Polar Passport

Ready To Go

If you've been following the ship online, you'll know that the Aurora Australis has been at Davis a couple of days now, anchored offshore in the bay.

The photo shows Aurora Australis loading cargo, with Davis in the foreground. It's been a busy time, with two barges and some smaller boats ferrying back and forth between the ship and the station bringing supplies needed for the winter, returning cargo to Australia, and removing a lot of waste. We expect to leave tomorrow.

It's a time of mixed emotions - those of us who are going home are sad to leave Antarctica, but also tired after a summer of hard work and eager to get back. For the winterers, this is the last ship they will see for eight months.

The weather has been beautiful - calm sunny days and clear nights with some large pale green auroras. The lakes behind the base already have a thick layer of ice, strong enough to walk on, and the calm sea also freezes a thin skin which breaks if the wind starts to blow a little.

People are spending a lot of time outside, soaking in the scenery. After a few months, we're used to having icebergs in our backyard and glaciers next door, but we know that we'll miss them badly when we get home.

Homeward bound,

Dan

A Lunar Eclipse

Saturday night is always a bit special at Davis - the chef makes a special meal, we lay the tables with tablecloths, cutlery and glasses, and cover the windows to darken the dining room. Candles are lit, people dress neatly, and there's a sense of occasion.

Last night was extra special - it is probably the last Saturday night before the ship arrives to take us home. So the meal was extraordinary, and there were a few speeches recognising the work accomplished by those of us who came just for the summer, and the challenges ahead for the smaller group staying on for the whole winter. That sounds a bit too serious - it was mainly great fun, a celebration of the nice station community we have become over the past months.

After the lavish dinner (I think we will be eating leftovers for a week!), the station band played in the lounge and the party got steadily louder. When it got too loud for me I left, and when the heavy insulated door clunked shut behind me, the night's entertainment really started to get good.

After a calm sunny day and a glowing sunset, the night was gorgeous: calm, clear and cold, -8°C already as I left the building, and getting colder. In the west, the constellation of Orion, lying on his side, was setting over the horizon where distant icebergs lay in the moonlight. In the east Scorpio was already clear, and the Southern Cross was almost directly overhead. The full Moon made the sky too bright to see all the stars, but the scatter of the Milky Way was a clear band.

I knew that there would be an eclipse of the Moon later in the night, so I set my alarm clock and got a couple of hours sleep. At 3:00 am I took my sleeping bag and walked a short distance to the edge of the station, where I had a view over the bay.

The eclipse started at 3:18, but the first stage (the penumbral phase, when the Moon is in half-shadow) was barely noticeable. Even without that, it was wonderful to be there: although it was the middle of the night, elephant seals were bellowing and scrapping on the beach, and somewhere on the rocks below me there was a group of moulting penguins who gave an occasional squawk in the darkness. By now Orion had set, and his dog, with Sirius, the brightest star in the sky as his eye, was running full tilt at the horizon. Between Sirius and the Moon, a band of pale green aurora waved for a few minutes and faded away again.

I dozed off in my sleeping bag, but at 4:30 my alarm peeped to announce the next phase of the eclipse, when the Moon enters the umbra, or full shadow of the Earth. The dark circle spread across the face of the Moon, and as the sunlit area of moon got smaller over the next hour, the dimming was obvious - the reflection in the rippling waters of the bay below me vanished, and the Moon's shadowed area showed a red glow, caused by sunlight refracting through the Earth's atmosphere.

Eventually the entire face of the Moon was in shadow, which is normally the best time to see the red glow, but at Davis it was now almost dawn. The sky was getting lighter as the Sun approached behind me, and as the eclipsed Moon sank towards the row of icebergs on the horizon it simply faded into the background and vanished. I'll be watching this evening to see it rise again, now slightly smaller than full and beginning to wane.

With the eclipse over, I watched the dawn light turn the icebergs from distant white shapes into crisp three dimensional forms. The first rays of the Sun cast shadows from the icy cliffs and crenellations, and made the rocky hills and islands glow orange. I emerged from my sleeping bag and returned to my warm bed for a few hours more sleep.

Isn't our solar system a great place to live?!

Dan

Looking Up

As the summer is ending, the Sun is now below the horizon for about eight hours per day. I can hardly believe that just two weeks ago, when I was in the Grove Mountains, the sun just touched the horizon, and we had 24 hour daylight. But that was 500 km further south, and the seasons move quickly!

So we have a real dark night again now, and when the sky is clear the stars are wonderful. We've even seen some faint auroras. But recently I was thrilled to see the Davis LIDAR working.

LIDAR stands for "Light Detection and Ranging", which is the same as RADAR, except that it uses light instead of radio waves. That means it can look for different things: radar can detect bigger heavier objects, like planes, or rain; lidar can study the air itself, how cold it is and how much wind there is.

It is particularly interesting to measure the temperature of the atmosphere high above us, because that is where we expect to see some of the effects of global climate change. As greenhouse gases make the lower atmosphere warmer, they also make the higher atmosphere colder. So the lidar will help scientists test their predictions of climate change. You can read more about it on the AAD website.

The lidar is one of many interesting science studies being done at Davis, but the reason I wanted to write about it is that it looks so cool!

Photo by Mark Tell, courtesy AAD.

When it's running, a bright green laser points straight up into the sky. It looks like a real light sabre, or an enormous beanstalk. And it goes up and up and up... it makes measurements up to almost 100 km altitude, but when you look up, it just disappears into the distance, where the stars are.

Happy stargazing,

Dan