Mr. Dan Kuiper, science teacher in Covenant Christian High School and member of Hope PRC in Walker, Michigan

Earth is part of the Milky Way galaxy, a spiral galaxy that contains an estimated 100 billion stars and stretches an incomprehensible 100,000 light years in diameter.1 On the darkest nights, we are able to view only a minuscule percentage of those stars with the naked eye and, yet, they act as an innumerable host that declares God’s glory. When we sit in stillness under the night sky and consider the work of God’s hands, we are reminded that He has set each star in its place and calls each one by name. Their nightly appearance is a constant reminder that our almighty God is able to fulfill all that He has promised.

Yet, for many of us, only a handful of stars is visible when we peer into the night sky. As industrialization of the world has increased, so has the use of outdoor, arti­ficial lighting. The result has been pollution of the night sky with light. According to a recent study, 80 percent of the world’s population is affected by light pollution. In the United States and Europe, 99 percent of the pub­lic is unable to experience a natural night.2 The wide­spread use of artificial light interferes with night vision and diminishes our ability to detect the natural light of the stars. In a similar way, with spiritual application, we will see that the pursuit of earthly pleasures clouds our view of the light of God’s Word.

Vision

In order to understand how light pollution interferes with the ability to see the stars, a brief description of how the eye functions is helpful. The eye contains photoreceptors, which are specialized cells located in the retina that are responsible for receiving and transmitting light. These cells contain pigments that are sensitive to light and are able to convert the energy from light into electrical signals. When light enters the eye, it passes through the cornea and the lens, and is focused onto the retina, where it is absorbed by the photoreceptor cells. The photoreceptors then send signals to the brain through a network of neurons. The brain interprets these signals and creates the images that we see.

The retina contains two main types of photorecep­tors—rods and cones. Cone cells contain pigments that are sensitive to different colors of light. There are three types of cone cells, each containing a different pigment that is most sensitive to either blue, green, or red light. When light enters the eye, it stimulates the appropriate cone cells, which then send signals to the brain indicat­ing the presence of that particular color. The extent to which each of the different types of cones is stimulated allows for the detection of the whole range of colors. Rod cells, on the other hand, are unable to distinguish between colors of light. However, they contain a pig­ment called rhodopsin that is 100 to 1000 times more sensitive to light than the pigments found in cone cells. When light enters the eye and hits rod cells, rhodopsin absorbs the energy and generates an electrical signal. The strength of the electrical signal is proportional to the intensity of the light, allowing the brain to distin­guish between different levels of brightness.

In the presence of high-intensity light, the rhodopsin present in rod cells is broken down and the rods become inactive. Cone cells, therefore, are the primary photore­ceptors used during daylight and under bright artificial light. When day transitions to night, the brightness of light decreases. Cone cells, which require greater bright­ness, begin to deactivate and the rhodopsin in rod cells is gradually reassembled and reactivated. Therefore, our eyes become more and more sensitive to dim light as darkness develops and rod cells are increasingly activat­ed. It takes about 20 to 30 minutes for this reactivation to occur, which explains why it takes about that long for our eyes to acclimate when we step into the dark night from the bright lights inside our homes.

Light pollution

Having an understanding of how the eye detects light, we now turn to the topic of light pollution. Light pollution refers especially to the use of unnecessary or excessive artificial lighting. There are two main types of light pollution that affect our ability to see the stars: local light pollution and skyglow.3 Local light pollution, also called line-of-sight light pollution, comes from nearby light sources that send bright light directly to our eyes. Examples are bright street lights, parking lot lights, or flood lights of homes that are directed sideways towards the eye. That light interacts with our rod cells, degrading rhodopsin, and reducing our sensitivity to light. This reduced sensitivity contributes to our inability to detect the light of dimmer stars.

The second type of light pollution, skyglow, is the re­sult of the scattering of light in the atmosphere. Earth’s atmosphere consists of numerous particles, such as dust, water vapor, oxygen molecules, nitrogen molecules, and pollutants. When light interacts with these particles, it gets absorbed and re-emitted in different directions. This causes light to scatter through the atmosphere before it reaches our eyes. The amount of scattering depends to a large extent on the wavelength of light. Sunlight consists of all the colors (ROY G BIV) of light, each having a different wavelength. Colors on the red end of the spectrum have longer wavelengths and colors on the blue end have shorter wavelengths. Shorter wave­length light (for example, blue light) scatters more than longer wavelengths (for example, red light). Because of blue light’s short wavelength, it scatters through the at­mosphere to a greater extent than other colors present in the sun. It bounces through the atmosphere, filling the sky with blue light that eventually reaches the eye from all directions. This is the reason the sky appears blue on a clear, sunny day.

