Search for the next planetary apsis

Finds the date and time of a planet's perihelion (closest approach to the Sun) or aphelion (farthest distance from the Sun) after a given time.

Usage

search_planet_apsis(body, start_time)

Arguments

body

Integer constant identifying the planet. Use astro_body["PLANET_NAME"] where PLANET_NAME is one of: "MERCURY", "VENUS", "EARTH", "MARS", "JUPITER", "SATURN", "URANUS", "NEPTUNE", or "PLUTO". Not allowed to be "SUN" or "MOON".

start_time

A POSIXct value indicating the date and time at which to start searching for the next perihelion or aphelion.

Value

A list containing:

kind

An integer flag: 0 for perihelion, 1 for aphelion.

time

A POSIXct value representing the date and time of the next planetary apsis.

dist_au

The distance from the planet to the Sun in astronomical units.

dist_km

The distance from the planet to the Sun in kilometers.

Details

The closest point is called perihelion and the farthest point is called aphelion. To iterate through consecutive alternating perihelion and aphelion events, call search_planet_apsis() once, then use the return value to call next_planet_apsis(). After that, keep feeding the previous return value into another call of next_planet_apsis() as many times as desired.

See also

next_planet_apsis()

Examples

# Find the next perihelion/aphelion of Mars after 2025-01-01
start <- as.POSIXct("2025-01-01", tz = "UTC")
apsis <- search_planet_apsis(astro_body["MARS"], start)
apsis
#> $kind
#> [1] 1
#> 
#> $time
#> [1] "2025-04-16 22:54:51 UTC"
#> 
#> $dist_au
#> [1] 1.666058
#> 
#> $dist_km
#> [1] 249238699
#>