Full Earth-Moon state from any one observable — earthmoon

Give exactly one of: `p_arcsec`/`p_kyr`/`k_yr` (precession), `a_RE`/`a_km` (Earth-Moon distance), `lod_h` (solar day), `months_per_year`, or an observed `cycle_kyr` together with its `term` (e.g. the obliquity cycle).

Usage

earthmoon_state(
  p_arcsec = NULL,
  p_kyr = NULL,
  k_yr = NULL,
  a_RE = NULL,
  a_km = NULL,
  lod_h = NULL,
  months_per_year = NULL,
  months_kind = "sidereal",
  cycle_kyr = NULL,
  term = "k+s3",
  method = c("angular_momentum", "astrogeo22"),
  obliquity_deg = NULL,
  age_ma = NULL,
  data_dir = NULL
)

Arguments

p_arcsec: Precession constant (rate of axial precession), in arcsec/yr (numeric, > 0; about 50.47 today). If several precession inputs are given, p_kyr wins over k_yr/cycle_kyr, which win over p_arcsec. Default=NULL.
p_kyr: Period of the axial precession, in kyr (numeric, > 0; about 25.7 today), converted to p_arcsec = 360 * 3600 / (p_kyr * 1000). Default=NULL.
k_yr: Period of the axial precession, in years (numeric, > 0; about 25700 today), converted to p_arcsec = 360 * 3600 / k_yr. Default=NULL.
a_RE: Earth-Moon distance, in Earth radii (numeric, > 0; about 60.14 today). Default=NULL.
a_km: Earth-Moon distance, in km (numeric, > 0; about 384400 today); converted to a_RE and takes precedence over it. Default=NULL.
lod_h: Length of the solar day, in hours (numeric, > 0); if no distance is given, the Earth-Moon distance is derived from it with moon_distance_from_lod. Default=NULL.
months_per_year: Number of lunar months per year (numeric, > 0), e.g. from fossil growth bands; converted to an Earth-Moon distance with moon_distance_from_months (takes precedence over a_RE and a_km). Default=NULL.
months_kind: Type of month counted in months_per_year (character): "sidereal" or "synodic". Default="sidereal".
cycle_kyr: Period of an observed astronomical cycle in the record, in kyr (numeric, > 0), converted to the precession constant with cycles_to_k using term; overrides k_yr and p_arcsec (but not p_kyr). Default=NULL.
term: Which astronomical term cycle_kyr is (character), passed to cycles_to_k: "k+s3" (obliquity) or a precession term "k+g5", "k+g2", "k+g4", "k+g3" (or another term containing k listed by astro_terms). Only used with cycle_kyr. Default="k+s3".
method: How the Earth's spin and the lunar distance are linked when a precession observable has to be inverted, passed to earthmoon_from_precession (character): "angular_momentum" (Earth-Moon angular momentum conserved) or "astrogeo22" (read off the Farhat et al. 2022 AstroGeo22 curve; then the obliquity and model age of the first matching age are returned). Not used when a distance, day length or number of months is given. Default=c("angular_momentum", "astrogeo22"), i.e. "angular_momentum".
obliquity_deg: Obliquity of the Earth, in degrees (numeric). NULL uses the AstroGeo22 value at age_ma if age_ma is given, otherwise the present-day value 23.2545. Default=NULL.
age_ma: Age in Ma (numeric), only used to take the AstroGeo22 obliquity when obliquity_deg=NULL. Default=NULL.
data_dir: Directory that contains the AstroGeo22 data files (character, or NULL); NULL uses the data installed with the package. Default=NULL.

Value

one-row-per-input data.frame with the precession constant, the Earth-Moon distance, the solar and sidereal day, days per year, sidereal and synodic months per year and the obliquity