Merge pull request #24 from observerly/feature/solar/GetEclipticCoord…

…inate

feat: add GetEclipticCoordinate(datetime time.Time) to sun module in @observerly/sidera.

pkg/solar/sun.go

@@ -107,3 +107,26 @@ func GetEclipticLongitude(datetime time.Time) float64 {
 }
 
 /*****************************************************************************************************************/
+
+/*
+the Ecliptic Coordinate of the Sun for a given datetime
+
+The Solar Ecliptic Coordinate is the position of the Sun in the sky relative to the vernal equinox.
+
+The Solar Ecliptic Coordinate is an important concept in solar astronomy, as it is used to calculate the position
+of the Sun in the sky at any given time. By knowing the Solar Ecliptic Coordinate, an observer can determine the
+Sun's position relative to the vernal equinox and calculate the time of sunrise, sunset, and other solar events.
+*/
+func GetEclipticCoordinate(datetime time.Time) common.EclipticCoordinate {
+	// get the solar ecliptic longitude:
+	λ := GetEclipticLongitude(datetime)
+
+	// return the solar ecliptic coordinate:
+	// the solar ecliptic coordinate is the solar ecliptic longitude and zero latitude:
+	return common.EclipticCoordinate{
+		Longitude: λ,
+		Latitude:  0,
+	}
+}
+
+/*****************************************************************************************************************/

pkg/solar/sun_test.go

@@ -14,6 +14,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/observerly/sidera/pkg/common"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -55,3 +56,22 @@ func TestGetSolarEclipticLongitude(t *testing.T) {
 }
 
 /*****************************************************************************************************************/
+
+func TestGetSolarEclipticCoordinate(t *testing.T) {
+	var got = GetEclipticCoordinate(datetime)
+
+	var want = common.EclipticCoordinate{
+		Longitude: 51.96564888161902,
+		Latitude:  0,
+	}
+
+	if got.Longitude-want.Longitude > 0.0001 {
+		t.Errorf("got %f, wanted %f", got.Longitude, want.Longitude)
+	}
+
+	if got.Latitude-want.Latitude > 0.0001 {
+		t.Errorf("got %f, wanted %f", got.Latitude, want.Latitude)
+	}
+}
+
+/*****************************************************************************************************************/