Syzygy Sailing

post-dated:  this refers to events on July 11

(for background, see this previous post)

We observed the solar eclipse from the atoll Rangiroa in the Tuamotus. It occurred around 10 in the morning, which is why in the pictures below Karen and I both look like we just got out of bed (jon was up at dawn). Jon found these cheap dark glasses for safely looking at the sun, which is why we all look like we’re watching a cheesy 3D movie.

It was great to observe a solar eclipse, though it was admittedly less dramatic than I had hoped for. The viewing party lasted about 30 minutes, so it wasn’t as rapid as I had expected, either, which gave me some time to drink my coffee, wake up a bit more, and appreciate it.  We were just outside the area of the total solar eclipse; on Rangiroa we had something like a 93% totality, and it turns out that 7% of the sun is a hell of a lot brighter than you would expect.  At its darkest, it had a magnitude of illumination equivalent to the sunset.

Originally we had planned on being farther south, in the path of the total eclipse, but it turned out to be incompatible with all our other route-planning considerations.  I do not regret our choice.

As a photographer, I was most fascinated by the color temperature of the light.  At sunrise and sunset we describe the light as very “warm”: when the sun is very low in the sky, its light passes through much more of the atmosphere before it illuminates our surroundings; as a result more of the blue wavelengths are filtered out, leaving a more orange, or “warm”, illumination.

–ignorable aside:
The expression “color temperature” comes directly from physics: as an object is heated, it gives off radiation (this is called “blackbody radiation” fyi).  The temperature of the object determines the wavelength of radiation.  At room temperature, objects give off long wavelength radiation, in the infrared spectrum (which we cannot see, except with the help of special goggles anyway).  When the object gets hotter, say a couple thousand degrees, the wavelength of radiation becomes shorter, and it gives of visible light that we can see (think of a piece of metal glowing orange in a forge).  The hotter it gets, the shorter the wavelength. Orange light is longer wavelength, bluer light is shorter wavelength.  As a piece of metal heats up in the forge, it goes from orange towards blue in color.  So, strictly speaking, blue is hotter, orange is cooler.  However, photographers got it backwards and refer to orange light as warmer and bluer light as cooler; admittedly this seems more intuitive.  Since it is rare to find a photographer who pays any attention to physics, we’ll have to forgive them the mistake.
–end of ignorable aside.

During the eclipse the sun was high in the sky, and so even though the amount of light felt like a sunset, the illumination it provided had the color temperature of the mid-day sun–far “bluer” than we observe at sunset.   In fact, it felt exactly like moonlight–this makes sense because moonlight itself is only reflected sunlight.

So if you want to understand what it was like, imagine a sunset with moonlight.

Get this: Syzygy is going to experience a syzygy.

A ‘syzygy’ is an astronomical event in which three or more celestial bodies are perfectly aligned.  A solar eclipse–in which the moon blocks out the sun and shadows the earth–is an example of a syzygy.

There is going to be a total solar eclipse in the south pacific on July 11th of this year.

Solar eclipses come in two flavors, partial and total: during a partial solar eclipse, only a portion of the sun is blocked.  The total solar eclipse is the jackpot of all syzygy.  It is an extremely rare event, and it is only visible from a very tiny, quickly moving area on the earth for only a very few minutes (on this website, the little black dot illustrates the location of the totality).   The total solar eclipse is dramatic, with a full-on biblical feel to it: we’re talking about the moon completely blocking out the sun in the middle of the day, complete darkness, stars in the middle of the day.

Even fewer people will be able to view the total eclipse this july 11th because it barely touches land.  The atolls of Hao and Amanu in the Tuamotu Archipelago are on the short list (nasa doesn’t list them on their website because they are nearly uninhabited, nearly impossible to reach, and, being coral atolls, may not even be considered “land”).

We are planning to be there; we intend to treat Syzygy to a syzygy.  If that isn’t appropriate, right!?

When I learned of the total solar eclipse, I made a list of all the atolls that were in the path of the totality–we’re going for the real deal here–no partial eclipse for this party.  I used this nasa site to determine the precise track of the eclipse, and the time and duration of totality.  The list has 19 names on it.  Of those 19 atolls, it looks like only two (maybe a few more–more research is necessary) have a pass through which we can enter with our boat.  Hao is the current top contender.

This is the atoll “Hao”:

If this is your first glimpse of a coral atoll, you may be reacting with some of the same incredulousness that I did less than a year ago, when I went on google earth to see what we were headed for in the south pacific.  An atoll is an island that consists of a coral reef surrounding a lagoon.  This thing was once a piece of land sticking up out of the ocean; then a coral reef formed around the land; then the land sank below the surface.  The Tuamotu Archipelago consists entirely of atolls (78 of them).  No land, all coral, all rings like this, with lagoons in the center.  Some of them have “passes”–a place to slip through the reef, into the lagoon.  The rest have no pass, i.e. no way to get in, and thus are inaccessible to us.

On the aerial photo of Hao, you can just make out the pass at the very top of the island.  It is less than 300 yards wide–imagine trying to take that during a 20 knot current.  Here is a closer view (don’t worry, we’re not using this for navigation):

The Tuamotus are widely regarded to pose the most dangerous and difficult navigation in the world.  The water rushing into and out of the lagoon can cause 20 knot currents–it is crucial to precisely time your entry and exit during the narrow window of slack water between tides.  Once you enter the lagoon, you must navigate an obstacle course of “coral heads”–mounds of razor sharp rock hard coral that rise to within feet of the surface.  Some lagoons are blessedly free of the coral heads; others have hundreds of them so densely packed that it is impossible to cross the lagoon.  Compounding the navigational hazard, most of these atolls rise no more than a few feet off the horizon, making it frighteningly easy to accidentally run into them.  There are a number of these atolls that are completely submerged, with no visible land, lurking just under the water–you couldn’t have designed a better booby trap for a sailboat.

According to Nasa, if we end up just off the beach of the town of Otepa on the atoll Hao, we will experience 3 minutes and 30 seconds of total eclipse, starting at 18:41 UTC (which will be 8:41 AM for us, 5:41 pm on the west coast, 2:41 pm on the east coast).