Heliocentric position vector of a celestial body

Calculates the position of a celestial body as a vector using the center of the Sun as the origin. The result is expressed as a Cartesian vector in the J2000 equatorial system (the mean equator of the Earth at noon UTC on 1 January 2000).

Usage

astro_helio_vector(body, time)

Arguments

body

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

time

A POSIXct time value.

Value

A list with elements:

x

X coordinate in AU.

y

Y coordinate in AU.

z

Z coordinate in AU.

time

Observation time as POSIXct.

Details

The position is not corrected for light travel time or aberration.

Examples

time <- as.POSIXct("2025-02-19 22:10:12", tz = "UTC")
astro_helio_vector(astro_body[["MARS"]], time)
#> $x
#> [1] -1.094507
#> 
#> $y
#> [1] 1.11158
#> 
#> $z
#> [1] 0.5393855
#> 
#> $time
#> [1] "2025-02-19 22:10:12 UTC"
#>