What Syzygy Means

What Syzygy Means

Syzygy is an interesting word used in astronomy. It’s a great word for Scrabble, but my kids quit playing with me when I used it once. You might wonder what syzygy means. Let me explain.

This spring brings an unusual view of the solar system. If you get up before the Sun now through May, look to the east, and you will see four planets that shine very brightly. The planets from left to right are Jupiter, Venus, Mars, and Saturn. All of them will be bright enough to see with the naked eye. With binoculars or a small telescope, you will also see some of the moons of Jupiter and Saturn. Astronomers call an alignment of planets like this a syzygy.

We can see these planets in this rare alignment because they orbit the Sun in the same plane, called the ecliptic plane. This is not just some happy accident but is a critical factor in the survival of life on Earth. Objects coming into the solar system along the ecliptic will not collide with Earth because the planets that lie further out in the solar system will intercept them long before they can reach our planet.

We have actually seen Jupiter intercept a comet coming toward the Sun along the ecliptic. The fireball the impact produced was larger than Earth’s diameter. This solar system design is so complete that the gravitational fields of the outer planets overlap so that nothing from outside the solar system can get to the Earth. The only “planet” not in the ecliptic is Pluto, which is inclined to the ecliptic. For that reason, scientists say that Pluto is not a planet but a captured object.

The design of the solar system is far more complex than most of us understand. The more we travel in space, the more we see the effect of not having a designed protection system. As science deals with space travel, the wisdom and planning of God become apparent. Take a few minutes on a clear morning before the Sun comes up to go out and look and wonder at how “The heavens declare the glory of God” (Psalms 19:1). Now you know what syzygy means, and you can use it the next time you play Scrabble.

— John N. Clayton © 2022

References: apod.nasa.gov for April 20, 2022, and earthsky.org.