-- earth.adb   some Constants and equations about earth and sun

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Numerics.Elementary_Functions; 
procedure Earth is

  use Ada.numerics;
  use Elementary_Functions;

  package FLT_IO is new Ada.Text_IO.Float_IO(float); use FLT_IO;

  E_Radius     : float := 6370.0; -- KM
 
  E_Mass       : float := 5.97E24; -- Kg

  E_Cir_Area   : float := Pi * E_Radius * E_Radius; -- KM**2

  Orbit_Time   : float := 365.2422 * 24.0 * 3600.0; -- seconds in a year

  Orbit_R      : float := 149.0E6; -- KM

  Orbit_Circum : float := 2.0 * Pi * Orbit_R; -- KM

  Orbit_vel    : float := Orbit_Circum / Orbit_Time; -- KM/sec

  Sun_Radius   : float := 696000.0; -- KM

  Sun_Mass     : float := 333000.0 * E_Mass; -- Kg

  G_univers    : float := 6.672E-11; -- nt meter**2 /Kg**2

  -- multiply by 1000 to convert KM to meters, KM/sec to meters/sec

  F_centrip    : float := (E_Mass * (Orbit_vel * 1000.0)**2 ) / 
                          (Orbit_R * 1000.0); -- newtons

  F_attrac     : float := (G_univers * E_Mass * Sun_Mass) /
                          (Orbit_R*1000.0 * Orbit_R*1000.0); -- newtons

begin

  Put_Line("Earth - Sun data");

  Put(E_Radius); Put_Line(" = Earth radius in KM");
 
  Put(E_Mass); Put_Line(" = Earth mass in Kg");

  Put(E_Cir_Area); Put_line(" = Earth circular area in  KM**2");

  Put(Orbit_Time); Put_Line(" = Orbit time, seconds in a year");

  Put(Orbit_R); Put_Line(" = Orbit radius in KM");

  Put(Orbit_Circum); Put_Line(" = Orbit circumfrence in KM");

  Put(Orbit_vel); Put_line(" = Orbital velocity in KM/sec");

  Put(Sun_Radius); Put_Line(" = Sun radius in KM");

  Put(Sun_Mass); Put_line(" = Sun mass in Kg");

  Put(G_univers); Put_line(" = universal gravitational constant in nt meter**2 /Kg**2");

  Put(F_centrip); Put_Line(" = Centripital force in newtons");

  Put(F_attrac); Put_Line(" = Force of attraction in newtons");

end Earth;