Neptune will reach the end of its retrograde motion,
ending its westward movement through the
constellations and returning to more usual eastward motion instead.
This reversal of direction is a phenomenon that all the solar system’s
outer planets periodically undergo, a few months after they pass
opposition.

This motion was known to ancient observers, and it troubled them as they could not reconcile it with
models in which the planets moved in uniform circular orbits around the Earth, as they believed.

The retrograde motion is caused by the Earth’s own motion around the Sun.
As the Earth circles the Sun, our perspective changes, and this causes the apparent positions of objects to
move from side-to-side in the sky with a one-year period. This nodding motion is super-imposed on the planet’s
long-term eastward motion through the constellations.

The diagram below illustrates this. The grey dashed arrow shows the Earth’s sight-line
to the planet, and the diagram on the right shows the planet’s apparently movement across the sky as seen from
the Earth:

The retrograde motion of a planet in the outer solar system.
Not drawn to scale.

2023 apparition of Neptune

Observing Neptune

Neptune leaves retrograde motion as its 2023 apparition
comes to an end, although it will remain visible for some weeks in the dusk sky.

Its celestial coordinates as it leaves retrograde motion will be:

The coordinates above are given in J2000.0.

From Los Angeles , it will be visible in the evening sky, becoming accessible around 17:46 (PST), 51° above your southern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 18:32, 52° above your southern horizon. It will continue to be observable until around 22:34, when it sinks below 21° above your western horizon.