ca.rmen.sunrisesunset

Class SunriseSunset

java.lang.Object

ca.rmen.sunrisesunset.SunriseSunset

public final class SunriseSunset
extends Object

Provides methods to determine the sunrise, sunset, civil twilight, nautical twilight, and astronomical twilight times of a given location, or if it is currently day or night at a given location.
Also provides methods to convert between Gregorian and Julian dates.
The formulas used by this class are from the Wikipedia articles on Julian Day and Sunrise Equation.

Author:

Carmen Alvarez

See Also:

Julian Day on Wikipedia, Sunrise equation on Wikipedia

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SunriseSunset.DayPeriod

Field Summary

Fields

Modifier and Type	Field and Description
static double	SUN_ALTITUDE_ASTRONOMICAL_TWILIGHT The altitude of the sun (solar elevation angle) at the moment of astronomical twilight: -18.0
static double	SUN_ALTITUDE_CIVIL_TWILIGHT The altitude of the sun (solar elevation angle) at the moment of civil twilight: -6.0
static double	SUN_ALTITUDE_NAUTICAL_TWILIGHT The altitude of the sun (solar elevation angle) at the moment of nautical twilight: -12.0
static double	SUN_ALTITUDE_SUNRISE_SUNSET The altitude of the sun (solar elevation angle) at the moment of sunrise or sunset: -0.833

Method Summary

Modifier and Type	Method and Description
static Calendar[]	getAstronomicalTwilight(Calendar day, double latitude, double longitude) Calculate the astronomical twilight time for the given date and given location.
static Calendar[]	getCivilTwilight(Calendar day, double latitude, double longitude) Calculate the civil twilight time for the given date and given location.
static long	getDayLength(Calendar calendar, double latitude, double longitude)
static SunriseSunset.DayPeriod	getDayPeriod(Calendar calendar, double latitude, double longitude)
static Calendar	getGregorianDate(double julianDate) Convert a Julian date to a Gregorian date.
static double	getJulianDate(Calendar gregorianDate) Convert a Gregorian calendar date to a Julian date.
static Calendar[]	getNauticalTwilight(Calendar day, double latitude, double longitude) Calculate the nautical twilight time for the given date and given location.
static Calendar	getSolarNoon(Calendar day, double latitude, double longitude) Calculate the solar noon time for the given date and given location.
static Calendar[]	getSunriseSunset(Calendar day, double latitude, double longitude) Calculate the sunrise and sunset times for the given date and given location.
static Calendar[]	getSunriseSunset(Calendar day, double latitude, double longitude, double sunAltitude) Calculate the sunrise and sunset times for the given date, given location, and sun altitude.
static boolean	isAstronomicalTwilight(Calendar calendar, double latitude, double longitude)
static boolean	isAstronomicalTwilight(double latitude, double longitude)
static boolean	isCivilTwilight(Calendar calendar, double latitude, double longitude)
static boolean	isCivilTwilight(double latitude, double longitude)
static boolean	isDay(Calendar calendar, double latitude, double longitude)
static boolean	isDay(double latitude, double longitude)
static boolean	isNauticalTwilight(Calendar calendar, double latitude, double longitude)
static boolean	isNauticalTwilight(double latitude, double longitude)
static boolean	isNight(Calendar calendar, double latitude, double longitude)
static boolean	isNight(double latitude, double longitude)
static boolean	isTwilight(Calendar calendar, double latitude, double longitude)
static boolean	isTwilight(double latitude, double longitude)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SUN_ALTITUDE_SUNRISE_SUNSET

public static final double SUN_ALTITUDE_SUNRISE_SUNSET

The altitude of the sun (solar elevation angle) at the moment of sunrise or sunset: -0.833

See Also:

Constant Field Values

SUN_ALTITUDE_CIVIL_TWILIGHT

public static final double SUN_ALTITUDE_CIVIL_TWILIGHT

The altitude of the sun (solar elevation angle) at the moment of civil twilight: -6.0

See Also:

