JavaScript Solar Eclipse Explorer for the United States

Fred Espenak

Instructions

The JavaScript Solar Eclipse Explorer can compute the local circumstances for every solar eclipse visible from a city for any century from -1499 to 3000 (1500 BCE to 3000 CE). Just follow these instructions:

Section 1 - Select a city from the drop-down menu or manually enter the geographic coordinates and time zone.
Section 2 - Choose the desired century by clicking the button.
Section 3 - A table will be generated giving the local circumstances for every eclipse visible for the selected city and century.

All times are displayed in local time using the value from the Time Zone field in Section 1 (you must add 1 hour if Daylight Saving Time is in effect).

A time followed by "(r)" means the event is already in progress at sunrise. Similarly, a time followed by "(s)" means the event is still in progress at sunset. In such cases, the times and circumstances given are for sunrise or sunset, respectively. The times of sunrise and sunset are calculated when the Sun's lower limb touches the horizon. For more information about the local circumstances table, see Key to JavascriptSolar Eclipse Explorer.

The JavaScript Lunar Eclipse Explorer is a similar web tool for determining the visibility of lunar eclipses from any city.

Section 1: City Coordinates

Section 2: Century Selection

Choose a century* (click on button):

* Negative years are equivalent to the year BC minus 1 year (See: Dating Conventions ).

Section 3: Eclipse Predictions

A time followed by "(r)" means the event is already in progress at sunrise, while a time followed by "(s)" means the event is still in progress at sunset. In such cases, the times and circumstances given are for sunrise or sunset, respectively.

Negative years are equivalent to the year BC minus 1 year (See: Dating Conventions ).

Acknowledgments

The Eclipse Explorer is based on the JavaScript Solar Eclipse Calculator created by Chris O'Byrne and Stephen McCann. The original calculator predicts the local circumstances for any single eclipse over the period 1970 to 2039 for a geographic position supplied by the user.

The Javascript Solar Eclipse Explorer presented here features drop-down menus for city coordinates and buttons to select any century from -1499 to 3000 (1500 BCE to 3000 CE). It can be used to explore the frequencey and circumstances of all solar eclipses visible from any location on Earth. The Eclipse Explorer was developed by Chris O'Byrne and Fred Espenak.

The Besselian elements and values of ΔT used in Solar Eclipse Explorer are the same as those used by the Five Millennium Canon of Solar Eclipses: -1999 to +3000. For the purposes of calculating eclipse circumstances from a given place, the growing uncertainty in the value of ΔT and the corresponding longitude become unacceptably large outside time period of -1499 to 3000 (1500 BCE to 3000 CE).