Changes in version 0.2.0                        

New features

  - Added drake_equation() — computes N, the estimated number of active,
    communicating civilisations in the Milky Way, from the seven classic
    Drake equation parameters (R_star, fp, ne, fl, fi, fc, L). Returns a
    named list with the numeric result, a substituted equation string,
    all input values, and a qualitative six-tier interpretation of N
    ranging from "effectively zero" (N < 0.001) to "galaxy teeming with
    life" (N ≥ 10 000).

Minor changes

  - DESCRIPTION updated to mention the Drake equation capability.
  - Version bumped to 0.2.0.

                 Changes in version 0.1.0 (2026-05-27)                  

  - Initial release of astronomR.
  - Angular conversion functions: deg_to_dms(), dms_to_deg(),
    deg_to_hms(), hms_to_deg(), deg2rad(), rad2deg().
  - Physical constants dataset constants_df and retrieval function
    constant_value().
  - Gaia Archive query function get_gaia_data().
  - Distance conversion functions km_to_Mpc() and Mpc_to_km().
  - Early-universe thermal physics functions:
    photon_energy_density_fn_T(), photon_energy_density_fn_z(),
    photon_number_density_fn_T(), photon_number_density_fn_z(),
    Saha_Xe(), and soln_saha().