Why are there three twilights? Science answers!

Have you ever seen twilight? I’m not talking about the teenage vampire series that became famous a few years ago; It is actually an atmospheric phenomenon that occurs between sunset and complete darkness at night. It is possible to watch a visual feast of various colors, including orange, yellow, pink and purple tones, in the afternoons during the event.

In other words, twilight occurs at the transition of day and night, but it does not occur in a single way.. There are three different phases of twilight and each has different characteristics. For example, not all events occur between the afternoon and early evening; They may also start a little after dawn.

“Twilight occurs when the Earth’s upper atmosphere scatters and refracts sunlight, illuminating the lower atmosphere. Various atmospheric phenomena and colors can be observed during dusk. Astronomers define the three phases of twilight based on the Sun’s distance below the horizon. Morning twilight is often called dawn, while afternoon twilight is known as twilight,” explains the Time and Date website.

Even though it’s every day, It is important to emphasize that twilight is not always the same, as the appearance of twilight can vary depending on different factors such as time of year, weather conditions and geographical location. For example, morning twilight is completely different from afternoon twilight.

To further explain the differences between the three twilights, TecMundo gathered information from scientists and experts in the field. Check out!

Three types of twilight

This phenomenon occurs when the Sun is below the horizon, but its light can still illuminate the atmosphere and present a visual spectacle in the sky. Twilight is also not the same in different parts of the world, after all, in higher latitudes light can linger much longer after sunset. Therefore, the most common twilight is defined when the Sun is about 6 degrees below the horizon.

“Twilight, in its most general sense, is the period that occurs before sunrise and after sunset, when the atmosphere is partially illuminated by the sun, neither completely dark nor fully illuminated. However, there are three categories of twilight defined by the sun’s distance below the horizon.” This is explained by the United States National Oceanic and Atmospheric Administration (NOAA).

twilight civilization

Civil twilight, also known as civil twilight, is the first and last twilight of the day. It occurs at dawn and late afternoon, when the Sun is less than 6 degrees below the horizon in both periods. At this stage, The lighting of the phenomenon is capable of comprehensively illuminating the area and provides sufficient light, eliminating the need for artificial lighting of any kind.

Civil twilight is considered the most illuminated format of all twilight types, as the illumination is sufficient to not obstruct visibility. It is not surprising that many countries use the classification for laws related to the aviation industry.

“Under these conditions, without fog or other restrictions, the brightest stars and planets can be seen, objects on the horizon and the ground can be discerned, and in most cases artificial lighting is unnecessary,” explains NOAA.

Sea Twilight

Marine twilight usually occurs when the Sun is 6 to 12 degrees below the horizon. To contain, The term ‘nautical’ was used because sailors took readings and determined their positions using stars that remained visible even without the illumination of the Moon. Also in the US, the military uses the concept of ‘maritime twilight’ to describe periods in tactical operations.

It is defined by NOAA as follows: “In the absence of fog or other obstructions, the outlines of terrestrial objects may still be discernible, but without artificial illumination detailed external activity is likely restricted.”

Astronomical Twilight

Astronomical twilight occurs when the geometric center of the Sun is approximately 12 to 18 degrees below the horizon. In this case, the sky becomes so dim that only light sources from stars and planets can be observed with the naked eye. The duration of such twilight depends on the latitude at which the observation is made; for example, higher latitudes have a longer duration.

“Point light sources, such as stars and planets, can be easily studied by astronomers under astronomical twilight. But diffuse light sources, such as galaxies, nebulae and globular clusters, need to be observed under a completely dark sky, again when the Sun is more than 18 degrees below the horizon,” he explains. NOAA about astronomical twilight.

Did you like the content? Stay up to date with more curiosities like this at TecMundo. If you wish, have the opportunity to understand how a day would last 65 hours if the Sun did not affect the Earth’s rotation.