Carla, Monday 17 March 2008
On first arriving in Antarctica it was a bit strange to wrap our minds around the 24 hours of sunlight being experienced here. After three months of 24-hour sun, some of the summer staff were dreading to go back to the real world of the dark nights. Others were seriously itching for a starry night! We sat in the bar getting to know these new people, sipping our drinks while gazing out at the ice and mountains. The hours ticked by but the sun remained.
It was just so bizarre to go to bed at midnight with the sun still blazing through the windows.
Well, the light is fading just as we’ve become accustomed to it, and we’ve begun to see some pretty amazing skies during the evening. We are now headed towards Vernal or Spring Equinox, which occurs on March 21 at noon, when the sun is directly overhead at the equator. At this time the sun sheds an equal amount of light and darkness over the entire globe, giving everybody from Antarctica to the Arctic 12 hours each of sunlight and darkness. From this time onwards night-time in Antarctica will increase by 20 minutes each day, as the sun rises ten minutes later and sets ten minutes earlier.
Nearing the end of June we enter the time known as “polar nights” or, 24 hours of darkness, while simultaneously the Arctic experiences “polar days”, or 24 hours of sunlight. So just how does this happen?
Well, we all know that the Earth is tilted on its axis, 23.5° to be exact. It’s this tilt, along with the Earth’s rotation around the sun that gives us our seasons, and the length of our days.
The figure below shows how Antarctica enters darkness as the Arctic tips towards the sun.
If the Earth were straight up and down, we would have no seasons, get no summer holidays, and wouldn’t enjoy things like spring blossoms, colourful autumn leaves and snow shovelling! This tilt and rotation send Antarctica into complete 24 hour darkness for three months on June 21. This is called Summer Solstice, the first day of summer in the Northern Hemisphere, the longest day of the year and my sister’s birthday – Erin, I hope you think of me and eat something DARK and chocolatey!