Saturn will reach
opposition, when it lies opposite to the Sun in the sky.
Lying in the constellation
Aquarius, it will be visible for much of the night, reaching its
highest point in the sky around midnight local time.
From Los Angeles, it will be visible between 20:12 and 05:39. It will become accessible at around 20:12, when it rises to an altitude of 11° above your eastern horizon. It will reach its highest point in the sky at 00:56, 48° above your southern horizon. It will become inaccessible at around 05:39 when it sinks below 11° above your western horizon.
2024 apparition of Saturn
A close approach to the Earth
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.
This happens because when Saturn lies opposite to the Sun in the sky, the
Earth passes between Saturn and the Sun. The
solar system is lined up with Saturn and the Earth on the same side of the Sun,
as shown by the configuration labelled perigee in the diagram below:
When a planet is at opposition, the solar system is aligned such that the planet
lies on the same side of the Sun as the Earth. At this time, the planet makes its
perigee, or closest approach to the Earth.
Not drawn to scale.
The panels below show a comparison of the apparent size of Saturn when seen
at opposition in 2024, and when it is most
distant from the Earth at
solar conjunction.
A comparison of the size of Saturn as seen at 2024 opposition and
at solar conjunction.
In practice, however, Saturn orbits much further out in the solar system
than the Earth – at an average distance from the Sun of
9.54 times that of the Earth,
and so its
angular size does not vary much as it cycles between
opposition and
solar conjunction.
The rings of Saturn
Saturn’s rings will appear very close to edge-on at this opposition.
The graph below shows the changing inclination of Saturn’s rings
over time. The black line indicates their inclination to our line of sight from
the Earth. A negative angle indicates that the north pole is tipped towards us,
while a positive angle indicates that we see the south pole. An angle close to
zero means that Saturn’s rings appear close to edge on.
The red line indicates the inclination of the rings to the Sun’s line of
sight to the planet. Interesting phenomena can occur when the rings are very
close to edge-on, if the Sun illuminates one side of the rings, while we see
the other. At such times, we see the unilluminated side of the rings.
The Seeliger Effect
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.
Observing Saturn
At opposition, Saturn is visible for much of the night. When it lies opposite
to the Sun in the sky, this means that it rises at around the time the Sun sets, and it sets at
around the time the Sun rises. It reaches its
highest point in the sky at
around midnight local time.
But even when it is at its closest point to the Earth,
it is not possible to distinguish it as more than a
star-like point of light
without the aid of a telescope.
A chart of the path of Saturn across the sky in 2024 can be found here, and a chart of its rising and setting times here.
At the moment of opposition, Saturn will lie at a distance of
8.66 AU,
and its disk will measure
19.2 arcsec
in diameter, shining at magnitude 0.6.
Its celestial coordinates at the moment it passes opposition will be:
Object | Right Ascension | Declination | Constellation | Magnitude | Angular Size |
Saturn | 23h10m40s | 7°39’S | Aquarius | 0.6 | 19.2″ |
The coordinates above are given in J2000.0.
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 while remaining visible in the evening
sky for a few months.
The sky on 7 Sep 2024
Source
The circumstances of this event were computed using the DE430 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
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Image credit
© NASA/Cassini