Yesterday we talked about the upcoming total solar eclipse and the fact that the Moon can completely hide the Sun from view. That seems very strange since the Sun is about 390 times larger than the Moon. By a “marvelous coincidence” the Sun is 390 times farther away than the Moon. Since the Sun is 390 times farther away, it appears to be 390 times smaller. For that reason, when we see the Moon and the Sun in the sky, they appear to be the same size.
The Moon can exactly cover the Sun’s disc which we call the photosphere. At the same time, in a total eclipse, we can see the chromosphere, which is the very bright atmosphere surrounding the Sun. We can also see what is called the corona–jets of hot gas which follow the lines of the Sun’s magnetic field. Under normal circumstances, the chromosphere and corona are invisible because of the glare from the photosphere.
Scientists have learned much about the Sun by studying what we can see only during total solar eclipses. Only during a total solar eclipse can scientists study the “solar wind” which sends out streams of particles called coronal mass ejections (CME). CMEs can travel all the way to Earth and knock out communication satellites or terrestrial power grids. Just as scientists work to predict weather on Earth to avoid catastrophes, they want to learn how to predict CMEs to prepare for something that could potentially knock out power or communication to large areas of our planet.
Scientists have also learned some interesting things about the Sun’s temperature during total eclipses. They had measured the temperature of the Sun’s surface to be 6,700 to 11,000 degrees F (3,700 to 6,200 degrees C). However, by observations made during total eclipses, they found that the temperature of the chromosphere is up to 14,000 degrees F (7,700 degrees C) and the corona is 3.5 million degrees F (2 million degrees C)! They are still trying to discover how that is possible.
Was it mere coincidence that the Moon can exactly cover the Sun? We think that God designed it that way so that we can learn how “the heavens declare the glory of God” (Psalms 19:1). We think it is not just a “marvelous coincidence,” but another example of wisdom and purpose in design. Tomorrow we will tell you about what is probably the most significant scientific discovery made during a total solar eclipse.
–Roland Earnst © 2017
