Returns time of sunset for a given day and location

Description

date_sunset ( int $timestamp [, int $format = SUNFUNCS_RET_STRING [, float $latitude = ini_get("date.default_latitude") [, float $longitude = ini_get("date.default_longitude") [, float $zenith = ini_get("date.sunset_zenith") [, float $gmt_offset = 0 ]]]]] ) : mixed

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

**`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

zenith is the angle between the center of the sun and a line perpendicular to earth's surface. It defaults to date.sunset_zenith

**Common `zenith` angles**
Angle	Description
90°50'	Sunset: the point where the sun becomes invisible.
96°	Civil twilight: conventionally used to signify the end of dusk.
102°	Nautical twilight: the point at which the horizon ends being visible at sea.
108°	Astronomical twilight: the point at which the sun ends being the source of any illumination.

gmtoffset

Specified in hours. The gmtoffset is ignored, if format is SUNFUNCS_RET_TIMESTAMP.

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 or E_WARNING 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. One potential reason for failure is that the sun does not set at all, which happens inside the polar circles for part of the year.

Examples

Example #1 date_sunset() example


<?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:

Mon Dec 20 2004, sunset time : 18:13

Example #2 No sunset


<?php
$solstice = strtotime('2017-12-21');
var_dump(date_sunset($solstice, SUNFUNCS_RET_STRING, 69.245833, -53.537222));
?>

The above example will output:

bool(false)

date_sunset