by Knut Jørgen Røed Ødegaard and Unni Fuskeland
During an eclipse, a lot of strange phenomena can be experienced.
Here you can find out more about them, and how to create the phenomena.
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Beneath foliage, hundreds or thousands of partial eclipsed
Suns can be seen during an eclipse. The picure was taken
August 11. in Austria when 70% of the Sun was behind the Moon.
Photo: Oddleiv Skilbrei |
SUNSPOTS
If the weather is OK, we will be able to see sunspots, which are dark spots on
the Sun. The spots look dark because they are cooler than the rest of
the surface of the Sun. They are about 4500 degrees Celsius while the
temperature is
6000 degrees elsewhere. The spots are due to extremely powerful
magnetic fields that are many, many times stronger than on Earth.
Even the spots that do not appear so large in a telescope are
larger than the Earth in size. The Sun is huge!.
The amount of sunspots varies with a period of about 11 years. This
year it is a lot of spots, a so-called sunspot maximum.
The magnetic fields that makes the spots also causes a lot of powerful
outbursts on the Sun. These kind of outbursts are the origin of Auroras.
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From time to time there are many large and small sunspots
on the solar disc. During the eclipse we can experience
these, look at the page on how to observe.
Photo: SOHO/ESA/NASA
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REFLECTIONS OF THE SUN BENEATH TREES
Strange half-moon shaped reflections of the Sun arises under foliage.
You can see this if you find a suitable place with deciduous trees.
It is nice if the leaves are in medium size and the trees are tight
so that only some of the light gets through. The ground must be in such
a way that the reflections are visible.
Light asphalt, bricks, tables etc.are ideal.
Notice how the reflections changes when the Sun is getting more eclipsed,
and when the Moon pulls away.
SILVER-LIKE LIGHT
When the eclipse is above about 50%, the light is getting more soft and
silver-like in colour. This is because the direct, intense light from
the solar disc becomes weaker and makes the light from the solar corona
more noticable.
The sunlight comes from the visible surface of the Sun which is barely
6000 degrees Celsius. This layer is called the photosphere. Outside
the photosphere there are layers of the atmosphere with much lower density.
Innermost is the chromosphere which is cooler than the photosphere.
At the top of the chromosphere the temperature rises fast and in the large
layer that surrounds the chromosphere, the corona, the temperature is over
one billion degrees. One should believe that gas with a temperature
over one billion degrees is radiating heavily. But the corona is not!
The reason is that the gas in the corona has very low density.
Seen from the Earth, the light from the corona is much weaker than from the
surface of the Sun.
It is only during total eclipses that we can see the corona from the
ground. But during partial eclipses, parts of the sunlight is shaded
so that the super-hot, silver-like light of the corona is visible.
During the May 31. eclipse a large area of the Sun will be covered and this
is expected to be noticeable. At the same time the light is subdued and it will
become darker.
TRY TO SEE VENUS!
When the eclipse is at its maximum, the sunlight is softened.
We can then try to see the planet Venus which normally drowns in the daylight.
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When the eclipse is at its maximum, the sunlight is softened.
We can then try to see the planet Venus which normally drowns in the daylight.
This is how the sky will appear when the eclipse is at its maximum at 05:40
Saturday May 31. Venus is to the right of the Sun.
Mercury is probably not bright enough for us to see it with our eyes.
Illustration: Institute of Theoretical Astrophysics, University of Oslo
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PICTURES TAKEN DURING THE TOTAL ECLIPSE IN SOUTH OF AFRICA, 2001
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Early in the partial phase, the eclipse has no effects to the eye
(except when looking with eclipse glasses at the solar disc).
But then, more and more interesting and fascinating phenomena
begin to show. The picture shows how the spaces in the foliage
makes reflections of a lot of partially eclipsed Suns. Instead of the
ordinary diffuse spots of light, Suns-arcs are showing on the ground.
Here the eclipse is here well over 50%.
Photo: Herman Ranes |
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When the eclipse is about 90-95% one really notices that it is less light.
The shadows are becoming sharp because the sunlight now comes from a small
point in the sky. The photographer has taken a picture of his own shadow.
Photo: Herman Ranes |
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When the eclipse is waning, the thin Sun-arcs point in the opposite directions
than before the maximum eclipse.
Photo: Herman Ranes |
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CONTACT PERSON:
Knut Jørgen Røed Ødegaard
Project leader
Institute of Theoretical Astrophysics
P.O.Box 1029 Blindern
N-0315 Oslo
Norway
Phone: +47 22 85 75 22 (Institute of Theoretical Astrophysics)
+47 992 77 172 (mobile phone)
+47 613 11 359 (private, weekend)
Email: knutjo@astro.uio.no
