The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.


Astro::SolarParallax - Find the Solar Parallax from Venus Transit


  use Astro::SolarParallax::Observer;
  use Astro::SolarParallax;
  use Geo::Coordinates;
  my $obs1 = new Geo::Coordinates;
  my $obs2 = new Geo::Coordinates;
  $obs1->latitude(78.20); # Longyearbyen
  $obs2->latitude(13.7307); # Bangkok
  my $observer1 = Astro::SolarParallax::Observer->new($obs1);
  my $observer2 = Astro::SolarParallax::Observer->new($obs2);
  # Longyearbyen
  $observer1->contacttime(1, "07:17:47");
  $observer1->contacttime(4, "13:21:00");
  # Bangkok
  $observer2->contacttime(1, "07:13:07");
  $observer2->contacttime(4, "13:20:36");
  my $measurement = Astro::SolarParallax->new($observer1, $observer2);
  print $measurement->AU(1,4);


This module is intended to be used to compute the solar parallax from planetary transits. Specifically, in the current implementation, it makes use of a method developed by F. Mignard, and is limited to the transit of Venus on 2004-06-08.

It has a object oriented interface.

new($obs1, $obs2)

This is the constructor of this class, it takes as argument two observers, that is, two objects of the Astro::SolarParallax::Observer class.


This method will return the distance to the sun in kilometers, based on the measurements done by the two observers given to the constructor. It takes as argument and array containing the number of the contact points, in ascending order.

The constraints in the Astro::SolarParallax::Observer apply.


This is the initial release. While it should be considered an alpha, the author do not expect any very substantial non-backwards compatible changes in the API of this class.

It has not been very thorougly tested in this release, specifically, it has not been compared to "known correct answers". It does, however, give answers of the right magnitude, and the intermediate numbers are identical to those of Mignard.

It is somewhat uncertain what happens if the observers come in an unanticipated order, whatever that means...

It currently supports only two observers, and there are many limitations on the data from these two observers. It should be possible to expand its scope, however.




F. Mignard: "The solar parallax with the transit of Venus", version 3, 2004-02-26.


Kjetil Kjernsmo,


Copyright (C) 2004 by Kjetil Kjernsmo

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.3 or, at your option, any later version of Perl 5 you may have available.