Constant Field Values

SUN_ALTITUDE_NAUTICAL_TWILIGHT

public static final double SUN_ALTITUDE_NAUTICAL_TWILIGHT

The altitude of the sun (solar elevation angle) at the moment of nautical twilight: -12.0

See Also:

Constant Field Values

SUN_ALTITUDE_ASTRONOMICAL_TWILIGHT

public static final double SUN_ALTITUDE_ASTRONOMICAL_TWILIGHT

The altitude of the sun (solar elevation angle) at the moment of astronomical twilight: -18.0

See Also:

Constant Field Values

Method Detail

getJulianDate

public static double getJulianDate(Calendar gregorianDate)

Convert a Gregorian calendar date to a Julian date. Accuracy is to the second.
This is based on the Wikipedia article for Julian day.

Parameters:

gregorianDate - Gregorian date in any time zone.

Returns:

the Julian date for the given Gregorian date.

See Also:

Converting to Julian day number on Wikipedia

getGregorianDate

public static Calendar getGregorianDate(double julianDate)

Convert a Julian date to a Gregorian date. The Gregorian date will be in the local time zone. Accuracy is to the second.
This is based on the Wikipedia article for Julian day.

Parameters:

julianDate - The date to convert

Returns:

a Gregorian date in the local time zone.

See Also:

Converting from Julian day to Gregorian date, on Wikipedia

getCivilTwilight

public static Calendar[] getCivilTwilight(Calendar day,
                                          double latitude,
                                          double longitude)

Calculate the civil twilight time for the given date and given location.

Parameters:

day - The day for which to calculate civil twilight

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

a two-element Gregorian Calendar array. The first element is the civil twilight dawn, the second element is the civil twilight dusk. This will return null if there is no civil twilight. (Ex: no twilight in Antarctica in December)

getNauticalTwilight

public static Calendar[] getNauticalTwilight(Calendar day,
                                             double latitude,
                                             double longitude)

Calculate the nautical twilight time for the given date and given location.

Parameters:

day - The day for which to calculate nautical twilight

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

a two-element Gregorian Calendar array. The first element is the nautical twilight dawn, the second element is the nautical twilight dusk. This will return null if there is no nautical twilight. (Ex: no twilight in Antarctica in December)

getAstronomicalTwilight

public static Calendar[] getAstronomicalTwilight(Calendar day,
                                                 double latitude,
                                                 double longitude)

Calculate the astronomical twilight time for the given date and given location.

Parameters:

day - The day for which to calculate astronomical twilight

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

a two-element Gregorian Calendar array. The first element is the astronomical twilight dawn, the second element is the astronomical twilight dusk. This will return null if there is no astronomical twilight. (Ex: no twilight in Antarctica in December)

getSunriseSunset

public static Calendar[] getSunriseSunset(Calendar day,
                                          double latitude,
                                          double longitude)

Calculate the sunrise and sunset times for the given date and given location. This is based on the Wikipedia article on the Sunrise equation.

Parameters:

day - The day for which to calculate sunrise and sunset

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

a two-element Gregorian Calendar array. The first element is the sunrise, the second element is the sunset. This will return null if there is no sunrise or sunset. (Ex: no sunrise in Antarctica in June)

See Also:

Sunrise equation on Wikipedia

getSunriseSunset

public static Calendar[] getSunriseSunset(Calendar day,
                                          double latitude,
                                          double longitude,
                                          double sunAltitude)

Calculate the sunrise and sunset times for the given date, given location, and sun altitude. This is based on the Wikipedia article on the Sunrise equation.

Parameters:

day - The day for which to calculate sunrise and sunset

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

sunAltitude - the angle between the horizon and the center of the sun's disc.

Returns:

a two-element Gregorian Calendar array. The first element is the sunrise, the second element is the sunset. This will return null if there is no sunrise or sunset. (Ex: no sunrise in Antarctica in June)

See Also:

Sunrise equation on Wikipedia

getSolarNoon

public static Calendar getSolarNoon(Calendar day,
                                    double latitude,
                                    double longitude)

Calculate the solar noon time for the given date and given location. This is based on the Wikipedia article on the Sunrise equation.

