Understanding the solar eclipse jargon - WNEM TV 5

Understanding the solar eclipse jargon

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With the total solar eclipse quickly approaching you’ll likely see plenty of articles about it. Many will mention things like path of totality or magnitude. What on earth do these terms mean?

Below we will break down just a few of the words or phrase your likely to see or hear in regards to the August 21 total solar eclipse.

  • Total eclipse: This one is what we will experience in less than two weeks. A total solar eclipse is when the moon’s Umbral shadow crosses the Earth and the moon is close enough the earth to cover the sun. During the maximum phase of a total eclipse the Sun’s disk is completely blocked by the moon. During this time the sun’s corona is then (and only then) safely revealed to the naked eye.  Solar eclipse is more rare than a lunar eclipse
  • Path of Totality or just Totality: You’ll hear this one often. This refers to the maximum phase of a total eclipse. Totality is the period between when the eclipse begins and ends. It is when the sun is completely covered. It can last anywhere from mere seconds up to 7 minutes and 32 seconds.  Michigan is not in the path of totality we will only see a partial eclipse.
  • Partial eclipse: This is when the Moon’s penumbral shadow crosses earth. This is when the moon appears to block part (but not all) of the sun’s disk. Here is Michigan about 80% of the sun will be covered.
  • Umbra or umbral shadow: The umbra is the darkest part of the moon’s shadow. Within the umbra the sun is completely blocked (total eclipse).
  • Penumbra or penumbral shadow: The penumbra is the weak or pale part of the moon’s shadow. In this the sun is only partially blocked. What we will see here in Mid-Michigan.
  • Magnitude: This one is a little more in-depth. Eclipse magnitude is the fraction of the sun’s DIAMETER blocked by the moon. It is a fraction and is expresses as a percentage or decimal. Example 80% or 0.8. When there is a total eclipse the magnitude will have a value of 1 or greater. Here in Michigan we will see a magnitude of 0.8 or 80% of the sun covered during the eclipse.
  • Obscuration: This one often gets confused with magnitude. Obscuration is the fraction of the sun’s AREA covered by the moon. It’s also expressed as a percentage or fraction. The obscuration here at home will be the same as the magnitude 80% or 0.8.

If you come across any of these terms here’s an easy cheat sheet that may save you a Google search.

We are only 12 days away from the eclipse so be prepared for a once in a lifetime celestial show! 

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