Class: Astronoby::Sun

Inherits:
SolarSystemBody show all
Defined in:
lib/astronoby/bodies/sun.rb

Overview

Represents the Sun. Provides twilight events, equinox/solstice calculations, and equation of time.

Constant Summary collapse

EQUATORIAL_RADIUS = 
Distance.from_meters(695_700_000)
ABSOLUTE_MAGNITUDE = 
-26.74

Constants inherited from SolarSystemBody

Astronoby::SolarSystemBody::EARTH, Astronoby::SolarSystemBody::EARTH_MOON_BARYCENTER, Astronoby::SolarSystemBody::JUPITER_BARYCENTER, Astronoby::SolarSystemBody::MARS_BARYCENTER, Astronoby::SolarSystemBody::MERCURY, Astronoby::SolarSystemBody::MERCURY_BARYCENTER, Astronoby::SolarSystemBody::MOON, Astronoby::SolarSystemBody::NEPTUNE_BARYCENTER, Astronoby::SolarSystemBody::SATURN_BARYCENTER, Astronoby::SolarSystemBody::SOLAR_SYSTEM_BARYCENTER, Astronoby::SolarSystemBody::SUN, Astronoby::SolarSystemBody::URANUS_BARYCENTER, Astronoby::SolarSystemBody::VENUS, Astronoby::SolarSystemBody::VENUS_BARYCENTER

Instance Attribute Summary

Attributes inherited from SolarSystemBody

#ephem, #instant, #orientation

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from SolarSystemBody

#angular_diameter, #apparent, #astrometric, at, #body, compute_geometric, conjunction_events, #constellation, #earth_geometric, #eastern?, #elongation, geometric, #geometric, greatest_elongation_events, #illuminated_fraction, inferior_planet?, #initialize, #mean_of_date, opposition_events, planet?, rise_transit_set_events, superior_planet?, #western?

Methods included from Position

#observed_by

Constructor Details

This class inherits a constructor from Astronoby::SolarSystemBody

Class Method Details

.absolute_magnitude ⇒ Float

Returns absolute magnitude.

Returns:

  • (Float) —

    absolute magnitude



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# File 'lib/astronoby/bodies/sun.rb', line 17

def self.absolute_magnitude
  ABSOLUTE_MAGNITUDE
end

.december_solstice(year, ephem:) ⇒ Time

Returns Time of the December solstice for the given year.

Parameters:

  • year (Integer) —

    Year for which to calculate equinoxes and solstices

  • ephem (::Ephem::SPK) —

    Ephemeris data source

Returns:

  • (Time) —

    Time of the December solstice for the given year.



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# File 'lib/astronoby/bodies/sun.rb', line 71

def self.december_solstice(year, ephem:)
  EquinoxSolstice.december_solstice(year, ephem)
end

.ephemeris_segments(_ephem_source) ⇒ Array<Array>

Returns ephemeris segment identifiers.

Parameters:

  • _ephem_source (Symbol) —

    the ephemeris source type

Returns:

  • (Array<Array>) —

    ephemeris segment identifiers



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# File 'lib/astronoby/bodies/sun.rb', line 12

def self.ephemeris_segments(_ephem_source)
  [[SOLAR_SYSTEM_BARYCENTER, SUN]]
end

.june_solstice(year, ephem:) ⇒ Time

Returns Time of the June solstice for the given year.

Parameters:

  • year (Integer) —

    Year for which to calculate equinoxes and solstices

  • ephem (::Ephem::SPK) —

    Ephemeris data source

Returns:

  • (Time) —

    Time of the June solstice for the given year.



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# File 'lib/astronoby/bodies/sun.rb', line 57

def self.june_solstice(year, ephem:)
  EquinoxSolstice.june_solstice(year, ephem)
end

.march_equinox(year, ephem:) ⇒ Time

Returns Time of the March equinox for the given year.

Parameters:

  • year (Integer) —

    Year for which to calculate equinoxes and solstices

  • ephem (::Ephem::SPK) —

    Ephemeris data source

Returns:

  • (Time) —

    Time of the March equinox for the given year.



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# File 'lib/astronoby/bodies/sun.rb', line 50

def self.march_equinox(year, ephem:)
  EquinoxSolstice.march_equinox(year, ephem)
end

.september_equinox(year, ephem:) ⇒ Time

Returns Time of the September equinox for the given year.

