Beyond Sunrise and Sunset: Exploring the Science Behind Civil, Nautical, and Astronomical Twilight

The beauty of sunrise and sunset is a sight to behold, with the sky painted in shades of pink and orange. But what happens before and after these moments? Recently, GBH meteorologist Dave Epstein shared with Morning Edition co-hosts Jeremy Siegel and Paris Alston the science behind this stunning phenomenon.

According to Epstein, civil twilight is his favorite time of the day. It occurs just before sunrise and after sunset when the sun is zero to six degrees below the horizon. During this time, the sky is still light, and the sun is not yet fully visible, creating stunning sunrises and sunsets. Civil twilight provides a perfect opportunity for photographers to capture the beauty of nature at its best.

Nautical twilight takes place when the sun is six to 12 degrees below the horizon and occurs before civil twilight in the morning and after civil twilight in the evening. During this time, animals like deer and coyotes emerge, making it a cautious time for drivers. Nautical twilight also allows for the observation of faint objects like stars that are not visible during other times of day.

Following nautical twilight is astronomical twilight when the sun is between 12 and 18 degrees below the horizon. This period allows for the observation of faint objects like galaxies that are not visible during other times of day. Astronomical twilight can be a great opportunity for stargazing enthusiasts who want to observe celestial objects in their natural state without interference from artificial light pollution.

In summer months such as June, astronomical twilight occurs early and late, resulting in a very short nighttime. In northern regions, night may not start until late in