Space Dimensions and Lunar Motion

We have had several questions and comments precipitated by the eclipse on August 21. Most of them centered around the fact that the Moon’s motion across the Sun was so slow. In reality, the lunar motion is very fast. The speed is a function of the Earth’s rotation as well as the Moon’s revolution around the Earth. However, when compared to space dimensions, lunar motion can seem slow.

The Moon moves with an orbital speed of 2,288 miles (3,683 km) per hour, taking about 28 days to complete its journey around the Earth. Although that sounds fast, it is quite slow in relation to the size of the cosmos. Other moons going around other planets travel at higher speeds. Io, one of the moons of Jupiter, whizzes completely around the planet in less than two days. While our Moon travels at the speed of a rifle bullet, it is 80 times slower than the speed of meteors. Saturn travels ten times faster than the Moon.

The reason we are not aware of the speeds involved is because of the incredible size of the creation. We see meteors moving fast because they are close to us. Meteors are pieces of space junk whizzing through our atmosphere so quickly that they burn up from friction with the air. The moon is over 239,000 miles (384,633 km) away, so its motion appears to be much slower.

When we look out into the night sky, we are looking far into the past. By the time we see the light from stars like Albireo, that light has traveled 430 light-years. That star is actually two stars spinning around each other. Even though they are orbiting each other and astronomers have been watching them since the seventeenth century, we have not seen them change position.

Space dimensions are beyond our comprehension, and the size of the cosmos affects what we see and how we see it. Understanding that should give a whole new significance to the words of the song How Great Thou Art. It should also expand our understanding of, “The heavens declare the glory of God; the skies proclaim the work of his hands” (Psalms 19:1).

Data from Astronomy magazine, July 2017, page 10.
–John N. Clayton © 2017