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Invert the AstroGeo22 precession curve: Earth-Moon state for a measured precession frequency / period.

Source: R/earthmoon_from_precession.R
earthmoon_from_precession.Rd

The model curve is not strictly monotonic (tidal resonances), so every crossing is returned.

Usage

earthmoon_from_precession(
  p_kyr = NULL,
  p_arcsec = NULL,
  method = c("astrogeo22", "angular_momentum"),
  obliquity_deg = NULL,
  age_range = NULL,
  data_dir = NULL
)

Arguments

p_kyr

Period of the axial precession, in kyr (numeric, scalar or vector, > 0; about 25.7 kyr today), i.e. 360 * 3600 / (p_kyr * 1000) arcsec/yr. Ignored when p_arcsec is given; one of the two is required. Default=NULL.

p_arcsec

Precession constant (rate of axial precession), in arcsec/yr (numeric, scalar or vector, > 0; about 50.47 today). Takes precedence over p_kyr. Default=NULL.

method

How the Earth-Moon state is found (character): "astrogeo22" finds every age at which the AstroGeo22 precession curve crosses the requested value (the curve is not monotonic, so several ages may be returned) and returns the AstroGeo22 state there; "angular_momentum" solves for the Earth-Moon distance (25 to 80 Earth radii) that gives the requested precession with precession_frequency, assuming conservation of the Earth-Moon angular momentum. Default=c("astrogeo22", "angular_momentum"), i.e. "astrogeo22".

obliquity_deg

Obliquity of the Earth, in degrees (numeric), used by method="angular_momentum"; NULL uses the present-day value 23.2545. Default=NULL.

age_range

Age range to which the search along the AstroGeo22 curve is restricted, in Ma (numeric vector c(min, max), or NULL for the whole curve). Only used with method="astrogeo22". Default=NULL.

data_dir

Directory that contains the file AstroGeo22.txt (character, or NULL); NULL uses the data installed with the package (or options(cocoR.data = ...)). Default=NULL.