Convert J2000 equatorial coordinates to ecliptic coordinates

Converts equatorial coordinates in the J2000 frame (mean equator of Earth at noon UTC on 1 January 2000) to true ecliptic coordinates of date (relative to the plane of Earth's orbit on the given date).

Usage

astro_ecliptic(x, y, z, time)

Arguments

x: X coordinate in AU.
y: Y coordinate in AU.
z: Z coordinate in AU.
time: A POSIXct time value.

Value

A list with elements:

x: X coordinate (Cartesian) in ecliptic frame in AU.
y: Y coordinate (Cartesian) in ecliptic frame in AU.
z: Z coordinate (Cartesian) in ecliptic frame in AU.
lon: Ecliptic longitude in degrees.
lat: Ecliptic latitude in degrees.
dist: Distance in AU.
time: Observation time as POSIXct.

Examples

time <- as.POSIXct("2025-02-19 22:10:12", tz = "UTC")
astro_ecliptic(1.0, 0.5, 0.2, time)
#> $x
#> [1] 0.9966785
#> 
#> $y
#> [1] 0.5444227
#> 
#> $z
#> [1] -0.01535618
#> 
#> $lon
#> [1] 28.645
#> 
#> $lat
#> [1] -0.7746832
#> 
#> $time
#> [1] "2025-02-19 22:10:12 UTC"
#>