Frequently Asked Questions

This is a solar clock. It measures the time of the day and night according to the method used by the ancient Romans. It is upon this scaffolding of time that the liturgical practices of Christian monasteries were structured.

Of course, the clock dial itself is an anachronism – the Romans never used such a device. Like many other ancient civilisations, they measured the time of day using the position of the sun. Ideally this was done using a sundial, but in the absence of such a device, by estimating the position of the sun in the sky. The time of night was measured by noting the positions of known constellations relative to the polar star based on the particular time of year.

The ancient Romans divided the daylight into twelve equal parts, named "hours", and the darkness into four equal parts, named "vigils" or "watches". Because the actual amount of daylight and darkness varies through the year, the exact length of an hour or a watch depends on the time of year and your actual latitude.

The nearer to mid-Summer you are, the longer the duration of the hours and the shorter the duration of the watches. Conversely, the nearer to mid-Winter you are, the shorter the duration of the hours and the longer the duration of the watches.

The higher your latitude, that is, the nearer you are to the North or South Pole, the greater the variance in hour and watch duration you will experience through the year. Conversely, if you are near the equator you will experience very little variance in hour and watch duration through the year.

This specific method of measuring time was developed by the Romans for their military.

The Roman military divisions of day and night offered a simple and orderly way to structure time. Early Christian monks—particularly in Egypt, Palestine, and eventually the West—saw in this model an ideal framework for regulating communal prayer, work, and rest.

What was once a tool of military discipline was transformed into a tool of sanctification. The hours became markers for divine office and contemplation, not for guard changes or watch duties. In this way, monasticism baptised a practical Roman system and turned it toward the service of God.

Mechanical time is convenient, but it is detached from the natural rhythms of light and darkness that govern our daily lives. The Roman system reflects the real progression of the sun through the sky, inviting us to become more attentive to the natural order of time and to structure our lives accordingly.

For centuries, monasteries and communities shaped their work, prayer, and rest according to this rhythm. The reintroduction of solar time invites a deeper harmony with the day as God created it—not by hourly precision, but by sacred proportion.

The canonical hours of prayer—such as Prime, Terce, Sext, and None—were not originally tied to fixed clock times like 6am or 12pm. They were intended to correspond with specific moments of the sun’s journey across the sky. Roman Solar Time restores this alignment, helping users experience the divine hours in their proper temporal context.

This is not just about accuracy—it is about sanctifying time. Living by the sun restores a sense of sacred rhythm to daily life, whether or not one prays the breviary.

The app presents time according to the Roman division of the day into twelve hours and the night into four vigils. It helps users visualise the natural rhythm of light and darkness, not to replace civil time, but to recover an older, more proportionate understanding of the day’s passage.

Civil time is the fixed time system used in modern life. It divides the day into twenty-four equal hours and is standardised across time zones. Roman time, by contrast, divides the daylight into twelve variable hours and the night into four vigils, based on actual sunrise and sunset. This app presents solar events in civil time to help the user relate ancient rhythms to modern schedules.

The Solar Dial is the central visual feature of the app. It shows the unequal hours of daylight and vigils of night as proportional coloured segments that shift throughout the year. It gives an at-a-glance sense of where you are in the natural day.

The Bottom Info is a block of explanatory text beneath the dial. It displays the name and duration of the current hour or vigil, and an anticipatory countdown to the next notable moment.

The Day View is opened by tapping the sun icon at the top of the screen. It presents the key solar events—sunrise, solar midday, sunset, and solar midnight—as well as the start times of the canonical hours and each vigil. These are displayed in civil time for convenience.

The temporal boundaries of the vigils are denoted by particular names: sunset marks the beginning of the First Watch; a time called "First Awakening" marks the transition between the First and Second watches, so called because, when people used to lay down to bed at sunset, they would often break their sleep into two parts, awakening at this time; True Solar Midnight, the midpoint between sunset and sunrise, is also the transition point between the Second and Third watches; cockcrow marks the transition between the Third and Fourth watches, so called because this was frequently close to first time during the night when a rooster would be heard to crow; and finally sunrise marks the end of the Fourth Watch and the start of the First Hour (Prime).

The Resource Menu contains educational material that explores Roman timekeeping, the history of the canonical hours, and how these patterns shaped Christian prayer, work, and rest. It is designed to support deeper engagement at your own pace.

In the release version of the app, the Settings Menu allows you to enable solar minutes and seconds—if you’ve unlocked them via in-app purchase. It also provides access to the in-app purchase itself, and includes an option for submitting a bug report.

