The Soothing Twilight
WHAT if darkness came suddenly each evening, as though a light switch had been turned off? Would you miss the twilight?
For many persons twilight is a treasured part of the day. They are enchanted by the changing colors and the gradual darkening of the sky. The evening twilight has inspired many artists to express themselves beautifully.
What Causes Twilight?
If there were no atmosphere around the earth, complete darkness would set in abruptly at sunset, like switching off a light. This is what happens when the sun dips below the horizon on the atmosphereless moon.
But on earth, when the sun disappears from sight in the evening, it continues for a while to illuminate the upper layers of the atmosphere. Earth’s atmosphere, with its many dust particles, continues to reflect sunlight, and supplies the earth with indirect light, or twilight. Thus darkness comes on gradually as the sun sinks farther below the horizon and illuminates less of the atmosphere above. The same phenomenon, but in reverse, occurs in the morning before sunrise. This, too, is called twilight, or, more often, the dawn.
Not all people on earth experience twilight to the same extent. This is because its duration varies at different latitudes. For example, in equatorial regions, at lower latitudes, the sun rises and sets almost vertically in relation to the horizon. Therefore it quickly “travels” down below the horizon until its rays do not touch even the highest layers of earth’s atmosphere. So twilight is very short near the equator.
However, in temperate regions, at higher latitudes, the path of the sun is slanted in relation to the horizon. Thus the sun takes longer to “descend” below the horizon to a point where its rays do not reflect on the atmosphere above. So twilight is longer there.
The duration of twilight will also vary at the same location during different seasons of the year. This is because of the inclination of the earth’s axis, causing the sun to appear at different positions in the sky at different times of the year as the earth moves around the sun.
Intervals of Evening Twilight
Twilight is sometimes separated into three intervals. First, there is the so-called civil twilight. It begins at sunset and lasts until the sun has dropped six degrees below the horizon. This is about as long as natural illumination permits ordinary outdoor activities and is when the first star appears.
Next comes nautical twilight, which continues as the sun sinks to twelve degrees below the horizon. At this point only general outlines of objects are discernible, the horizon appears indistinct and the brighter stars can be seen.
Finally astronomical twilight terminates when the sun reaches eighteen degrees below the horizon. Illumination from the sun is then imperceptible and “complete” darkness sets in.
The twilight sometimes presents a beautiful display of colors. When the sun is about two degrees below the horizon, a gorgeous purple may appear. This color is a highly variable phenomenon, but usually it rapidly broadens and seems to intensify, so that it gives a purple hue to the objects on the ground. The purple light lasts till the sun is about six degrees below the horizon. It is said that it is produced by scattering of sunlight from a haze layer about six miles high.
Now an indescribable blue color may seem to spread all around in the air and on the ground. Especially is this the case where there is a wintry snow-covered landscape. This twilight glow in the sky gradually sinks into the horizon and disappears as the sun approaches eighteen degrees below the horizon.
Effect on Plants and Animals
The gradual changeover from day to night provides both plants and animals a time of adjustment. Some plants slowly fold their leaves and flowers in twilight, seemingly to hide their frail parts from the night. Other plants seem to open themselves to catch or inhale something they missed during the daytime. They are evidently controlled by a built-in clock, set by the changes of light and darkness.
A similar process occurs in the animal kingdom. Some animals quiet down and head for their nests and lairs to sleep. But other animals wake up and get ready for their nightly activities. This rhythm of the animals was poetically expressed nearly 3,000 years ago by a Bible psalmist of Israel, who gives Jehovah God the credit for this, saying: “You cause darkness, that it may become night; in it all the wild animals of the forest move forth.”—Ps. 104:20.
Effect on Humans
Humans, too, can find twilight a wholesome, pleasant part of the day. It gives time for adaption of the mind to the coming night, and a pleasant adjustment of the eyes from daylight to darkness. It can soothe an uneasy mind and often creates a marvelous feeling of contentment. “Not until twilight come refreshment and alleviation,” says a poet.
Twilight can be an ideal time for meditation. It invites man to lift his thoughts to higher levels than his daily tasks require. It tunes in man’s mind to deeper thinking and helps him to search his heart.
But one must be on guard too. For the effect of twilight upon a man’s emotions may also lead him astray. His thoughts may wander off and awaken his erotic desires, inducing him to satisfy them in an immoral way. Wise King Solomon warningly wrote about this in the Bible book of Proverbs. He describes how a young man in want of heart passes along on the street near a prostitute’s house “in the twilight, in the evening of the day, at the approach of the night and the gloom.”—Prov. 7:7-9.
Surely this highlights the need for Godfearing persons properly to use the twilight period, as well as other hours of the day. There is vital need to think on the clean and exalted principles expressed in God’s Word the Bible, and to lift up one’s thoughts in prayer to the Grand Creator of the soothing twilight, Jehovah God.