Parameters:

  • year (Integer) —

    Year for which to calculate equinoxes and solstices

  • ephem (::Ephem::SPK) —

    Ephemeris data source

Returns:

  • (Time) —

    Time of the September equinox for the given year.



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# File 'lib/astronoby/bodies/sun.rb', line 64

def self.september_equinox(year, ephem:)
  EquinoxSolstice.september_equinox(year, ephem)
end

.twilight_events(observer:, ephem:, date: nil, start_time: nil, end_time: nil, utc_offset: 0) ⇒ Astronoby::TwilightEvent+

Returns Twilight events for the given date or time range.

Parameters:

  • observer (Astronoby::Observer) —

    Observer for whom to calculate twilight events

  • ephem (::Ephem::SPK) —

    Ephemeris data source

  • date (Date) (defaults to: nil) —

    Date for which to calculate twilight events (optional)

  • start_time (Time) (defaults to: nil) —

    Start time for twilight event calculation (optional)

  • end_time (Time) (defaults to: nil) —

    End time for twilight event calculation (optional)

  • utc_offset (String) (defaults to: 0) —

    UTC offset for the given date (e.g., “+02:00”)

Returns:



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# File 'lib/astronoby/bodies/sun.rb', line 31

def self.twilight_events(
  observer:,
  ephem:,
  date: nil,
  start_time: nil,
  end_time: nil,
  utc_offset: 0
)
  calculator = TwilightCalculator.new(observer: observer, ephem: ephem)
  if date
    calculator.event_on(date, utc_offset: utc_offset)
  else
    calculator.events_between(start_time, end_time)
  end
end

Instance Method Details

#apparent_magnitude ⇒ Float

Source:

Title: Explanatory Supplement to the Astronomical Almanac
Authors: Sean E. Urban and P. Kenneth Seidelmann
Edition: University Science Books
Chapter: 10.3 - Phases and Magnitudes

Apparent magnitude of the body, as seen from Earth.

Returns:

  • (Float) —

    Apparent magnitude of the body.



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# File 'lib/astronoby/bodies/sun.rb', line 82

def apparent_magnitude
  @apparent_magnitude ||=
    self.class.absolute_magnitude + 5 * Math.log10(astrometric.distance.au)
end

#approaching_primary? ⇒ Boolean

Returns always false; the Sun has no primary body.

Returns:

  • (Boolean) —

    always false; the Sun has no primary body



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# File 'lib/astronoby/bodies/sun.rb', line 124

def approaching_primary?
  false
end

#equation_of_time ⇒ Astronoby::Duration

Returns Equation of time.

Returns:



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# File 'lib/astronoby/bodies/sun.rb', line 94

def equation_of_time
  right_ascension = apparent.equatorial.right_ascension
  t = (@instant.julian_date - JulianDate::J2000) / Constants::DAYS_PER_JULIAN_MILLENIA
  l0 = (280.4664567 +
    360_007.6982779 * t +
    0.03032028 * t**2 +
    t**3 / 49_931 -
    t**4 / 15_300 -
    t**5 / 2_000_000) % Constants::DEGREES_PER_CIRCLE
  nutation = Nutation.new(instant: instant).nutation_in_longitude
  obliquity = TrueObliquity.at(@instant)

  seconds = (
    Angle
      .from_degrees(
        l0 -
          Constants::EQUATION_OF_TIME_CONSTANT -
          right_ascension.degrees +
          nutation.degrees * obliquity.cos
      ).hours * Constants::SECONDS_PER_HOUR
  ).round
  Duration.from_seconds(seconds)
end

#phase_angle ⇒ nil

Returns the Sun has no phase angle as seen from Earth.

Returns:

  • (nil) —

    the Sun has no phase angle as seen from Earth



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# File 'lib/astronoby/bodies/sun.rb', line 119

def phase_angle
  nil
end

#receding_from_primary? ⇒ Boolean

Returns always false; the Sun has no primary body.

Returns:

  • (Boolean) —

    always false; the Sun has no primary body



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# File 'lib/astronoby/bodies/sun.rb', line 129

def receding_from_primary?
  false
end