Parameters:

day - The day for which to calculate sunrise and sunset

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

a Calendar with the time set to solar noon for the given day.

See Also:

Sunrise equation on Wikipedia

isDay

public static boolean isDay(double latitude,
                            double longitude)

Parameters:

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is currently day at the given location. This returns true if the current time at the location is after the sunrise and before the sunset for that location.

isDay

public static boolean isDay(Calendar calendar,
                            double latitude,
                            double longitude)

Parameters:

calendar - a datetime

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is day at the given location and given datetime. This returns true if the given datetime at the location is after the sunrise and before the sunset for that location.

isNight

public static boolean isNight(double latitude,
                              double longitude)

Parameters:

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is night at the given location currently. This returns true if the current time at the location is after the astronomical twilight dusk and before the astronomical twilight dawn for that location.

isNight

public static boolean isNight(Calendar calendar,
                              double latitude,
                              double longitude)

Parameters:

calendar - a datetime

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is night at the given location and datetime. This returns true if the given datetime at the location is after the astronomical twilight dusk and before the astronomical twilight dawn.

isCivilTwilight

public static boolean isCivilTwilight(double latitude,
                                      double longitude)

Parameters:

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is currently civil twilight at the current time at the given location. This returns true if the current time at the location is between sunset and civil twilight dusk or between civil twilight dawn and sunrise.

isCivilTwilight

public static boolean isCivilTwilight(Calendar calendar,
                                      double latitude,
                                      double longitude)

Parameters:

calendar - the datetime for which to determine if it's civil twilight in the given location

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is civil twilight at the given location and the given calendar. This returns true if the given time at the location is between sunset and civil twilight dusk or between civil twilight dawn and sunrise.

isNauticalTwilight

public static boolean isNauticalTwilight(double latitude,
                                         double longitude)

Parameters:

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is currently nautical twilight at the current time at the given location. This returns true if the current time at the location is between civil and nautical twilight dusk or between nautical and civil twilight dawn.

isNauticalTwilight

public static boolean isNauticalTwilight(Calendar calendar,
                                         double latitude,
                                         double longitude)

Parameters:

calendar - the datetime for which to determine if it's nautical twilight in the given location

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is nautical twilight at the given location and the given calendar. This returns true if the given time at the location is between civil and nautical twilight dusk or between nautical and civil twilight dawn.

isAstronomicalTwilight

public static boolean isAstronomicalTwilight(double latitude,
                                             double longitude)

Parameters:

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is currently astronomical twilight at the current time at the given location. This returns true if the current time at the location is between nautical and astronomical twilight dusk or between astronomical and nautical twilight dawn.

isAstronomicalTwilight

public static boolean isAstronomicalTwilight(Calendar calendar,
                                             double latitude,
                                             double longitude)

Parameters:

calendar - the datetime for which to determine if it's astronomical twilight in the given location

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is astronomical twilight at the given location and the given calendar. This returns true if the given time at the location is between nautical and astronomical twilight dusk or between astronomical and nautical twilight dawn.

isTwilight

public static boolean isTwilight(double latitude,
                                 double longitude)

Parameters:

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

true if it is civil, nautical, or astronomical twilight currently at the given location.

isTwilight

public static boolean isTwilight(Calendar calendar,
                                 double latitude,
                                 double longitude)

Parameters:

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

calendar - the given datetime to check for twilight

Returns:

true if at the given location and calendar, it is civil, nautical, or astronomical twilight.

getDayPeriod

public static SunriseSunset.DayPeriod getDayPeriod(Calendar calendar,
                                                   double latitude,
                                                   double longitude)

getDayLength

public static long getDayLength(Calendar calendar,
                                double latitude,
                                double longitude)

Parameters:

calendar - the datetime for which to determine the day length

latitude - the latitude of the location in degrees.

longitude - the longitude of the location in degrees (West is negative)

Returns:

the number of milliseconds between sunrise and sunset.