garlic will be ready to harvest on the longest day - December 21.

The shortest day also coincides with the start of Puanga or Matariki celebrations which signify the start of the Maori new year and Friday June 24 marks the first ever Matariki national public holiday.