Astronomy

Solar Eclipse



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An astronomical phenomenon that was once revered by cultures and feared by many, a solar eclipse occurs when the Sun, Moon and Planet Earth are in perfect alignment, with the Moon crossing the surface of the Sun, forming a shadow across the surface of the Earth. Even though the diameter of the Sun is 840,000 miles and the diameter of the Moon is 2,158 miles, they are both at a distance where they appear to be of the same size. Because of this astronomical coincidence, the Moon is able to cover the entire surface of the Sun. When an eclipse occurs, only a portion of the planet will be covered by the Moon's shadow, and this portion is made up of two parts: the umbra and penumbra. A total eclipse is what can be viewed from the umbra portion: this occurs when the Sun and the Moon are in such an alignment that light is completely obscured. The entire area under the umbra, a path that is known as the path of totality, streaking across the surface of Earth, becomes as dark as night time for a few minutes, whilst the magnificent corona can be seen in all its glory. A partial eclipse is when a portion of the moon covers a portion of the Sun's surface, though how much of the Sun's surface is covered depends on the positioning of the observer within the penumbra.

The Moon orbits the Earth once every 29 days in an elliptic fashion. In simple terms, this means that the Moon's orbit around Earth is not circular; it's elliptic. Simply put, the shape of the Moon's orbit is very similar to that of a rugby ball. This elliptic orbit causes the Moon to vary its distance from Earth: at its closest position in its orbit, the Moon is roughly 221,000 miles away from Earth; at its farthest point in orbit, 252,000 miles away. If a solar eclipse occurs when the Moon is at its furthest point, an annular eclipse occurs. This is when the Moon covers the whole surface of the Sun except for the edges of the Sun, therefore a ring of light surrounds the Moon. The affect is it still gets dark, but not totally dark like it would be during a total eclipse.

As the moon orbits Earth, it goes through a series of phases that causes its appearance to alter during each month. For a solar eclipse to happen, the Moon must be in its New Moon phase because here the Moon will be in front of Earth, and will be totally obscured from view because the side that is facing Earth will not be reflecting sunlight. This is in complete contrast to its opposite phase: the Full Moon phase, where the Moon is behind the Earth and is in full view of Earth because it's fully reflecting the sunlight. For a solar eclipse to happen, the Moon must be in its New Moon phase.

Before the advances of science and technology allowed us to explore and understand what solar eclipses are and how they occur, they used to strike fear in those of ancient civilisations and cultures. It has been documented that civilisation has held a fascination and interest in the solar eclipse for centuries, the earliest documentation dating back 4,500 years to the ancient civilisations of China, Babylon and Egypt. Each civilisation had their set of beliefs and ideas regarding the significance of an eclipse. The Chinese held the belief that during an eclipse the Sun was being consumed by a large dragon, so they used to bang drums, chant and scream in loud voices so to scare the dragon away. Once the eclipse was over and Sun revealed itself more and more, the Chinese celebrated as they thought the dragon was releasing the Sun out of fear of the noise they were creating. Other cultures believed that a solar eclipse was a sign from their Gods of significant troubles ahead. Now however, we know that a solar eclipse is nothing more than the Moon passing over the surface of the Sun. Despite that, there are still superstitious beliefs: in India, when the people witness and eclipse they lock themselves indoors out of fear, and it is believed that people should cleanse themselves during an eclipse. Solar eclipses are not only steeped with ancient beliefs and superstition, they have also been used as a milestone as part of historical research.

A solar eclipse can be viewed with a naked eye during the period of totality: where the Moon completely covers the surface of the Sun, where day turns to night. Viewing a solar eclipse either side of totality without the appropriate visual equipment is extremely dangerous and can lead to permanent eye damage. The safest way in viewing an eclipse is through a pin-hole projection, where the image of the Sun is projected onto a piece of cardboard or other material. Other viewing aids for solar eclipse are solar filters. Solar filters are very important, because they block 99.99% of the harmful sunrays.

To conclude: in order for a solar eclipse to occur, the Moon, Sun and Earth must be in perfect alignment. For a perfect total eclipse to happen, the Moon must be at the closest distance to Earth so that it can cover the surface of the Sun completely. The process of a solar eclipse is amazingly simple in the shape and vastness of the whole Universe, but to us more humble humans, we still find the event spectacular and awe-inspiring. It's an astronomical event that affects everyone that is under it, especially in the region of totality, but it must be viewed with health and safety as top priority, along with enjoyment!

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