© NASA/Voyager 2

Neptune at opposition

Dominic Ford, Editor
From the Outer Planets feed

Objects: Neptune
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Neptune will reach opposition, when it lies opposite to the Sun in the sky. Lying in the constellation Pisces, it will be visible for much of the night, reaching its highest point in the sky around midnight local time.

From San Diego, it will be visible between 20:31 and 04:58. It will become accessible around 20:31, when it rises to an altitude of 21° above your eastern horizon. It will reach its highest point in the sky at 00:45, 57° above your southern horizon. It will become inaccessible around 04:58 when it sinks below 22° above your western horizon.

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2026 apparition of Neptune

07 Jul 2026 – Neptune enters retrograde motion
25 Sep 2026 – Neptune at opposition
12 Dec 2026 – Neptune ends retrograde motion

A close approach to the Earth

At around the same time that Neptune passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest.

This happens because when Neptune lies opposite to the Sun in the sky, the Earth passes between Neptune and the Sun. The solar system is lined up with Neptune 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.

In practice, however, Neptune orbits much further out in the solar system than the Earth – at an average distance from the Sun of 30.07 times that of the Earth, and so its angular size does not vary much as it cycles between opposition and solar conjunction.

Observing Neptune

At opposition, Neptune 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 Neptune across the sky in 2026 can be found here, and a chart of its rising and setting times here.

At the moment of opposition, Neptune will lie at a distance of 28.88 AU, and its disk will measure 2.4 arcsec in diameter, shining at magnitude 7.8. Its celestial coordinates at the moment it passes opposition will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Neptune 00h11m50s 0°15'S Pisces 7.8 2.4"

The coordinates above are given in J2000.0.

Over the weeks following its opposition, Neptune 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 25 September 2026
Sunrise
06:38
Sunset
18:42
Twilight ends
20:06
Twilight begins
05:14

14-day old moon
Waxing Gibbous

99%

14 days old

Planets
Rise Culm. Set
Mercury 08:20 13:57 19:33
Venus 09:32 14:40 19:49
Moon 17:39 --:-- 05:37
Mars 01:32 08:33 15:35
Jupiter 03:11 09:56 16:41
Saturn 19:11 01:19 07:27
All times shown in PDT.

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.

Related news

25 Sep 2026  –  Neptune at opposition
28 Sep 2027  –  Neptune at opposition
29 Sep 2028  –  Neptune at opposition
02 Oct 2029  –  Neptune at opposition

Image credit

© NASA/Voyager 2

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