Not at all. This app is not prescriptive. Some users may simply enjoy observing the rhythm of light and darkness. Others may choose to mark one or two solar hours in their day, or align a daily ritual with sunrise or midday. Still others may gradually shape their lifestyle around this natural rhythm. The app offers a framework—but how you respond to it is entirely your own.

The solar dial is a visual representation of the natural day, as divided by the Romans: twelve segments for the hours of daylight and four for the vigils of the night. Unlike mechanical clocks, which divide the day evenly regardless of season, this dial stretches or compresses each segment to reflect the true proportion of light and darkness at your location on this particular day.

The dial is anchored to True Solar Midday, which always appears at the top. This is the exact midpoint between sunrise and sunset—not 12:00pm on your civil clock. The Romans oriented their time around the sun’s real position in the sky, and the app preserves this structure. Noon may occasionally coincide with solar midday, but usually it does not.

Each segment represents a solar hour or vigil. The twelve daytime segments are divided into canonical and non-canonical horae (hours), using distinct colours to help distinguish their character. The four night segments represent the Roman vigilae (vigils or watches). The colour palette draws inspiration from medieval astronomical clocks, visually reinforcing the sacred order of time.

The labels number each hour or vigil in Roman Numerals. Canonical hours—Prime (I), Terce (III), Sext (VI), and None (IX)—are specifically linked to Christian prayer and the life of Christ. The labels remain upright relative to solar midday, providing a fixed reference even as the dial expands and compresses with the seasons.

Radial lines mark the four cardinal solar events: sunrise, solar midday, sunset, and solar midnight. They divide the dial into four unequal quadrants. The daylight quadrants each contains six segments; the nighttime quadrants are shorter, each containing two vigils. While the quadrants are not radially symmetrical, they are bilaterally symmetrical—reflecting the natural balance of morning and evening, day and night, rather than equal angles on a compass.

Because the amount of daylight and darkness varies with the seasons. The Romans divided the daylight into twelve equal hours and the darkness into four equal watches—regardless of their actual durations. As a result, solar hours become longer in summer and shorter in winter. The vigils do the opposite: they become shorter in summer and longer in winter. The app reflects this visually, restoring an ancient awareness of seasonal time.

It is. The hour hand inscribes the dial at a constant pace, steadily completing one full revolution from one solar midday to the next. What changes is the size of the hour and vigil segments it passes through. In summer, the daylight hours are broader; in winter, narrower. The hand’s speed does not change, but the geometry of its journey does.

Because this is how the Romans structured the day: twelve daylight horae and four nighttime vigilae.

The daytime hours were intended for marking specific times during the day, especially as people needed (relatively) greater precision for coordinating work, prayer, and activity.

Nighttime required less division, as most people slept. The four watches were used mainly to measure the passage of night and to organise literal military guard shifts—hence the term “watch.” Their practical purpose did not require twelvefold division. This is why the night was treated differently from the day, and why the app follows that ancient pattern.

Canonical hours are those historically marked by prayer—Prime, Terce, Sext, and None. These moments divide the daylight into sacred intervals recalling Christ’s Passion and the discipline of monastic life. Terce marked Christ’s condemnation and was traditionally the hour after which markets opened. None marked His death. These sacred hours framed the working day, with trade typically concluding at the end of the Eleventh Hour. This is the origin of both the “nine to five” schedule and the expression “at the eleventh hour.”

Vespers and Compline, while not fixed to precise solar divisions, were also part of the daily rhythm of prayer. Vespers was traditionally prayed as the light began to fade, before the evening meal. Compline followed as a quiet stocktake of the day, but usually before true nightfall. In this app, we associate Vespers with the Eleventh Hour and Compline with the Twelfth Hour to honour their natural placement toward the day’s end but before nightfallRe-out.

The remaining hours—Secunda, Quarta, Septima, and others—complete the twelvefold division of daylight. Though not canonically observed, they preserve the structure of the Roman day and allow a full visual representation of the solar cycle.

Matins and Lauds were, traditionally, associated with the four nighttime watches. Matins was historically divided into three nocturnes, each mapped to the first three watches. Lauds, which was associated with cockcrow, was traditionally mapped to the Fourth Watch, and was often prayed between cockcrow and sunrise in observant communities. More frequently, though, Matins and Lauds were combined into a single prayer that was prayed soon after sunset (during the First Watch) or anticipated before sunset by many, less observant, communities.

There is no difference. In reference to solar time, the terms vigil and watch are synonymous, and are used interchangeably throughout this website and on the app.