The map shows you where the cities you’ve added to Darkness are located. The city you’re currently viewing is indicated by a little red flag. Other cities are indicated with a red dot.
Turning your iPhone on its side will display a much larger map. This map can be zoomed in and out by pinching.
You can change the date and time shown by tapping the calendar icon on the top right of the screen. Even though the year isn’t shown in the date and time picker, Darkness does allow for setting the date to any year (so if you scroll past Dec 31, 2010, the date will be Jan 1, 2011). The year does appear at the top of the home screen though, so you can use that to judge what year is being shown
Please note: the info shown in Darkness follows the date and time you’ve set, which may not be the current date and time.
Tapping the < and > buttons will cycle through all the cities you have added to Darkness.
Wikipedia’s definition of sunrise matches the definition for Darkness.
“Sunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the (variously defined) point at which the sky begins to lighten, some time before the sun itself appears, ending twilight.” — Wikipedia
“Noon” in Darkness refers to the exact point in time when solar noon occurs.
Wikipedia’s definition of sunset matches the definition for Darkness.
Moonrise is the instant at which the moon first appears over the Earth’s horizon.
Moonset is the instant at which the moon disappears below the Earth’s horizon.
The Current Azimuth is the azimuth for the sun at the currently chosen date and time (which might not be the actual current date and time). Azimuth refers to the angle between due north and the point on the horizon the sun is currently over.
The Current Altitude is the altitude for the sun at the currently chosen date and time (which might not be the actual current date and time). Altitude refers to the vertical angle measured from the horizon to the position of the Sun. It will be a negative value if the sun is below the horizon. Altitude is commonly also called elevation or elevation above the horizon.
Noon Altitude is the altitude the sun will be at solar noon for the currently chosen date (which might not be the actual current date).
Twilight is the position of the Sun (its centre) relative to the horizon. Civil twilight occurs when the sun is less than 6° below the horizon.
Twilight is the position of the Sun (its centre) relative to the horizon. Nautical twilight occurs when the sun is 6° - 12° below the horizon.
Twilight is the position of the Sun (its centre) relative to the horizon. Astronomical twilight occurs when the sun is 12° - 18° below the horizon.
Darkness’s home screen shows a quick reference for the sun’s altitude. If it’s at the very top of the area, the sun is at its highest point in the sky. If it’s near the bottom, sunrise has just past, or sunset is coming soon.