The Austral Moon of Evening


Waxing Moon in Evening Twilight Colours

From the southern hemisphere the Moon appears “upside-down” and higher each night in the northern sky as it waxes from crescent to Full.

These are scenes from the last week as the Moon rose higher into the evening sky as seen from Australia.

A northerner familiar with the sky would look at these and think these are images of the waning Moon at dawn in the eastern sky.

Waxing Crescent Moon at Cape Conran
The “upside-down” waxing crescent Moon in the evening sky from Victoria, Australia, at Cape Conran, West Cape area, on the Gippsland Coast, at latitude 37° South. Earthshine lights the dark side of the Moon. This was March 31, 2017. The Moon lights a glitter path on the water. This is a single 1.3-second exposure at f/2 with the 85mm Rokinon lens, and Canon 5D MkII at ISO 400.

But no, these are of the waxing Moon (the phases from New to Full) with the Moon in the evening sky.

From the southern hemisphere the ecliptic – the path of the planets – and the path of the Moon arcs across the northern sky. So as the Moon waxes from New to Full phase it appears to the right of the Sun, which still sets in the west. The world still spins the same way down under!

So the Moon appears upside down and with the crescent phase the “wrong” way for us northerners.

Panorama of the Waxing Moon at Sunset at Welshpool Harbour
A 240° panorama from 16 segments.

This panorama taken April 4 sweeps from northwest to southeast, but looks north at centre, to capture the scene at sunset of the waxing 8-day gibbous Moon in the northern sky as seen from the southern hemisphere.

The angle between the Sun and Moon is just over 90°, shown here by the angle between the right-angle arms of the wharf, pointed to the west at left, to the north at centre, and to the east at right.

The Sun has set just north of west, while the Moon sits 13° east of due north. The Earth’s shadow rises as the blue arc at far right to the east opposite the Sun.

Philip Island Sunset and Waxing Moon Panorama
A 240° panorama from 15 segments.

The next night, April 5, I shot this panorama from Philip Island south of Melbourne. Again, it shows the waxing gibbous Moon in the north far to the right of the setting Sun in the west (at left).

Getting used to the motion of the Sun and Moon across the northern sky, and the Moon appearing on the other side of the Sun than we are used to, is one of the challenges of getting to know the southern sky.

Things just don’t appear where nor move as you expect them to. But that’s one of the great delights of southern star gazing.

— Alan, April 8, 2017 / © 2017 Alan Dyer / www.amazingsky.com

 

Moon of the Austral Sky


Sunset and Waxing Moon over AAT Dome

When visiting southern latitudes nothing disorients a northern hemisphere astronomer more than seeing our familiar Moon turned “the wrong way!”

With the Moon now dominating the night sky, my photo attention in Australia turns to it as my celestial subject.

It’s wonderful to see the Moon as a crescent phase in the evening sky, but now flipped around so it looks like the Moon we see from home up north when it is a waning crescent in the morning.

However, the lead image above actually shows the waxing crescent in the evening. It shines above the volcanic hills near Warrumbungles National Park, with the added silhouette of the dome of the Australian Astronomical Telescope, the largest optical telescope in Australia.

After a lifetime of seeing the Moon in its northerly orientation, seeing the austral Moon throws off your sense of time and direction. Are we looking west in the evening? Or east in the morning? The Moon just doesn’t make sense!

Full Moon with Glitter Path
This is a two-exposure composite: a long exposure for the sky and ocean, and a short exposure for the disk of the Moon itself, to preserve some detail in the disk, specifically the mare areas to show the face of the Moon and not an overexposed white disk. Both with the 135mm telephoto and Canon 6D, from Woolgoolga, NSW.

Then there’s the Full Moon. It rises in the east, as does the Sun. But like the Sun, the “down under Moon” moves from right to left across the northern, not southern sky. And the familiar “Man in the Moon” figure is upside down, as seen above.

The photo above is from Friday night, and shows the Full Moon rising in the northeast over the Pacific Ocean.

Golden Glitter Path of the Moon
The apogee Full Moon of April 22, 2016 rising over the Pacific Ocean and lighting the waters with a golden glitter path of reflected moonlight. I shot this from the Woolgoolga Headlands viewpoint, with the 135mm telephoto and Canon 6D. This is a high dynamic range stack of 5 exposures to compress the range in brightness. Even so, the Moon itself is still overexposed.

This “HDR” image above from earlier in the evening captures the golden glitter path of moonlight on the ocean waves. I photographed these Full Moon scenes from the Headlands viewpoint at Woolgoolga, a great spot for panoramic seascapes.

