The Umbra Eclipse: In The Shadow Of The Moon

The word umbra is Latin for shadow. The term describes the part of a shadow that is completely dark. In terms of a solar eclipse, when the umbra portion of the moon’s shadow passes between the sun and the earth it can completely obstruct the view of the sun creating a total eclipse. A total solar eclipse is usually a short lived event and because it covers less than 1 of the Earth’s surface, it can only be seen in relatively small areas.

Throughout history solar eclipses have been seen as omens or the result of angry gods. Stonehenge, http://www.stonehenge.co.uk/, on England’s Salisbury Plain, is believed to have been built in an attempt to predict astronomical events, including eclipses. As technology and science advanced however, the solar eclipse provided an opportunity to observe and study the sun’s corona (outer layer of the sun’s atmosphere) which is normally not visible because the photosphere is too bright. During an eclipse in 1868, it was discovered that helium existed in the sun’s corona, Einstein’s theory of relativity was proven during an eclipse in 1919 by demonstrating that gravity can bend light. Today scientists study the corona to answer questions about solar flares and determine the composition of the atmosphere surrounding the star.