What is an Eclipse?

by Rupali Rao, August 19, 2017

Eclipses have invoked fear, awe, curiosity, myths and legends throughout the history.  People have tried to come up with an explanation to understand where Sun disappeares temporarily and they have constructed various theories around it.  Ancient Greeks believed that eclipse is the sign that God’s are angry and it is going to be resulted in destruction; Indians believed that an angry demon Rahu swallows the sun and that’s why it disappears for sometime whereas people in Vietnam believed that a giant frog eats up the sun.

The term eclipse is mostly used to describe either solar eclipse or lunar eclipse.  Moon goes around earth and earth goes around sun. When earth comes between sun and moon, it blocks sun’s light to moon and it is called lunar eclipse.  It happens because earth’s shadow falls on moon. When it happens moon looks red or orange. This is one of the reasons that made people realize that earth is round, before that they used to think that earth is flat.

Solar eclipse happens when moon comes in between earth and sun and blocks the sun’s light. During solar eclipse moon cast shadow on earth. Solar eclipses happen during day time. When it happens, then the daylight dims, it seems as if it is twilight and if in case it is full eclipse then the day becomes as dark as night. This change in the daylight is so overpowering that animals will sometimes start behaving as if it is night time. Birds would stop chirping, cows head back to shed thinking that it’s time to settle down etcSolar eclipses lasts for few minutes only.

Solar eclipse is the most spectacular astronomical event and a lot of people are very excited about the upcoming total solar eclipse passing through the U.S. The solar eclipse on August 21, 2017 will be the first total solar eclipse in U.S. in 38 years. The last was in 1979, only in the northwest part of the country. Though the total solar eclipse can be seen from Oregon to South Carolina, everyone in the US will see at least a partial eclipse. Those who are not in US, they can watch the live broadcast of the event hosted by NASA. The next solar eclipse, which will be quite similar to the eclipse on August 21, will be recorded in 2024.

The event is expected to last for two daylight hours, with two minutes of complete darkness. It is a scene of an unimaginable beauty.

The great total solar eclipse will darken the skies in the United States all the way from Oregon to South Carolina. The people of this area are in for an unforgettable experience.  

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The most famous part of a total solar eclipse is the ‘diamond ring’. When moon covers the entire disc of sun but seconds before it happens, the sun’s corona forms a ring around the moon and the leftover part of the sun shines brightly at the top, and it gives impression of a diamond ring.

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The wonderful sight of total solar eclipse generally happens on a new moon day. In a total eclipse, the disk of the moon blocks out the last silver light of the sun making only outer line visible.

Solar eclipse is exciting but looking directly at the Sun can be harmful for the eyes, even when it is partially covered by moon. Number of advisories is provided against looking at the sun directly, because of which people assumed that eclipses are dangerous.  This is not the case at all. It is the Sun that is dangerous- always. As the Sun emits infrared rays, that can damage the eyes. Many people who wait to watch the eclipse should know that there are safe ways to watch eclipse:

  • One can use solar filters, such as eclipse glasses or special telescopes to watch solar eclipse but never naked eyes.
  • Look at the sun with solar filter glasses only while the eclipse is partial, that is the crescent sun.
  • You can look at the Sun directly when the eclipse is total, i.e. Sun is covered fully by the moon. It generally lasts from few seconds to couple of minutes.
  • Don’t look at the total eclipse with the sun filter glasses because then you won’t see anything.

There are certain things that you shouldn’t use while watching solar eclipse. They are:

  • Sun glasses
  • Old colour film negatives
  • Black and white film that contain no silver

It is because these materials have very low visible light transmittance level, but they transmit an unacceptably high level of near infrared radiation that can cause thermal retinal burn.

Solar eclipse is a beautiful, awe-inspiring celestial event that can be enjoyed by everyone if proper precautions are taken for eyes to view this by using proper glasses or telescope and not looking at the sun directly.  It is one of the most impressive and grandest natural spectacles, a sight to remember forever.

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