Class: Astronoby::LunarEclipseCalculator::Geometry

Inherits:
Object
  • Object
show all
Defined in:
lib/astronoby/events/lunar_eclipse_calculator.rb

Overview

Geometry of the Sun, Moon and Earth’s shadow at one instant, in kilometres in the plane perpendicular to the shadow axis at the Moon’s distance.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(axis_distance:, umbra_radius:, penumbra_radius:, gamma:) ⇒ Geometry

Returns a new instance of Geometry.



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 71

def initialize(axis_distance:, umbra_radius:, penumbra_radius:, gamma:)
  @axis_distance = axis_distance
  @umbra_radius = umbra_radius
  @penumbra_radius = penumbra_radius
  @gamma = gamma
  freeze
end

Instance Attribute Details

#axis_distance ⇒ Float (readonly)

Returns distance of the Moon’s centre from the shadow axis (km).

Returns:

  • (Float) —

    distance of the Moon’s centre from the shadow axis (km)



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 60

def axis_distance
  @axis_distance
end

#gamma ⇒ Float (readonly)

Returns signed distance from the shadow axis, in Earth radii.

Returns:

  • (Float) —

    signed distance from the shadow axis, in Earth radii



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 69

def gamma
  @gamma
end

#penumbra_radius ⇒ Float (readonly)

Returns radius of the penumbra at the Moon’s distance (km).

Returns:

  • (Float) —

    radius of the penumbra at the Moon’s distance (km)



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 66

def penumbra_radius
  @penumbra_radius
end

#umbra_radius ⇒ Float (readonly)

Returns radius of the umbra at the Moon’s distance (km).

Returns:

  • (Float) —

    radius of the umbra at the Moon’s distance (km)



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 63

def umbra_radius
  @umbra_radius
end

Instance Method Details

#partial_contact_value ⇒ Object 



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 93

def partial_contact_value
  axis_distance - (umbra_radius + MOON_RADIUS_KM)
end

#penumbral_contact_value ⇒ Object 



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 89

def penumbral_contact_value
  axis_distance - (penumbra_radius + MOON_RADIUS_KM)
end

#penumbral_magnitude ⇒ Object 



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 83

def penumbral_magnitude
  (
    penumbra_radius + MOON_RADIUS_KM - axis_distance
  ) / (2 * MOON_RADIUS_KM)
end

#total_contact_value ⇒ Object 



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 97

def total_contact_value
  axis_distance - (umbra_radius - MOON_RADIUS_KM)
end

#umbral_magnitude ⇒ Object 



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# File 'lib/astronoby/events/lunar_eclipse_calculator.rb', line 79

def umbral_magnitude
  (umbra_radius + MOON_RADIUS_KM - axis_distance) / (2 * MOON_RADIUS_KM)
end