The scattering of sunlight in the atmosphere is a nat­ural process. However, at night, most light scattering comes from the multitude of artificial lights present in our surroundings. That light, especially when emitted sideways and upwards, causes the sky to glow. When the sky is dark, rod cells can detect the contrast between the light of very faint stars and the dark background. When skyglow exists, the light of dim stars is blocked from our vision.

The somewhat recent switch from incandescent to LED bulbs has contributed to an increase in light pollu­tion. Typically, light from incandescent bulbs produces warmer yellow and amber tones (towards the red end of the spectrum), while LEDs give off harsher white and blue tones. Because of the amount of scattering that oc­curs with blue light, LEDs tend to contribute more to skyglow than incandescent lights. In addition, rods are more sensitive to blue light, so the blue light of LEDs de­grades rhodopsin more rapidly than the warmer colors of incandescent bulbs.

Distracted by light

By way of analogy, there is a spiritual lesson to be learned from an understanding of light pollution. Artificial light is needed in a world that is busy in the pursuit of earthly pleasures. Much of that light pollutes the sky, distracting our eyes and diminishing our ability to see the light of the stars. In a similar way, our own busyness with the cares of this world can distract us from spending time in the light of God’s Word. Psalm 119:105 teaches that God’s Word is a “lamp unto [our] feet, and light unto [our] path.” God’s Word serves as a guiding light in our lives. It provides us with wisdom, direction, and encouragement. It points us to Jesus, who is the “light of the world” (John 8:12). Because this is the case, we are called to set the Lord before our eyes at all times (Ps. 16:8) and look to “Jesus the author and finisher of our faith” (Heb. 12:2).

However, it is not uncommon to find our eyes and minds distracted from God’s Word by all that glitters and glows in the world around us. Just as light pol­lution clouds the brightness of the stars, the constant bombardment of information, entertainment, and ma­terialism can cloud our sight of Christ and His Word. We may become more concerned with accumulating wealth, status, or power than serving God as com­manded by His Word. We may become self-centered, forgetting that we are called to love and care for our neighbors as ourselves. Even when we go to church, it can be the case that our minds are so distracted by the cares of this world that we fail to focus properly on the preaching of God’s Word. In a society that relies heavi­ly on technology, distractions from God’s Word can be even more prevalent. We often find it difficult to discon­nect from our digital devices, social media, and other on-line platforms. The bright light of screens stimulates the eyes and captures our attention, distracting us from meditating on the light of God’s Word as we ought. As our eyes focus on all that shines in the world around us, they lose the ability to see Christ, who is our Light and our Salvation.

In the midst of a busy and distracting world, may the words of Psalm 46:10 be brought to mind: “Be still, and know that I am God.” The pursuit of earthly glo­ry, riches, possessions, and power can bring momentary satisfaction, but they do not have the power to bring true peace and joy. They will fade away like everything else here below. Therefore, we are called to put away the pursuit of earthly things, turning off those dis­tracting lights, in order to set our minds on Christ. We must intentionally make time each day to put down our work, set aside our screens, stop the games, take up the Scriptures, and quietly meditate on the promises of that glorious Word. That Word is the revelation of Christ who is our “shield” and “exceeding great reward” (Gen. 15:1). We belong to Christ! Because He was forsaken, we are forgiven and have been made partakers of all the benefits of salvation. In Him we have fullness of joy and are fully satisfied. As those who belong to Him, we are able to rest in the confidence that the God who made this universe with more stars than we can count protects and preserves us to the very end.

1 NASA: Solar System Exploration (Accessed 2023, March 25). Beyond our solar system. https://solarsystem.nasa.gov/solar-sys­tem/beyond/overview/.

2 International Dark Sky Association (2016, June 10). 80% of world population lives under skyglow, new study finds. https://www.darksky.org/80-of-world-population-lives-under-skyglow-new-study-finds/.

3 Space and Beyond Box (Accessed 2023, March 20). How to see stars and deep sky objects in a light-polluted city. https://space­andbeyondbox.com/how-to-see-stars-and-deep-sky-objects-in-a-light-polluted-city.