It is a great coincidence that the apparent size of the Moon and of the Sun, as viewed from Earth, are almost exactly the same, and that the orbits of the Earth and the Moon are so aligned that the latter periodically can pass directly in front of the Sun, completely obscuring it in the middle of the day.

Partial eclipses of the Sun can be viewed from many places on the globe, and quite frequently. The last total eclipse was the last of the 20th Century and occurred on August 11, 1999. The March 2006 eclipse will be the first of the 21st Century.

But a total eclipse throws a very narrow shadow that traces a path across the Earth. One must be exactly below this "umbral" part of the shadow, which is just 130-190 km wide, to see the Sun fully covered. In the above picture you can see the umbral path of the March 2006 eclipse, which begins in Brazil and extends across the Atlantic, northern Africa, and central Asia where it ends at sunset in western Mongolia. The duration of totality is less than 2 minutes near the sunrise and sunset limits, but will be as long as 4 minutes and 7 seconds in Libya, at the moment of greatest eclipse.

We understand that very few of our readers will happen to live in places along the umbral path, and only a few more within driving distance of such places. Saharan Africa, Libya, Kazakhstan and Mongolia are difficult to reach, even for hardened travellers. But Turkey, and especially the holiday resort of Antalya, offer Europeans an excellent chance to see a total eclipse. That is where the author of this report is currently waiting for this once-in-a-lifetime spectacle.

Watching the total eclipse with Fritz

For those of you who have not made the trip to Turkey (or one of the other places) there are a number of alternatives. You can watch it on TV, or you can go to one of the live webcasts of the event. Or you can watch it with Fritz (versions 8 or 9) by logging into the Playchess server. Here are some instructions on how to go about it.

First of all you will want to optimise our globe settings. Log into the server and click on "Tools – Options".

In the dialog that appears click on "Globe Settings" and switch on the options as shown above. "Photo Globe" gives you the niceset picture. Make sure that the sun and moon will be displayed, i.e. that those options are switched on.

Now click on the "World" tab. This should give you a splendid view of the globe.

You may have to scroll back to see the entire globe. This is best done with the mouse wheel, but there are also buttons at the bottom of the window for that.

You may want to adjust the graphics to suit your hardware and graphics card accelerator. First of all try checking "Hires Texture" in the "Tools – Options" menu shown above (click on "Photo Globe"). You can also right-click the globe window and try switching to DirectX for optimum acceleration.

The next step, if you want to view the eclipse it totality you will need to switch your location to a place that falls under the umbral shadow. Select one from the NASA links given below, or follow us to Turkey, where the longest duration will be encountered. To do this click on "Edit – Edit User Data" and then click on the "Find coordinates" button.

In the dialog box that appears select a city that is near the umbral path. We have selected Ankara, Turkey, wich is not exactly under the main shadow, so we have to tweak the coordinates a little. The values are shown above.

By clicking around on the globe you can get a view of the sun and the moon, hovering near the earth. However, in order to get a view as seen from the earth press "S" or "M". This will produce a display of only the sun and the moon.

The above screen shots are what you can expect to see druing the March 2006 total eclipse. The first is a about twelve hours before totality. The second is one an hour or so earlier, and the third shows totality. Due to the static image sizes we are using for the sun and the moon (to make them more easily distinguishable in our globe display) the moon does not cover the entire sun, as it will do during the total eclipse. However the positions are accurate.

This is what a total eclipse looks like through binoculars [Photo Luc Viatour]

Totality occurs at 11:00h UTC (GMT) at the location we have entered . You can see how that translates to the time at your (real) location at the World Clock home page. Or you can simply log into the server occasionally to check the progress of moon and sun. Hard core computer users can even change their system date and time to watch the eclipse before or after it actually occurs.

Links

• NASA Eclipse home page
• Maps, times, circumstances of the Eclipse Path
• Umbral path in Southern Turkey