The opposite of the time of day when twilight is seen in the evening, between daylight and darkness. Daybreak, dawn, dusk, and night all mean exactly what they sound like: the coming or going of light.
Twilight is often used to describe an interval of time that is neither night nor day, such as morning twilights or evening twilights. It can also refer to any period of time during which there is a change from dark to light or vice versa.
The term does not have any scientific meaning and is merely an English creation that has been adopted by people around the world.
Twilight is usually associated with the end of daytime and the beginning of nighttime, but this concept is not found in all languages. For example, astronomers use the word "twilight" to describe an interval of time when sunlight is attenuated but still detectable. This occurs when the sun is below the horizon and begins to rise again.
In mathematics, physics, and astronomy, a twilight zone is a region of space where different phenomena occur due to the interaction of several factors. In mathematics, a twilight zone is a set for which no two elements are equal; set theorists call these sets maximal.
Twilight is defined as the span of time between (astronomical) dawn and sunrise, or between sunset and (astronomical) dusk. Thus, twilight exists at any time during the day or night when sunlight is still visible outside.
Dawn is the first light in the morning. At first, it is just a faint glow from the east as sunrise approaches. Soon enough, however, dawn brightens to reveal all the colors of the rainbow. As the sun gets higher in the sky, so does its temperature. By the time it reaches its highest point in the sky, it has become hot enough to evaporate water, which leads to the rise and fall of oceans and tides. This is why people used to think that the world was ending when it got dark out - because there would be no more daylight and thus no more chance of survival. Today, we know that this isn't true because astronomers know that there are stars outside of our galaxy that are much further away than the furthest object humans have ever reached (the edge of our solar system). These stars are too far away for anyone on Earth to see them tonight, but they will be visible in the morning when dawn comes.
Sunset is the last light in the evening.
The time between sunset and dusk is known as twilight. There is still light in the sky during dusk. Dusk is defined as the time when the sun is 18 degrees below the horizon and there is no longer any light in the sky. Sunset is the moment when darkness completely covers the Earth's surface after which dusk begins.
Sunset and dusk are important times because they mark the end of daylight saving time and the beginning of standard time. During these hours, the sunlight becomes softer instead of being directly overhead as at sunrise or just before sunset. Because shadows are longer at sunset, objects near the horizon are visible for a while after sunset, but then disappear into darkness.
Not only does the color change of the sky at sunset and dawn make them beautiful sights to see, but so do the sounds that surround them. The wind rustles through the trees and makes different noises at each hour after dark, and the crickets start singing about an hour after sunset.
Twilight comes in three stages: pre-dawn, morning and evening. Pre-dawn twilight ends around an hour before sunrise; morning twilight starts just after sunrise and lasts until shortly before sunset; and evening twilight ends just after sunset.
Pre-dawn and evening twilights are very short, since it isn't light enough to see with. Morning twilight is longest, usually about an hour.
"Sunset" is the inverse. Technically, "dusk" refers to the time of twilight that occurs between full darkness and daybreak (or sunset). In everyday parlance, "dawn" refers to the morning, but "dusk" solely refers to the evening twilight. So, the opposite of dusk is not dawn, but sunrise.
The word "dawn" comes from the Old English word dæg, which means "day." So, the opposite of dusk is really the opposite of night, which is day. Dus can also mean "twilight," so the opposite of dusk is actually sunrise.
Dusk ends when the sun drops below the horizon. When this happens, you can no longer see it. It has set forever. That is why it is called the opposite of dawn, because it is once the sun rises, that it becomes visible again. The term "morning twilight" or "evening twilight" is used to describe those times just after dawn or before dusk, when you can still see some color in the sky. But eventually, even that disappears. Then it is completely dark.
Dusk is usually defined as the moment immediately following dawn when only the rising or setting sun is visible over a clear horizon. However, there are exceptions to this rule. For example, when clouds block out part of the sun light then dusk will not occur until those clouds lift.
The period between day and night when there is light outdoors but the sun is below the horizon is known as twilight. At first, sunlight reaches the ground at around noon during the summer solstice, but by late summer it is no longer over the horizon. By early fall, the days are getting shorter again and by winter they have gone back down into darkness.
Twilight ends when the sun rises beyond the horizon. The time when this occurs is called dawn, and it can be several hours after full daylight. During spring and fall, when the days are longest, there may be two dawns in an hour; during winter, when the days are shortest, there may be three or four.
At some times of year, you can see clouds moving across the face of the moon - this is called a lunar eclipse. As the earth moves between the moon and the sun, only certain parts of its surface are illuminated. These areas include the part facing the earth, which appears bright because of reflection from the sunlit side; and the part facing away from us, which is dark because we are looking through the thick atmosphere onto the unlit side.
Lunar eclipses are visible on half of Earth.