What is Twilight
Where all know what twilight is.
No, I am not talking about the book and the movie of the same name. I am talking about the time of day between daylight and darkness. It is considered twilight when the earth goes through this daily transitions between whether it is after sunset or before sunrise. Twilight makes the sky appear pinkish as the light is spread across a blue sky and the sun is below the horizon. The hues of twilight take on the sun’s rays and scatter it across the atmosphere in a beautiful display of nature’s art.
Twilight occurs simply because we have an atmosphere.The moon has no twilight because the moon doesn’t have any atmosphere. Twilight occurs on Earth because the light from the sun is deflected through our atmosphere. This causes us to see the red sunsets. Red occurs in the sky because the blue light is scattered off dust in the atmosphere and it is only the red light that reaches us. The moon has a black sky and at bright light of the sun during the day.
Clouds and Twilight
Clouds and Twilight
How long twilight lasts depends on the clouds, air pressure, dust, humidity, temperature and other atmospheric conditions. It also depends on the angle between the rising or setting sun's path and the horizon. Both of these factors vary with the season, the decline of the sun, and the Earth's latitude.
Clouds can shorten the amount of time we have twilight and it can make twilight time darker. Dense clouds darken the sky, can obstruct the sunlight or prolong the amount of time twilight lasts. Clouds can also brighten the stages of twilight, if the sky is clear to the west and below the horizon, which would allow sunlight to reflect off of the clouds.
The Moon and Twilight
The Moon and Twilight
On Earth,some of the light spreads through small particles in the sky while there is still some light even though the sun is below the horizon.
Before the sun rises and again, after the sun sets, there is still some natural light from the upper atmosphere . The sky still gets some direct sunlight. This light partially reflects it back onto the Earth’s surface, which causes the sky to be illuminated. As twilight continues, the amount of natural light reduces until darkness arrives.
Science defines twilight by considering the position of the sun below the horizon.
The Definition of Twilight
Astronomers know there are three different kinds of twilight. When the time is twilight, we can see a pinkish tone in sky. The sun is just below the horizon, as the magnificent rays diffuse through the atmosphere create a gorgeous and soft display of colors that tell our sense of sight that twilight is here.
The astronomers classify twilight as:
- civil twilight
- nautical twilight
- astronomical twilight
Civil twilight begins when the sun goes down below the horizon at sunset. There is enough light to see, but this is the hour when we usually turn on the lights of the car, and we see the streetlights come on. You can see the brightest stars in the sky even though there is no moonlight yet. The official end of civil twilight is when the sun is six degrees below the horizon.
Nautical twilight starts when it appears to be dark outside. It begins in the morning before the sun rises, and begins again in the evening before nightfall occurs. Science defines nautical twilight as ending when a distant line of the horizon along the ocean stops being able to be seen against the sky. The illumination level is reduced and the night begins to take shape. Nautical twilight got its name because sailors on the ocean were able to navigate with the stars on moonless nights. The sun is considered to be twelve degrees below the horizon. Many people define this as twilight.
Astronomical twilight begins when the glow of the sky is gone. It ends when the sun is 18 degrees below the horizon. At this point. the astronomer can start to watch the stars, as long as there are no clouds obscuring their view. At this point in the day, scattered light from the sun can begin to be seen. The illumination in the sky is very slight, nearly imperceptible.
Twilight and Outer Space
Twilight from outer space does not show any sharp boundaries on the surface of Earth. Twilight appears as though it is spread across over a large area and shows a transition from light to darkness over a gradual period of time until night arrives. There are no sharp boundaries, only a shadow line on our planet that sometimes is called the terminator line
Twilight is an amazing phenomenon that occurs twice a day, everyday, and yet we often give little thought to the work nature does on a daily basis.
Viewing twilight is breathtaking. The colors we observe mark the start of a new time of day, a transition that on some levels prepares us for the changes we make in the course of our routines.
Twilight is so obvious, we don’t need to look at our watch to know whether it is dawn or dusk, yet in our busy lives, we rarely take the time to honor the awe of nature and the picturesque and spectacular beauty the sky gives us.