apsis

Documentation

Overview

Apsis: Chapter 50, Perigee and apogee of the Moon

Index

• func Apogee(year float64) float64
• func ApogeeParallax(year float64) unit.Angle
• func MeanApogee(year float64) float64
• func MeanPerigee(year float64) float64
• func Perigee(year float64) float64
• func PerigeeParallax(year float64) unit.Angle

Examples

• Apogee
• ApogeeParallax
• MeanApogee

Functions

func Apogee

func Apogee(year float64) float64

Apogee returns the jde of apogee of the Moon nearest the given date. 远地点

Year is a decimal year specifying a date.

Example

// Example 50.a, p. 357.
j := apsis.Apogee(1988.75)
fmt.Printf("JDE = %.4f\n", j)
y, m, d := julian.JDToCalendar(j)
d, f := math.Modf(d)
fmt.Printf("%d %s %d, at %m TD\n", y, time.Month(m), int(d),
	sexa.FmtTime(unit.TimeFromDay(f)))

Output:

JDE = 2447442.3543
1988 October 7, at 20ʰ30ᵐ TD

func ApogeeParallax

func ApogeeParallax(year float64) unit.Angle

ApogeeParallax returns equatorial horizontal parallax of the Moon at the Apogee nearest the given date.

Year is a decimal year specifying a date.

Example

// Example 50.a, p. 357.
p := apsis.ApogeeParallax(1988.75)
fmt.Printf("%.3f\n", p.Sec())
fmt.Printf("%0.3d\n", sexa.FmtAngle(p))

Output:

3240.679
54′00″.679

func MeanApogee

func MeanApogee(year float64) float64

MeanApogee returns the jde of the mean apogee of the Moon nearest the given date. 平远地点

Year is a decimal year specifying a date.

Example

package main

import (
	"fmt"

	"github.com/mooncaker816/learnmeeus/v3/apsis"
)

func main() {
	// Example 50.a, p. 357.
	fmt.Printf("JDE = %.4f\n", apsis.MeanApogee(1988.75))
}

Output:

JDE = 2447442.8191

func MeanPerigee

func MeanPerigee(year float64) float64

MeanPerigee returns the jde of the mean perigee of the Moon nearest the given date. 平近地点

Year is a decimal year specifying a date.

func Perigee

func Perigee(year float64) float64

Perigee returns the jde of perigee of the Moon nearest the given date. 近地点

Year is a decimal year specifying a date.

func PerigeeParallax

func PerigeeParallax(year float64) unit.Angle

PerigeeParallax returns equatorial horizontal parallax of the Moon at the Perigee nearest the given date.

Year is a decimal year specifying a date.