date_sunset

Returns time of sunset for a given day and location (PHP 5)
mixed date_sunset ( int timestamp [, int format [, float latitude [, float longitude [, float zenith [, float gmt_offset]]]]] )

date_sunset() returns the sunset time for a given day (specified as a timestamp) and location.

Parameters

timestamp

The timestamp of the day from which the sunset time is taken.

format

Table 41. `format` constants

constant	description	example
SUNFUNCS_RET_STRING	returns the result as string	16:46
SUNFUNCS_RET_DOUBLE	returns the result as float	16.78243132
SUNFUNCS_RET_TIMESTAMP	returns the result as integer (timestamp)	1095034606

latitude

Defaults to North, pass in a negative value for South. See also: date.default_latitude

longitude

Defaults to East, pass in a negative value for West. See also: date.default_longitude

zenith

Default: date.sunrise_zenith

gmtoffset

Specified in hours.

Errors/Exceptions

Every call to a date/time function will generate a E_NOTICE if the time zone is not valid, and/or a E_STRICT message if using the system settings or the TZ environment variable. See also date_default_timezone_set()

ChangeLog

Version	Description
5.1.0	Now issues the `E_STRICT` and `E_NOTICE` time zone errors.

Return Values

Returns the sunset time in a specified format on success, or FALSE on failure.

Examples

Example 444. date_sunset() example

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<?php

/* calculate the sunset time for Lisbon, Portugal

Latitude: 38.4 North

Longitude: 9 West

Zenith ~= 90

offset: +1 GMT

*/

echo date("D M d Y"). ', sunset time : ' .date_sunset(time(), SUNFUNCS_RET_STRING, 38.4, -9, 90, 1);

?>

The above example will output something similar to:

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Mon Dec 20 2004, sunset time : 18:13

See Also

date_sunrise()

Code Examples / Notes » date_sunset

I use an IP to location database to determine the visitor's approximate latitude and longitude and then serve them a day or night color scheme based on whether it is before civil dawn or dusk. I've had problems when not specifying the timezone, specifically a 1 hour error, so I use GMT. <? date_default_timezone_set("GMT"); function scheme() { $sunrise = date_sunrise(time(), SUNFUNCS_RET_DOUBLE, $latitude, $longitude, 96, 0); $sunset = date_sunset(time(), SUNFUNCS_RET_DOUBLE, $latitude, $longitude, 96, 0); $now = date("H") + date("i") / 60 + date("s") / 3600; if ($sunrise < $sunset) if (($now > $sunrise) && ($now < $sunset)) return "day"; else return "night"; else if (($now > $sunrise) || ($now < $sunset)) return "day"; else return "night"; } ?>

A way to use this: <?php // De Bilt, The Netherlands, weather station #06260 $lat = 52.10; // North $long = 5.18; // East $offset = 1; // difference between GMT and local time in hours $zenith=90+50/60; echo " Sunrise: ".date_sunrise(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); echo " Sunset: ".date_sunset(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); $zenith=96; echo " \"Civilian Twilight\" start: ".date_sunrise(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); echo " \"Civilian Twilight\" end: ".date_sunset(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); $zenith=102; echo " \"Nautical Twilight\" start: ".date_sunrise(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); echo " \"Nautical Twilight\" end: ".date_sunset(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); $zenith=108; echo " \"Astronomical Twilight\" start: ".date_sunrise(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); echo " \"Astronomical Twilight\" end: ".date_sunset(time(), SUNFUNCS_RET_STRING, $lat, $long, $zenith, $offset); ?> Thanks to George King. More sources about this topic: http://www.qarlos.free.fr/navegacion/Sextante/formulas.htm http://williams.best.vwh.net/sunrise_sunset_algorithm.htm http://www.kevinboone.com/suntimes.html http://star-www.st-and.ac.uk/~fv/webnotes/chapt12.htm

date_sunset

Returns time of sunset for a given day and location (PHP 5) mixed date_sunset ( int timestamp [, int format [, float latitude [, float longitude [, float zenith [, float gmt_offset]]]]] )