In case anyone's wondering what "currently" means, this is the code
which generates that text. The numbers are recalculated each time you
reload the page from the server. Don't bother hitting reload a lot,
though, as the probes are moving so slowly that the displayed numbers
will only change every couple of weeks or so. A tenth of an AU is a
long way.
The base data comes from the Voyager Mission Status pageVoyager Mission Status
Current positions and statuses of the two Voyager space probes. (Nasa Jet Propulsion Laboratory)
.
However, New Horizons is far from being the winner in overall
exploration.</p>
<?php
// Base time for the data below.
// $baseDate = '2021/03/07 07:37:00';
// $baseDt = new DateTime($baseDate, new DateTimeZone('UTC'));
// $baseTime = $baseDt->getTimestamp();
// echo "Base timestamp is $baseTime\n";
$baseTime = 1615102620;
// This is a simple linear extrapolation, which is technically wrong.
// However the deceleration of the V probes is so small that this should
// produce good answers for quite a while.
$v1Dist = 22761034890; // Base distance in km. from *Sun*
$v1Speed = 16.9995; // Base speed in km/s. wrt. Sun
$v2Dist = 18913379148;
$v2Speed = 15.3741;
$nowTime = time();
$elapsed = $nowTime - $baseTime;
$v1Now = $v1Dist + $v1Speed * $elapsed;
$v2Now = $v2Dist + $v2Speed * $elapsed;
$v1AU = $v1Now / 149597870.700; // Convert km to AU.
$v2AU = $v2Now / 149597870.700;
?>
<p>... Voyager 2 is <?php $this->lt('why/scalescode', "currently"); ?>
<?php echo number_format($v2AU, 1); ?> AU away from the Sun, and Voyager 1 is
<?php echo number_format($v1AU, 1); ?> AU away; making it not only the
farthest space probe, functioning or not, but in fact the farthest known
object in the solar system.</p>
