Monday, August 3, 2015

Is Seeing Believing?

In Holy Scripture there are many descriptive passages engendering wonder at the glory of the sun, moon, stars, and planets. Bible authors described what they saw in the heavens and assigned spiritual significance to their perceptions. One poetic King James passage describes the rising and setting of the sun as inspiring devotion and worship: “From the rising of the sun unto the going down of the same the Lord’s name is to be praised” (Ps. 113:3 KJV). Along with many descriptive and devotional passages with respect to heavenly objects, we note that the real motions of the earth such as rotation on its axis or revolution in its orbit were not discussed or envisioned by scripture authors. It remained for Copernicus (1473-1543) to set humanity on the path of discovery concerning Earth’s real motions.    

Instruction in astronomical basics is a fascinating, yet challenging task for science teachers. Astronomy was one of my favorite earth science topics as a classroom instructor and the favorite of many students. The subject matter is visually accessible every clear night. To a lesser extent daylight hours also provide lessons in astronomy, sometimes overshadowed by the realities of meteorology.

Astronomy is a multidimensional discipline. For purposes of our discussion we mention only two branches: observational and physical astronomy. We acquire our first astronomical lessons as young children. The purest form of observational astronomy consists of naked eye observation. Observations prior to the advent of reflecting and refracting telescopes beginning in the 17th century were all naked eye observations. If the morning sun arose from the horizon and the evening sun descended below it, what reasonable person would deny that these motions were real? In the sphere of astronomy, “Seeing is believing” requires some qualification.

One effective method of science instruction is to guide students through the historical process of discovery. For example, what did the ancients see in the sky? They visually observed movements of the sun, moon, planets, and stars. What did they conclude about what they saw? In our day, if we did not possess modern knowledge of the Earth’s rotation and revolution, would we conclude from visual observations of the sun, moon, planets, and stars that we are standing on a rotating Earth? Would we conclude most sky objects do not really move around us daily? Perhaps we would not. Aristotle (4th century BC) and Ptolemy (2nd century AD) claimed they couldn’t feel the motion of a rotating Earth. After all, dropped objects fall straight down, and they could not feel the motions of an Earth rotating under them. This was a strong argument in their day!

Little known 3rd century BC Greek astronomer and mathematician Aristarchus had a brilliant insight into Earth’s real motion. He was an original heliocentrist. He claimed the sun was central and that Earth rotates on its axis and revolves about the sun. Aristarchus’ insights did not survive because they were difficult to prove. Copernicus’ conclusions were viewed with suspicion for the same reason. In today’s introductory astronomy classes, “Seeing is believing” may be a difficult principle to reconcile in every case, especially when we interpret perceived motion.

When we teach introductory astronomy to beginners, we teach the difference between real and apparent motion early in the course. Do we believe what we see? Is seeing believing? When we are in a train station, is the movement of a train on an adjacent track real or apparent? Are we moving or are the coaches on the next track moving? In the simplest example, if we turn our head from right to left and we observe stationary objects passing before our fixed gaze from left to right, do we observe real or apparent motion? If our muscle (kinesthetic) sense tells us clearly what really moves, the distinction is easy. If our senses do not give us these clues, we may not correctly judge the difference between real and apparent motion. (If apparent motion results from real motion, the direction of motion is always opposite.)

Apart from discovering truths of astronomy, we must review the lesson of seeking correct interpretations of our observations in the world of nature. I Thessalonians 5:21 exhorts us to test all things: “Prove all things; hold fast that which is good. The passage usually applies to spiritual knowledge, but we may apply its truth to superstition or errant interpretation in any sphere of existence, including the natural world.