Sunlight‑Based Terms for Times of Day

The transition from day to night (and vice versa) is divided into several phases based on the Sun's position relative to the horizon. While we often use words like "dusk" and "twilight" interchangeably in casual conversation, they have precise astronomical and poetic meanings.

Night - The Sun is more than 18° below the horizon; no scattered sunlight reaches the lower atmosphere.

Astronomical Twilight - The Sun is 18° to 12° below the horizon.

• Astronomical dawn — the moment the Sun reaches 18° below the horizon in the morning.

• Astronomical twilight (morning) — faint light appears, but most people still perceive full darkness.

• Astronomical twilight (evening) — faint light persists after sunset.

• Astronomical dusk — the moment the Sun sinks past 18° below the horizon in the evening.

Nautical Twilight - The Sun is 12° to 6° below the horizon.

• Nautical dawn — Sun reaches 12° below the horizon; horizon becomes visible.

• Nautical twilight (morning) — sailors historically used this light to see both stars and the horizon.

• Nautical twilight (evening) — horizon still visible but dim.

• Nautical dusk — Sun reaches 12° below the horizon; horizon visibility fades.

Civil Twilight - The Sun is 6° below the horizon up to the horizon.

• Civil dawn — Sun is 6° below the horizon; enough light for many outdoor activities.

• Civil twilight (morning) — brightening sky before sunrise.

• Civil twilight (evening) — lingering light after sunset.

• Civil dusk — Sun reaches 6° below the horizon; artificial light usually becomes necessary.

Sunrise & Sunset - The Sun crosses the horizon.

• Sunrise — the upper limb of the Sun appears.

• Sunset — the upper limb of the Sun disappears.

Daylight - The Sun is above the horizon.

• Early morning — shortly after sunrise.

• Morning — increasing sunlight.

• Midday / Noon — Sun at its highest point.

• Afternoon — declining but strong sunlight.

• Late afternoon — warm, angled light.

• Golden hour — warm, low-angle sunlight shortly after sunrise or before sunset.

• Blue hour — cool-toned light just before sunrise or after sunset, overlapping civil twilight.

Dawn & Dusk are umbrella terms.

• Dawn — the entire transition from night to sunrise (all twilight phases).

• Dusk — the entire transition from sunset to night (all twilight phases).

Deep Night occurs after astronomical dusk and before astronomical dawn.

• Night — full darkness.

• Midnight — the midpoint of the night (civil time, not astronomical).

Upper and Lower Case

Upper and lower cases

I love this very literal word origin story. The terms uppercase and lowercase that we associate with the letters of the alphabet evolved directly from the physical storage system used by typesetters in the era of the movable-type printing press.

We go back to the days of Johannes Gutenberg in the 15th century. The movable type system in early printing meant that every single letter, numeral, and punctuation mark was cast as an individual block of metal, called a sort.

To compose a page of text, a typesetter (or compositor) had to pick out each sort one by one and arrange them backward in a frame.

To keep the hundreds of different sorts organized and easily accessible, printers stored them in compartmentalized wooden trays called type cases. Traditionally, the typesetter would use a pair of cases, which were set up on a working stand, often angled and stacked. The upper case, which was set above and behind the lower one, held the capital letters. Capital letters (which were also known as majuscule letters) are used far less frequently in English text, so they could be stored slightly further away.

The lower case, positioned below and closer to the typesetter, held the small letters (also known as minuscule letters) that make up the vast majority of any given text.

The arrangement of the letter compartments within the lower case was based on letter frequency. The largest compartments, and those closest to the typesetter, were for the most common letters, like 'e', 't', 'a', and 'o', saving the typesetter time and effort.

The terms became standardized and filtered out from the printing trade into general language around the 18th century, thankfully replacing the older, more technical terms of majuscule and minuscule.

Noon and Midnight

“Noon” and “midnight” are just two of our designations of times of the day. Both mark the point when an analog clock starts another 12-hour cycle. But the word “noon” took a little bit of a journey around the clock before arriving at its current location.

The root of the word “noon” is the Latin nonus, meaning “ninth,” which became nōn in Old English and Middle English. The word marked the ninth hour after sunrise. This made “noon” a bit of a moving target, but a 6 a.m. sunrise, for instance, would put noon around 3 p.m.

It may have been fasting monks that caused noon to shift earlier in the day. The ninth hour is significant in Christian liturgy as time set aside for prayer, known as nones, and it was particularly important in early monastic traditions. Because monks were often required to fast until then, one prevailing theory as to why the ninth-hour prayer started drifting earlier is that people were getting hungry. The Roman Catholic canonical hour of nones remained at 3 p.m., but by the 14th century, “noon” referred to a new time of day, when the sun was highest in the sky.