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
