TYPES OF SOLAR ECLIPSE

There are four different types of solar eclipse, partial, annular, total and hybrid eclipses.  Each of these is dealt with on this page.

Partial Solar Eclipses
 
Partial eclipses occur when the umbral shadow of the Moon does not touch the Earth and only the penumbral shadow touches the earth.  Because of this the umbral shadow will either pass over the north or south poles of the Earth. These eclipses occur when a new Moon falls close to the outer limits of the eclipse window i.e. early or late in the window.
 
As an example, the partial eclipse of February 5, 2000 occurred in the Southern Hemisphere and was only visible from Antarctica. This partial eclipse had an eclipse magnitude of 57.9%.  This means that the Moon covered approximately 58% of the solar diameter.  This only happened for a specific spot on Earth, and at a specific time, called the time of greatest eclipse. For a partial eclipse this point always occurs on the transition between night and day, because at that point you are closest to the shadow axis. At the point and time of Greatest Eclipse you will see the partially eclipsed Sun on the horizon.
 
Partial eclipses also occurred on July 1 & 31 2000, in the same eclipse window. Two solar eclipses in the same window are fairly rare. The first eclipse occurs near the South Pole and the second near the North Pole. They had magnitudes of 47.6% and 60.3% respectively.
 

A partial eclipse also occurs for any observers who are outside the path of totality or annularity during a total or annular eclipse.  The magnitude of the eclipse can vary from 0% to 99.99%, depending on where the observer is located.
 
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Annular eclipses occur when the Moon appears smaller than the Sun.   If you are in the path of annularity you will see the Moon begin to cover the Sun, eventually sliding in front of the Sun leaving a small circle of Sunlight around the Moon’s disk for anything from a few seconds to up to 12 minutes. The Moon then slowly uncovers the Sun again.
 
Because the Moon appears smaller than the Sun, the umbral shadow falls short of the earth's surface, and the portion of the earth’s surface experiencing annularity is described by extending the lines of the umbral path, as shown in the diagram.
 
As with partial eclipses, the instants of first and fourth contact refer to the beginning (ingress) and end (egress) of the lunar disk on the solar disk.  However because inside the path of annularity you are in the antumbral shadow the Moon will also begin and end movement inside the solar disk.
 
These instants are called second and third contact respectively. Second contact is defined as the instant that the Moon is first entirely within the solar disk, and third contact is when the Moon begins to leave the inside of the solar disk.
 
Another way to put it is; at first contact the penumbra begins covering the observer and at second contact the antumbral shadow cone starts covering the observer.

The Moon therefore covers 96% of the Sun and so about 4.4% of the Sun still remains uncovered at the instant of greatest eclipse. This is still enough to prevent significant darkening.
 
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The nature around you will change dramatically, as it gets quite dark.
 
During a total eclipse of the Sun, the ONLY place to be is in the path of totality.  Anywhere else and you will miss the show!
 
At first contact the penumbra covers the observer and the eclipse begins.  Matters proceed very similarly to an annular eclipse, with the Moon gradually covering the Sun.
 
Just before second contact, bright beads (Baily's beads) appear around the Moon's leading edge - these are caused by Sunlight finding its way through the deep valleys of the Moon. The last burst of Sunlight before totality begins leaves just one bead, known as the “diamond ring”. At second contact all Sunlight is cut off and the corona appears in all its magnificence.  For anything up to 7 min 31 seconds, day is turned into night, birds roost, and animals settle down for the night. A circular Sunset horizon appears as you are engulfed by the Moon's shadow.

Hybrid Solar Eclipses
 
This type of eclipse is fairly rare and is also known as an annular/total eclipse. The eclipse begins as an annular eclipse with the Moon’s umbral shadow just short of the earth’s surface.  But, because of the Earth's curvature, in the centre of the eclipse path, the Moon’s shadow is just long enough to “touch down” on the surface of the earth and the eclipse becomes total. The eclipse will remain total until near the end of the eclipse path when the shadow is once again too short to reach the surface and the eclipse once again becomes annular.  The hybrid eclipse of April 8, 2005 is such an annular/total eclipse.

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