If, during the progress of a total [solar] eclipse, the gradually
diminishing crescent of the sun is watched, nothing remarkable is seen until
very near the moment of its total disappearance. But, as the last ray of
sunlight vanishes, a scene of unexampled beauty, grandeur, and
impressiveness breaks upon the view. The globe of the moon, black as ink, is
seen as if it were hanging in mid-air, surrounded by a crown of soft,
silvery light, like that which the old painters used to depict around the
heads of saints. Besides this "corona", tongues of rose-colored flame of
the most fantastic forms shoot out from various points around the edge of
the lunar disk. Of these two appearances, the corona was noticed at least as
far back as the time of Kepler; indeed, it was not possible for a total
eclipse to happen without the spectators seeing it. But it is only within a
century that the attention of astronomers has been directed to the
rose-colored flames, although an observation of them was recorded in the
Philosophical Transactions nearly two centuries ago. They are known by the
several names of "flames," "prominences," and "protruberances."
— Simon Newcomb. 1878. Popular Astronomy. New York: Harper & Brothers. p. 252
On 2017 August 21, a total solar eclipse will be visible to fortunate observers in the United States along a narrow band, approximately 73 miles (118 km) wide, that crosses twelve states from Oregon to South Carolina.
- Calculate local circumstances
- View US map and circumstances
- View global map and circumstances (USNO Eclipse Portal)
- View global visibility map (The Astronomical Almanac)
- View circumstances at Shawnee National Forest, Illinois, site of maximum eclipse
- General eclipse resources
- Notes on local circumstances
- Eclipse definitions
Calculate local circumstances
Major U.S. cities in the path of totality: Casper, WY; Kansas City, KS; Jefferson City, MO; Kansas City, MO; Lincoln, NE; Salem, OR; Columbia, SC; Greenville, SC; Nashville, TN, St. Louis, MO; Charleston, SC
Form A - U.S. Cities or Towns
Form B - Locations Worldwide
For other eclipses, try our Solar Eclipse Computer. Times are given in UT1; for help converting them to local time, see U.S. Time Zones. Notes on the local eclipse circumstances are located at the bottom of this page.
View US map and circumstances
Her Majesty's Nautical Almanac Office (HMNAO), United Kingdom Hydrographic Office provides a 2017 total solar eclipse map. The map contains detailed information about the eclipse for selected US cities, including local circumstances, animations, and diagrams. Please click on the image to visit the full map.
View global map and circumstances (USNO Eclipse Portal)
The USNO Eclipse Portal provides diagrams and animations showing the global circumstances and local circumstances at selected locations. The Portal is a joint effort with Her Majesty's Nautical Almanac Office (HMNAO), United Kingdom Hydrographic Office.
Times are given in UT; for help converting them to local time, see World Time Zone Map.
View global visibility map (The Astronomical Almanac)
For visibility maps of other eclipses, see Eclipses of the Sun and Moon.
View circumstances at Shawnee National Forest, Illinois, site of maximum eclipse
Local circumstance diagram for the location of maximum duration of totality (from HMNAO).
General eclipse resources
Solar Eclipse Viewing Safety
Provides information about how to safely watch the eclipse
- Eclipses of the Sun and Moon
Solar and lunar eclipse visibility maps for recent and upcoming events
- Solar Eclipse Computer
Computes local circumstances for selected solar eclipses at any given location
- Lunar Eclipse Computer
Computes circumstances for selected lunar eclipses at any given location
- USNO Eclipse Portal
Provides diagrams and animations of global and select local circumstances for solar and lunar eclipses, 1501–2100
- References on Eclipses
Provides a representative survey of the available literature
The table of local circumstances gives the UT1 time of each eclipse "event" that is visible from the location. The altitude and azimuth of the Sun at each of the events is given as well. The azimuth is reckoned eastward from North. The altitude is corrected for refraction assuming standard atmospheric conditions.
The computation of Eclipse Local Circumstances is started by iteratively computing topocentric positions of the Sun and Moon to find the time of Maximum Eclipse. Another series of position computations is performed going backwards and forwards from the time of Maximum Eclipse to find the times of contacts. The solar and lunar angular diameters are calculated at each position using radius values from DE405 (Sun 696000km; Moon 1737.4 km) to determine if contact conditions have occurred. Lunar limb profiles and center of mass/center of figure corrections are not used.
After contact times have been computed, a check is made to determine if Sunrise and/or Sunset occurred during the course of the eclipse. If so, the time of Sunrise and/or Sunset is computed.
The body of the table contains the time of each contact point, the Sun's topocentric position at that time, and its Position and Vertex Angles. The time of sunrise or sunset is also noted in the table if it occurs during the eclipse. The summary at the bottom contains the Duration, Magnitude, and Obscuration.
The Position Angle of a given contact point on the solar limb is measured eastward (counterclockwise) around the solar limb, from the point on the Sun that is farthest north.
Vertex Angle is similar to Position Angle, except that it is measured from the point on the Sun that has the highest local altitude.
Duration is the amount of time from the beginning of the eclipse to the end.
Duration of Totality is the amount of time from the beginning of the central phase eclipse to the end of the central phase. For an annular solar eclipse, it will read Duration of Annularity .
Magnitude of the eclipse is the fraction of the apparent diameter of the solar disk covered by the Moon at the time of greatest phase, expressed in units of solar diameter.
Additional eclipse definitions
- the angular distance of a celestial body above or below the horizon, measured along the great circle passing through the body and the zenith. Altitude is 90° minus the zenith distance.
- the angular distance measured eastward along the horizon from a specified reference point (usually north). Azimuth is measured to the point where the great circle determining the altitude of an object meets the horizon.
- the difference between Terrestrial Time (TT) and Universal Time (UT): ΔT=TT − UT1.
- the obscuration of a celestial body caused by its passage through the shadow cast by another body.
- eclipse, solar:
- actually an occultation of the Sun by the Moon in which the Earth passes through the shadow cast by the Moon. It may be total (observer in the Moon's umbra), partial (observer in the Moon's penumbra), annular, or annular-total.
- the obscuration of one celestial body by another of greater apparent diameter; especially the passage of the Moon in front of a star or planet, or the disappearance of a satellite behind the disk of its primary. If the primary source of illumination of a reflecting body is cut off by the occultation, the phenomenon is also called an eclipse. The occultation of the Sun by the Moon is a solar eclipse.
- 1. The portion of a shadow in which light from an extended source is partially but not completely cut off by an intervening body. 2. The area of partial shadow surrounding the umbra.
- the portion of a shadow cone in which none of the light from an extended light source (ignoring refraction) can be observed.