The Full Moon this night was the apogee Full Moon of 2016 – the smallest and most distant Full Moon of the year, the opposite of a “supermoon.”

Gibbous Moon Over Upper Ebor Falls
This is a high dynamic range stack of 7 exposures to preserve the range in brightness between the bright sky and Moon, and the dark ground in the dim twilight.

Earlier in the week I was inland, high on the New England Tablelands in New South Wales. This image shows the waxing gibbous Moon in the evening twilight over Ebor Falls on the Guy Fawkes River, one of the few waterfalls on the famed Waterfall Way in New Soith Wales that has water flowing year round.

— Alan, April 24, 2016 / © 2016 Alan Dyer / www.amazingsky.com

 

Time and Tide … and the Pull of the Moon


Sunset at Point Prim Lighthouse, near Digby, Nova Scotia on the Fundy side of the peninsula, with a waxing crescent Moon in the western twilight sky. The dark rocks are basaltic volcanic rocks from the late Triassic formed as part of the rifting that split Gondwonaland into the Americas and Europe and Africa. The Lighthouse is the fourth in a succession of lighthouses built at Point Prim starting in 1804. It was automated in 1984. This is a panorama created from 9 segments taken with the 16-35mm lens at 35mm and Canon 6D. Stitched in Photoshop.

Nothing demonstrates the power of the sky to affect the Earth better than the daily ebb and flow of the tides.

For a few days earlier this week I was fortunate to visit Nova Scotia, to speak at the annual Nova East Star Party.

A scene at the Nova East Star Party near Windsor, Nova Scotia, in August 2015, showing laser pointer in use under a clear starry sky.
A scene at the Nova East Star Party near Windsor, Nova Scotia, in August 2015.
I took advantage of my visit to Canada’s east coast to shoot time-lapses of one of nature’s most amazing phenomena, the daily pulse of the tides.

The coastal regions around the Bay of Fundy, particularly on the Nova Scotia shore, and around the Minas Basin, experience the highest tides in the world. The range can be as much as 16 metres. Only remote Leaf Basin on Ungava Bay in northern Québec matches the Minas Basin for tidal range.

The reason is not, as is sometimes stated, the funnel shape of the Bay of Fundy, but rather its length. It takes about 12 hours and 25 minutes for an ocean wave to traverse the length of the Bay, equal to the time between successive high tides. This creates a resonance, with the incoming and outgoing waves building upon each other and increasing the height of the twice-a-day tides.

The amount of water moving back and forth is mind-boggling: some 9 to 16 billion tonnes of water flows daily into and out of the Minas Basin alone, enough to tilt the land.

For the time-lapse videos I shot at two locations:

  • Evangeline Beach on Minas Basin, with vast tidal flats that are engulfed twice a day.
  • And Halls Harbour on the Fundy shore, a great spot for watching boats go from grounded to afloat in just an hour or so.


I timed my arrival at both sites to be there near lowest tide and shoot for about 3 hours as the tide came in, then stop shooting at about high tide.

Luckily, high tide on both days was about 3 p.m. making for convenient shoots on a summer afternoon. Being just after New Moon, the tides were near their highest.

Earth experiences two tides a day, at an interval of about 12 hours and 25 minutes, with the extra 25 minutes coming from the motion of the Moon around the Earth during that half-day interval. It takes another 25 minutes for us to line up with the Moon again.

But why two tides a day? If the Moon pulls at our water why isn’t there just one high tide, when the Moon is highest in our sky?

The Moon doesn’t pull on just the water. It pulls on everything.

And it isn’t the Moon’s gravity per se that raises the tides, it is the difference in the strength of that gravitational pull across an object.

The side of the Earth closest to the Moon feels the strongest pull, raising the tides on the side facing the Moon. But the Earth itself is also pulled toward the Moon, but to a lesser extent because the centre of our planet lies farther from the Moon.

In effect, the Moon pulls the Earth away from the water on the far side of the Earth, the side away from the Moon. This raises a bulge of water on the other side of our planet, the side that feels the least gravitational pull from the Moon because it is farthest from the Moon.

So as Earth rotates we pass through two tidal bulges, one facing the Moon and one facing away from the Moon.

Newton's Apple Tree

It wasn’t until Isaac Newton came along in the mid-17th century that we had an explanation for and an ability to predict the tides accurately. Even Galileo got it wrong. It was Newton’s mathematical explanation of how gravity fell off with increasing distance that led to an accurate theory of the tides. See Wikipedia for much more detail.

