Saturn will be well placed for observation, lying
in the constellation Libra, far above the horizon for much of
Regardless of your location on the Earth, Saturn
will reach its highest point in the sky at around
midnight local time.
This optimal positioning occurs when Saturn makes its closest approach
to the point directly opposite to the Sun in the sky – an event termed
opposition, the exact moment of which will be 14:15 EDT. Since the
Sun reaches its greatest distance below the horizon at midnight, the point
opposite to it is highest in the sky at the same time.
At around the same time that Saturn passes opposition, it also makes
its closest approach to the Earth – termed its perigee –
making it appear at its brightest and largest
in the night sky. This happens because when Saturn lies opposite to the
Sun in the night sky, the Solar System is lined up so that Saturn, the
Earth and the Sun lie in a straight line with the Earth in the middle, on the
same side of the Sun as Saturn.
In practice, however, Saturn orbits much further out in the Solar System than the Earth – at an average distance from the Sun of 9.56 AU
as compared to the Earth's average distance of
1 AU – and so its angular size does not
vary much as it cycles between opposition and solar conjunction.
On this occasion, Saturn will lie at a distance of 8.90 AU,
and its disk will measure
in diameter, shining at magnitude 0.8. Even at its closest approach
to the Earth, however, it is not possible to distinguish it as more than a
star-like point of light
with the naked eye, though a simple pair of binoculars are sufficient to reveal it as a disk of light with accompanying system of moons.
For a few hours around the exact moment of opposition, it may be possible to
discern a marked brightening of Saturn's rings in comparison to the planet's
disk, known as the Seeliger Effect. This occurs because Saturn's rings are
made of a fine sea of ice particles which are normally illuminated by the Sun
at a slightly different angle from our viewing angle, so that we see some
illuminated particles and some which are in the shadow of others. At around
the time of opposition, however, the ice particles are illuminated from almost
exactly the same direction from which we view them, meaning that we see very
few which are in shadow.
Over the weeks following its opposition, Saturn will reach
its highest point in the sky four minutes earlier each night, gradually
receding from the pre-dawn morning sky whilst remaining visible in the evening
sky for a few months.
A chart of the path of Saturn across the night sky can be found here, and a chart of its rising and setting times here.
The detailed circumstances of this event are:
The coordinates above are given in J2000.0.
The sky on Sat, 10 May 2014
The circumstances of this event were computed from the DE405 ephemeris published by the Jet Propulsion Laboratory (JPL).