Blog Five, September 5, 2025

Once for all I have sworn by my holiness;

I will not lie to David.

His offspring shall endure forever,

his throne as long as the sun before me.

Like the moon it shall be established forever,

a faithful witness in the skies.” (Psalm 89:35-37 ESV)

Faithful Witnesses in Scripture

Only three entities are called a “faithful witness” in Scripture. One is obvious: the term is used more than once with Jesus Christ (Jeremiah 42:5; Revelation 1:6). One other person, Antipas, the martyr from the church at Pergamum, is given this description (Revelation 2:12-13). The third entity is an inanimate object: Earth’s Moon, given this descriptor in Psalms.

What makes the Moon a faithful witness? Planet Earth and its only natural satellite, the Moon, are locked into a synchronous orbital pattern that is breathtakingly precise. How precise?

One orbit of the Moon around Earth takes 27.322 days. This period is the basis of our month. Actually, since the Earth is orbiting the Sun, moving at 67,000 miles per hour, the Moon’s orbital period is a little longer, roughly 29.5 days (close to our month). The word month is derived from “Moon.”

The Moon, like the Earth, is also spinning on its axis, but very slowly relative to Earth’s 1000 mph speed. In fact, the Moon’s revolution period (one turn on its axis) takes 27.322 days. If that number looks familiar, it is because if is identical (to three decimal places) to its orbital period (see the paragraph above!).

This exact timing means that from Earth we see only one side of the Moon, giving us our phrase “the far side of the Moon” or “the dark side of the Moon.” Actually, it is not dark; at times, the Sun shines brightly on the far side… we just can’t see it from Earth. The term is “tidal locking,” and the Earth / Moon connection is one example. This is an effect of gravity – the larger body causes the smaller to synchronize into the precision we see.

This feature of our natural satellite gives rise to the legend of “the man in the moon.” This arrangement is a wonder in itself.

• The Milky Way galaxy travels through space at approximately 600 kilometers per second, or about 1.3 million miles per hour.

• The Sun and its solar system, orbits the center of the Milky Way galaxy at about 140 miles per second (220-230 kilometers per second, approximately 500,000 miles per hour).

• As mentioned, Earth’s speed around the Sun is about 67,000 miles per hour (107,000 kilometers per hour), which is equivalent to approximately 18 miles (30 kilometers) per second.

• Earth spins on its axis at 1000 mph (one revolution per day).

• The Moon's average orbital speed is about 2,300 mph (1.022 kilometers per second); its speed varies due to its elliptical orbit, ranging from about 1 km/s to 1.1 km/s.

• The Moon's rotational speed is approximately 10 mph (16.7 km/h) at its equator.

Remarkably, with this array of elliptical orbits, orbital speeds, revolutions, and angular momentum, an Earth observer sees the man in the moon anytime the Moon is out. With all this motion, the Moon is faithful to show us its same face.

The proclamation in Psalm 89 is rooted in scientific fact. The Moon is aptly named “the faithful witness in the sky.”

D. E.