The tree above is a direct descendent of the famous “Newton’s Apple” tree that inspired his theory of universal gravitation. It is an apple tree on the picturesque grounds of Acadia University in Wolfville, Nova Scotia, and was grown from a cutting from the famous apple tree at Woolsthorpe Manor where Newton grew up and took refuge during the outbreak of plague in the cities.

Newton's Apple #1

It was during this retreat that, story has it – a story told by Newton himself – that an apple falling on his head inspired him to wonder if the same force that was causing the apple to fall was also keeping the Moon in perpetual orbit around the Earth.

Annapolis Tidal Generating Station

Today, we can turn the pull of the Moon into power, as here at Annapolis Royal where Nova Scotia Power operates the only tidal power station in North America, driven by water pouring into and out of the Annapolis River. The pull of the Moon here generates 20 megawatts of electricity.

New submerged turbines are now being tested in the Minas Basin, using a variety of technologies. A previous underwater turbine at the same site was ripped to pieces by the force of the water. Harnessing the tides is not so easy.

Tide watchers take note: The Full “supermoon” of September 27 (when there is also a total eclipse of the Moon) will be especially close. Favourable geometry will raise the highest tides in 18 years in the two days that follow the Full Moon.

The Moon truly has the power to move the waters and the Earth.

Many thanks to my host Dr. Roy Bishop for the tidal tour and elucidation. Click here to download an article of his about the tides. 

– Alan, August 21, 2015 / © 2015 Alan Dyer / www.amazingsky.com

The Pull of the Moon


Moonrise at Woolgoolga, Australia #2

The Full Moon rises over the Pacific Ocean, exerting its pull on the ocean tides.

This was the scene last night, Monday, March 17, 2014 from the headlands at Woolgoolga, New South Wales, Australia. The views overlook the Pacific Ocean with the Full Moon rising. If the Moon looks a little odd, it’s because I took these images from “down under,” where the Moon appears  upside down compared to what we northerners are familiar with.

However, no matter your hemisphere, the Moon exerts a tidal pull on the globe, which manifests itself most obviously as the twice-daily rise and fall of the ocean tides at shorelines like this. When I took these shots at moonrise, the tide was just past its minimum and was beginning to come in again, for a peak later that night with the Moon high in the north.

Moonrise at Woolgoolga, Australia #1

This image was from a few minutes earlier, with the Moon having just risen and looking a little more pale against the darkening twilight of the eastern horizon.

I’m in Australia for the next few weeks, to shoot lots of images of the southern autumn sky, skies permitting.

– Alan, March 18, 2014 / © 2014 Alan Dyer

The Green Flash – At Last!


The Green Flash (Nov 15, 2013) from Barbados

At last, I enjoyed a successful attempt to capture the elusive green flash.

During three weeks at sea attempts almost every evening from the ship to sight the green flash always failed, as the Sun set behind low horizon cloud.

But this night, the Sun set into the ocean with a clear horizon. My location was a small public oceanside walkway on Bay Street near Bridgetown, Barbados. It was a great spot to watch the sunset, though our main purpose for stopping there was to pick up some fried chicken at the KFC just steps away!

But the imminent sunset under ideal conditions made it worthwhile sticking around to see if we (I was with two friends from Alberta) could sight the green flash.

We did! I shot a rapid fire sequence – the image above is one frame of many catching the last bit of the Sun remaining above the horizon and turning green.

The infamous green flash is a refraction effect caused by the atmosphere separating out the green light and lifting it higher so it’s the last thing you see as the Sun sets. Conditions aren’t always amenable to seeing the green flash – you need a clear horizon and you also need the atmosphere structured with warm layers near the sea creating a mirage effect.

For more details on the technical explanations see Andrew Young’s page at http://aty.sdsu.edu/ 

… and Les Cowley’s page at http://www.atoptics.co.uk/atoptics/gf1.htm 

Andrew Young has a nice simulation at http://aty.sdsu.edu/explain/simulations/inf-mir/inf-mirSS4GF.html

Sunset from Barbados (Nov 15, 2013)

This was the view moments before, with the lower edge of the setting Sun distorted by atmospheric refraction, a sign that you might see a green flash as the upper edge disappears.

Sunset & Sailing Boat from Barbados

I shot this image a few minutes earlier as a photogenic sailboat drifted into the scene. Red sails in the sunset!

I’m nearing the end of my stay in Barbados and my 4 weeks away from home. There are heavy snowfall warnings out for southern Alberta this weekend so I’m not anxious to return! But winter will be waiting for me next week.

– Alan, November 16, 2013 / © 2013 Alan Dyer

 

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