Total Solar Eclipse
During
a total solar eclipse part of the Earth's surface is in the shadow
of the moon. However, a total eclipse is possible only if the moon
disk is large enough, in order to cover the solar disk completely.
But the surface, which the shadow of the Moon covers, is relatively
small, and therefore a total eclipse - thus complete coverage of
the photosphere - can only be seen from a limited area of the
Earth. As the moon moves around the Earth and the Earth rotates
around its axle, the shadow moves over the Earth's surface and
produces a narrow strip, a zone of totality, broad up to 264 km,
from which a total solar eclipse becomes observable. This totality
zone is followed on both sides by an area broad some 1,000 km,
which is met by the penumbra; there the sun is only partly darkened
and from there the eclipse is partially observable.
Just before the total solar eclipse the sky and the asterisks
become visible. In the moment, when the Sun is completely covered,
a white, resplendent light surrounds the moon, the so-called corona
of the sun. The reason for this is the hot gas, which the Sub
sandblasts. A ring of reddish gas- the so called Solar chromosphere
pulls itself directly around the black disk of the Moon. Every now
and then out-shooting gas tongues, protuberances are also to be
observed from the Sun.
The outline the Moon is not completely circular, as there are
mountains and valleys. Directly before or after complete covering
it can seem that jets penetrate from the sun through these valleys:
Perl cord phenomenon. A total solar eclipse gives the view of the
impressive solar corona, which is otherwise hidden by the
brightness of the blooming of the Sun. The corona, the area of
which is the sun atmosphere, is not clearly boundered, but enters
gradually into the interplanetary gas.
If the Moon shifts itself in front of the Sun and is close enough
to the Earth, a total solar eclipse of max. duration of 7.5 minutes
takes place. A total eclipse is to be seen only in a closely
limited area of the Earth's surface and ranks among the rarest
eclipses. Close to one of the core shadow zones it appears as a
partial darkness. Here (s. picture down) the shadow of the Moon
reaches the Earth. From this area a total darkness can be observed.
Around the shadow is situated the penumbra, from which a partial
darkness is visible.
Circular solar eclipse
Since
the Earth and the Moon move on elliptical courses, the distances
between the Sun and the Earth and the Earth and the Moon are not
the same. If the Sun is nearer than normal and the Moon is at the
same time further, then the Moon appears to us somewhat smaller
than the Sun in the sky.
If a solar eclipse occurs at this time, the Moon does not cover
the sun disk completely; the outside ring of the Sun remains
visible, and the black Moon is to be seen around a brightly
radiating ring
This phenomenon is called a circular solar eclipse. In this case
the sky does not collude itself, and the corona is not to be seen.
If the Moon is too far distant from the Earth, in order to cover
the Sun completely, a bright edge of it remains visible. A circular
eclipse occurs, if the Moon on its way between Earth and Sun is
distant enough from the Earth, so that its shadow does not reach
us. The circular eclipse is visible in the narrow zone between the
two lines. Within the area of the two penumbra zones one sees a
partial eclipse .
Partial Solar Eclipse
If the
outgoing from the Moon core shadow cones do not pass too far from
Earth, then they can still come into the penumbra. In the penumbra
of a total solar eclipse observers see the Sun only partially
darkened. Likewise one sees the sun disk only partially covered,
the further one is distant from the totality zone.
