What is a solar Eclipse?

A solar eclipse is a spectacular thing to behold, and they are relatively rare events – each Eclipse is visible only from a limited area.

When the New Moon moves in-between the Earth and Sun, and so blocks the rays of the sun, it casts a shadow on parts of the Earth. The blocking of the Sun’s rays is a solar eclipse

The shadow that is cast by the Moon is not large enough to cover the whole planet, the shadow is always limited to certain areas. The area covered by the shadow changes, this is because the Earth and Moon are always moving (the Earth moves on its axis as it orbits the sun, and the moon is orbiting the Earth).

Different types of solar eclipses

Many people don’t realise it, but there are actually 4 different types of solar eclipse. Just how much of the Sun is eclipsed depends on what part of the shadow cast by the Moon falls on Earth. The four types of solar eclipse are:

Partial A partial solar eclipse occurs the shadow cast by the Moon only partially obscures the sun
Annular This type of eclipse happens when the Moon’s disk is not large enough to obscure that of the Sun. When this happens, the outer edge of the Sun remains visible and forms a fiery ring in the sky – it is this type of eclipse that we most often see in movies.
Total A total eclipse occurs when the Sun is completely obscured by the Moon, and this can only happen when the Moon is near the perigee - this is the point where the Moon’s orbit brings it closest to Earth.
Hybrid A Hybrid solar eclipse also referred to as annular-total eclipses, are the most uncommon. These happen when the same eclipse shifts from annular to total, or vice versa.

The most common types of eclipse are partial

Solar eclipses look mostly partial

Any solar eclipse is visible only from within the part of the planet where the shadow of the Moon is cast. The closer to the centre of the shadow that an observer is, the larger the eclipse will look.

The different types of solar eclipse are normally named after their darkest spots, the exception to this the hybrid eclipse. In most places, and for the majority of the time the event is occurring, total, annular and hybrid eclipse's all look like partial solar eclipse's.

They only occur during a new moon

For a solar eclipse to even take place, the Earth, Moon and Sun need to be aligned in a straight line. A rough alignment of these three celestial bodies occurs each lunar month, at the New Moon. While this is true, why doesn’t a solar eclipse happen with every New Moon?

The path that the Moon takes around the Earth is inclined at approximately a 5° angle to the Earth’s orbital path around the Sun – this is called the ecliptic. The areas where the path of the Moon crosses the path of the ecliptic are named the lunar nodes.

An ideal alignment of Earth, Moon and the Sun can only happen when the New Moon is close to a lunar node. These moments happen at close to 6 months intervals and they last roughly 34.5 days.

This period is known as the eclipse season, and it is only during this period of time that a solar eclipse can happen. If there happens to be a Full Moon during this time, then we are treated to a lunar eclipse.

Never look right at the sun

Whether there is an eclipse or not, looking directly at the Sun is never a good idea – not without eye protection. The radiation emitted from the Sun can burn the retinas of our eyes, which can lead to permanent damage and even blindness.

The safest way to observe a total solar eclipse is by wearing special eclipse glasses, or you can project an image of it using a pinhole projector.

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