I just happen to be making astronomical calculations in perl and noticing that the sun is really near 0 right ascension and declination. Hmm. That would be the vernal equinox, right? I always like to calculate things like this exactly if I happen to have the time and a nearby laptop. I'm getting output I don't understand, so I think I'm in a better place to ask a cohesive question. What's more, I think I can get to it without needing to resort to readmore tags.

I found an old thread where haukex had helped me figure out some of this: Re: calculate length of day as function of space at onset of fall, and started folding in the old code into the new. I write some really primitive-looking code looking back, but it's my learning on display. Out of this I made a githubpull request, simply to try to understand how github works, and I really don't get it still, which defines me clearly as an intermediate perl user that I am struggling with it. This is what I had some code at github that calculates equinoxes, sunsets, meridians.

Anyways, so I start chopping that up and am left 3 lines, and then I hardcode the year:

use Astro::Utils;
my $spring   = calculate_equinox( 'mar', 'utc', '2021' );
$logger->info("spring begins $spring");
[download]

I'll list output, source and then have a couple questions.

$ ./3.vernal.pl
./3.vernal.pl 
Name    Right Ascension        Declination 
Mars    1.19220473652282    0.409015700183571 
Moon    1.6536783961676    0.442537954264476 
Sun    0.0202246733370893    0.00876435085335973 
Aldeb    1.20392811802569    0.288139315093836  
Time is Sun Mar 21 17:03:18 2021 
Julian day is 2459295.460625 
Sun set is Mon Mar 22 01:58:54 2021 
Astro::Coord::ECI=HASH(0x560eda31aa70) 
spring begins 2021-03-20 09:37:05 
$ cat 3.vernal.pl
[download]

#!/usr/bin/perl 

use Time::Piece;
use Astro::Coord::ECI::Utils 'deg2rad';
use Astro::Coords;
use Log::Log4perl;
use 5.030;

my $file = '/home/hogan/Documents/hogan/logs/3.log4perl.txt';

unlink $file or warn "Could not unlink $file: $!";
my $log_conf4 = "/home/hogan/Documents/hogan/logs/conf_files/3.conf";
Log::Log4perl::init($log_conf4);    #info
my $logger = Log::Log4perl->get_logger();
$logger->info("$0");

$logger->info("Name\tRight Ascension\t\tDeclination");

for my $name (qw/Mars Moon Sun/) {

  my $planet2 = Astro::Coords->new( planet => $name );

  $planet2->datetime( Time::Piece->new );

  my $ra  = $planet2->ra( format => q/rad/ );
  my $dec = $planet2->dec( format => q/rad/ );

  $logger->info("$name\t$ra\t$dec");

}

## declare values and tailor to what these routines expect...
my $aldeb_ra_degrees          = 68.98;
my $aldeb_ra_radians          = deg2rad($aldeb_ra_degrees);
my $aldeb_declination_degrees = 16.509166666667;
my $aldeb_dec_radians         = deg2rad($aldeb_declination_degrees);
my $local_lat                 = deg2rad(43.6135);                   # 
+Radians
my $local_long                = deg2rad(-116.20345);                # 
+Radians
my $local_alt                 = 8321 / 1000;                        # 
+Kilometers

$logger->info("Aldeb\t$aldeb_ra_radians\t$aldeb_dec_radians ");
my $t  = localtime;
my $jd = $t->julian_day;

$logger->info("Time is $t");
$logger->info("Julian day is $jd");

use Astro::Coord::ECI::Sun;

my $sun = Astro::Coord::ECI::Sun->new();
my $sta = Astro::Coord::ECI->universal( time() )
  ->geodetic( $local_lat, $local_long, $local_alt );
my ( $time, $rise ) = $sta->next_elevation($sun);
my $string =
  "Sun @{[$rise ? 'rise' : 'set']} is " . scalar gmtime $time . " UT\n
+";
$logger->info("$string");
$logger->debug("$sta");

# calculate begin of spring
use Astro::Utils;
my $spring   = calculate_equinox( 'mar', 'utc', '2021' );
$logger->info("spring begins $spring");

__END__ 

$
[download]

As I look at the data, does it not say that spring has already sprung? Here's question 1: Is the value for $spring correct?

If $spring is correct, then has spring sprung? If so, why are the values for the sun's declination and right ascension still so unzeroish?

Thanks for your comments,