venuss 0.0.2

Venus celestial simulation crate for the MilkyWay SolarSystem workspace
Documentation 
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pub struct VenusRotation {
    pub angular_velocity_rad_s: f64,
    pub axial_tilt_rad: f64,
}

impl Default for VenusRotation {
    fn default() -> Self {
        Self::new()
    }
}

impl VenusRotation {
    pub fn new() -> Self {
        Self {
            angular_velocity_rad_s: crate::OMEGA_VENUS,
            axial_tilt_rad: crate::AXIAL_TILT_DEG.to_radians(),
        }
    }

    pub fn surface_velocity_at_latitude(&self, latitude_deg: f64) -> f64 {
        let lat = latitude_deg.to_radians();
        self.angular_velocity_rad_s.abs() * crate::VENUS_RADIUS * lat.cos()
    }

    pub fn coriolis_parameter(&self, latitude_deg: f64) -> f64 {
        2.0 * self.angular_velocity_rad_s * latitude_deg.to_radians().sin()
    }

    pub fn moment_of_inertia(&self) -> f64 {
        crate::MOI_FACTOR * crate::VENUS_MASS * crate::VENUS_RADIUS.powi(2)
    }

    pub fn rotational_kinetic_energy(&self) -> f64 {
        0.5 * self.moment_of_inertia() * self.angular_velocity_rad_s * self.angular_velocity_rad_s
    }

    pub fn angular_momentum(&self) -> f64 {
        self.moment_of_inertia() * self.angular_velocity_rad_s
    }

    pub fn precession_rate_rad_per_year(&self) -> f64 {
        2.0 * std::f64::consts::PI / 287_000.0
    }

    pub fn solar_declination(&self, heliocentric_longitude_deg: f64) -> f64 {
        let l = heliocentric_longitude_deg.to_radians();
        (self.axial_tilt_rad.sin() * l.sin()).asin().to_degrees()
    }

    pub fn day_length_hours(&self, latitude_deg: f64, heliocentric_longitude_deg: f64) -> f64 {
        let decl = self
            .solar_declination(heliocentric_longitude_deg)
            .to_radians();
        let lat = latitude_deg.to_radians();
        let cos_h = -(lat.tan() * decl.tan());
        if cos_h <= -1.0 {
            return 24.0;
        }
        if cos_h >= 1.0 {
            return 0.0;
        }
        cos_h.acos().to_degrees() / 180.0 * 24.0
    }
}