Barycentric position and velocity vectors

Calculates the barycentric (solar system barycenter) position and velocity vectors for a given celestial body at a specified time.

Usage

astro_bary_state(body, time)

Arguments

body

Identifier of celestial body (e.g., astro_body["MERCURY"]).

time

A POSIXct time value.

Value

A list with elements:

x

X position in AU.

y

Y position in AU.

z

Z position in AU.

vx

X velocity in AU/day.

vy

Y velocity in AU/day.

vz

Z velocity in AU/day.

time

Observation time as POSIXct.

Details

The vectors are expressed in J2000 mean equator coordinates (the mean equator of the Earth at noon UTC on 1 January 2000).

Examples

time <- as.POSIXct("2025-02-19 22:10:12", tz = "UTC")
astro_bary_state(astro_body["MARS"], time)
#> $x
#> [1] -1.099886
#> 
#> $y
#> [1] 1.106853
#> 
#> $z
#> [1] 0.5375253
#> 
#> $vx
#> [1] -0.009936038
#> 
#> $vy
#> [1] -0.00745567
#> 
#> $vz
#> [1] -0.003151791
#> 
#> $time
#> [1] "2025-02-19 22:10:12 UTC"
#>