Sun Times

For St. Joseph, Minnesota

W 94° 19'; N45° 34'

The below graphs are in Central Standard Time, you'll need to add an hour if Central Daylight Standard Time is in effect. Note that because the Earth's orbit about the Sun is not a whole number of days (e.g., 1 tropical year=365.24220 days) these plots (made for the year 1998) are not exactly valid for any other year. However, differences are small. In particular the day with the latest sunset etc., will move around by a few days (much as the solstice themselves move a bit).


Sunrise and Sunset
are times when the upper edge of the disk of the Sun is on the ideal horizon (assumed to be unobstructed). Because of atmospheric refraction (bending) of light, this occurs when the Sun is totally below the horizon, and depends in part on atmospheric conditions. Under typical sea-level conditions atmospheric refraction amounts to about 34 arcminutes; the average apparent radius of the Sun is about 16 arcminutes. Thus a 50-arcminute geometric depression of the Sun's center is used for these computations.

Nautical Twilight
is defined to end in the evening, when the center of the sun is geometrically 12° below the horizon. At end of nautical twilight, under good atmospheric conditions and in the absence of other illumination, general outlines of ground objects may be distinguishable, but detailed outdoor operations are not possible, and the horizon is indistinct.

Local Noon
is the time when the Sun is on the meridian, i.e., "high noon" when the Sun reaches is maximum altitude. The fact that this is not exactly at noon has to do with our displacement from the center of the time zone, and irregular motion of the Sun (a.k.a, "the equation of time") you might remember from the analemma on your globe.

make your own table

The below form is designed to compute a table (valid for St. Joseph) for a year you select. The calculations are performed by the U.S. Naval Observatory!