Just Right Moon

In a few days, a total solar eclipse will cross the full width of the United States, and you can give credit for that to the just right moon.

We have looked at the “how” and “why” of total solar eclipses. We have considered what value total solar eclipses have. We have seen that a total eclipse helped to confirm a very important scientific principle. Also, we pointed out that solar eclipses happen only at the time of the new moon when the Moon is between the Earth and the Sun.

A new moon occurs about every 29 days, so why doesn’t an eclipse happen at each new moon? That’s because the plane of the orbit of the Moon around the Earth is about five degrees off from the orbital path of the Earth around the Sun. Because of that difference, a solar eclipse happens only when the Moon crosses the path of Earth’s orbit around the Sun (called the ecliptic). A TOTAL solar eclipse happens only when the Sun and Moon are exactly aligned.

What would happen if the orbit of the Moon were on the same plane as the ecliptic? At every new moon we would have a total solar eclipse, and at every full moon, we would have a total lunar eclipse. So the Sun would go dark in the daytime somewhere on Earth every month, and the full Moon would also go dark monthly. The influence of the Sun’s gravity on the lunar orbit might cause more serious problems.

No other planet has a moon that plays such an important part in creating an environment suitable for life. The Moon is right where it should be to serve life on Earth. Our just right Moon lights the night, creates the tides that clean our estuaries, stabilizes Earth’s rotation, and occasionally provides a total solar eclipse that gives us a glimpse of God’s marvelous design of our solar system.
–Roland Earnst © 2017