node

Documentation

Overview

Node: Chapter 39, Passages through the Nodes.

Index

• func EllipticAscending(axis, ecc float64, argP unit.Angle, timeP float64) (jde, r float64)
• func EllipticDescending(axis, ecc float64, argP unit.Angle, timeP float64) (jde, r float64)
• func ParabolicAscending(q float64, argP unit.Angle, timeP float64) (jde, r float64)
• func ParabolicDescending(q float64, argP unit.Angle, timeP float64) (jde, r float64)

Examples

• EllipticAscending
• EllipticAscending (Venus)
• EllipticDescending
• ParabolicAscending
• ParabolicDescending

Functions

func EllipticAscending

func EllipticAscending(axis, ecc float64, argP unit.Angle, timeP float64) (jde, r float64)

EllipticAscending computes time and distance of passage through the ascending node of a body in an elliptical orbit.

Argument axis is semimajor axis in AU, ecc is eccentricity, argP is argument of perihelion, timeP is time of perihelion as a jd.

Result is jde of the event and distance from the sun in AU.

Example

package main

import (
	"fmt"
	"time"

	"github.com/soniakeys/meeus/v3/julian"
	"github.com/soniakeys/meeus/v3/node"
	"github.com/soniakeys/unit"
)

func main() {
	// Example 39.a, p. 276
	t, r := node.EllipticAscending(17.9400782, .96727426,
		unit.AngleFromDeg(111.84644),
		julian.CalendarGregorianToJD(1986, 2, 9.45891))
	y, m, d := julian.JDToCalendar(t)
	fmt.Printf("%d %s %.2f\n", y, time.Month(m), d)
	fmt.Printf("%.4f AU\n", r)
}

Output:

1985 November 9.16
1.8045 AU

Example (Venus)

package main

import (
	"fmt"
	"time"

	"github.com/soniakeys/meeus/v3/julian"
	"github.com/soniakeys/meeus/v3/node"
	"github.com/soniakeys/meeus/v3/perihelion"
	"github.com/soniakeys/meeus/v3/planetelements"
)

func main() {
	// Example 39.c, p. 278
	var k planetelements.Elements
	planetelements.Mean(planetelements.Venus,
		julian.CalendarGregorianToJD(1979, 1, 1), &k)
	t, _ := node.EllipticAscending(k.Axis, k.Ecc,
		k.Peri-k.Node,
		perihelion.Perihelion(perihelion.Venus, 1979))
	y, m, d := julian.JDToCalendar(t)
	fmt.Printf("%d %s %.3f\n", y, time.Month(m), d)
}

Output:

1978 November 27.409

func EllipticDescending

func EllipticDescending(axis, ecc float64, argP unit.Angle, timeP float64) (jde, r float64)

EllipticDescending computes time and distance of passage through the descending node of a body in an elliptical orbit.

Argument axis is semimajor axis in AU, ecc is eccentricity, argP is argument of perihelion, timeP is time of perihelion as a jd.

Result is jde of the event and distance from the sun in AU.

Example

package main

import (
	"fmt"
	"time"

	"github.com/soniakeys/meeus/v3/julian"
	"github.com/soniakeys/meeus/v3/node"
	"github.com/soniakeys/unit"
)

func main() {
	// Example 39.a, p. 276
	t, r := node.EllipticDescending(17.9400782, .96727426,
		unit.AngleFromDeg(111.84644),
		julian.CalendarGregorianToJD(1986, 2, 9.45891))
	y, m, d := julian.JDToCalendar(t)
	fmt.Printf("%d %s %.2f\n", y, time.Month(m), d)
	fmt.Printf("%.4f AU\n", r)
}

Output:

1986 March 10.37
0.8493 AU

func ParabolicAscending

func ParabolicAscending(q float64, argP unit.Angle, timeP float64) (jde, r float64)

ParabolicAscending computes time and distance of passage through the ascending node of a body in a parabolic orbit.

Argument q is perihelion distance in AU, argP is argument of perihelion, timeP is time of perihelion as a jd.

Result is jde of the event and distance from the sun in AU.

Example

package main

import (
	"fmt"
	"time"

	"github.com/soniakeys/meeus/v3/julian"
	"github.com/soniakeys/meeus/v3/node"
	"github.com/soniakeys/unit"
)

func main() {
	// Example 29.b, p. 277
	t, r := node.ParabolicAscending(1.324502,
		unit.AngleFromDeg(154.9103),
		julian.CalendarGregorianToJD(1989, 8, 20.291))
	y, m, d := julian.JDToCalendar(t)
	fmt.Printf("%d %s %d\n", y, time.Month(m), int(d))
	fmt.Printf("%.2f AU\n", r)
}

Output:

1977 September 17
28.07 AU

func ParabolicDescending

func ParabolicDescending(q float64, argP unit.Angle, timeP float64) (jde, r float64)

ParabolicDescending computes time and distance of passage through the descending node of a body in a parabolic orbit.

Argument q is perihelion distance in AU, argP is argument of perihelion, timeP is time of perihelion as a jd.

Result is jde of the event and distance from the sun in AU.

Example

package main

import (
	"fmt"
	"time"

	"github.com/soniakeys/meeus/v3/julian"
	"github.com/soniakeys/meeus/v3/node"
	"github.com/soniakeys/unit"
)

func main() {
	// Example 29.b, p. 277
	t, r := node.ParabolicDescending(1.324502,
		unit.AngleFromDeg(154.9103),
		julian.CalendarGregorianToJD(1989, 8, 20.291))
	y, m, d := julian.JDToCalendar(t)
	fmt.Printf("%d %s %.3f\n", y, time.Month(m), d)
	fmt.Printf("%.4f AU\n", r)
}

Output:

1989 September 17.636
1.3901 AU