Returns an array with information about sunset/sunrise and twilight begin/end

Description

date_sun_info(int $timestamp, float $latitude, float $longitude): array

Parameters

timestamp: Unix timestamp.
latitude: Latitude in degrees.
longitude: Longitude in degrees.

Return Values

Returns array on success or false on failure. The structure of the array is detailed in the following list:

sunrise: The timestamp of the sunrise (zenith angle = 90°35').
sunset: The timestamp of the sunset (zenith angle = 90°35').
transit: The timestamp when the sun is at its zenith, i.e. has reached its topmost point.
civil_twilight_begin: The start of the civil dawn (zenith angle = 96°). It ends at sunrise.
civil_twilight_end: The end of the civil dusk (zenith angle = 96°). It starts at sunset.
nautical_twilight_begin: The start of the nautical dawn (zenith angle = 102°). It ends at civil_twilight_begin.
nautical_twilight_end: The end of the nautical dusk (zenith angle = 102°). It starts at civil_twilight_end.
astronomical_twilight_begin: The start of the astronomical dawn (zenith angle = 108°). It ends at nautical_twilight_begin.
astronomical_twilight_end: The end of the astronomical dusk (zenith angle = 108°). It starts at nautical_twilight_end.

The values of the array elements are either UNIX timestamps, false if the sun is below the respective zenith for the whole day, or true if the sun is above the respective zenith for the whole day.

Changelog

Version	Description
7.2.0	The calculation was fixed with regards to local midnight instead of local noon, which changes the results slightly.

Examples

Example #1 A date_sun_info() example

<?php
$sun_info = date_sun_info(strtotime("2006-12-12"), 31.7667, 35.2333);
foreach ($sun_info as $key => $val) {
    echo "$key: " . date("H:i:s", $val) . "\n";
}
?>

The above example will output:

sunrise: 05:52:11
sunset: 15:41:21
transit: 10:46:46
civil_twilight_begin: 05:24:08
civil_twilight_end: 16:09:24
nautical_twilight_begin: 04:52:25
nautical_twilight_end: 16:41:06
astronomical_twilight_begin: 04:21:32
astronomical_twilight_end: 17:12:00

Example #2 Polar night, with some processing

<?php
$tz = new \DateTimeZone('America/Anchorage');

$si = date_sun_info(strtotime("2022-12-21"), 70.21, -148.51);
foreach ($si as $key => $value) {
    echo
        match ($value) {
            true => 'always',
            false => 'never',
            default => date_create("@{$value}")->setTimeZone($tz)->format( 'H:i:s T' ),
        },
        ": {$key}",
        "\n";
}
?>

The above example will output:

never: sunrise
never: sunset
12:52:18 AKST: transit
10:53:19 AKST: civil_twilight_begin
14:51:17 AKST: civil_twilight_end
09:01:47 AKST: nautical_twilight_begin
16:42:48 AKST: nautical_twilight_end
07:40:47 AKST: astronomical_twilight_begin
18:03:49 AKST: astronomical_twilight_end

Example #3 Midnight sun (Tromsø, Norway)

<?php
$si = date_sun_info(strtotime("2022-06-26"), 69.68, 18.94);
print_r($si);
?>

The above example will output:

Array
(
    [sunrise] => 1
    [sunset] => 1
    [transit] => 1656240426
    [civil_twilight_begin] => 1
    [civil_twilight_end] => 1
    [nautical_twilight_begin] => 1
    [nautical_twilight_end] => 1
    [astronomical_twilight_begin] => 1
    [astronomical_twilight_end] => 1
)

Example #4 Calculating length of day (Kyiv)

<?php
$si = date_sun_info(strtotime('2022-08-26'), 50.45, 30.52);
$diff = $si['sunset'] - $si['sunrise'];
echo "Length of day: ",
    floor($diff / 3600), "h ",
    floor(($diff % 3600) / 60), "s\n";
?>

The above example will output:

Length of day: 13h 56s