Uranus at opposition

Dominic Ford, Editor
From the Outer Planets feed


Objects: Uranus

Across much of the world Uranus will reach opposition, when it lies opposite to the Sun in the sky. Lying in the constellation Capricornus, it will be visible for much of the night, reaching its highest point in the sky around midnight local time.

From London however, it will not be readily observable since it will lie so far south that it will never rise more than 18° above the horizon.

2080 apparition of Uranus

09 May 2080 – Uranus enters retrograde motion
25 Jul 2080 – Uranus at opposition
10 Oct 2080 – Uranus ends retrograde motion

A close approach to the Earth

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

This happens because when Uranus lies opposite to the Sun in the sky, the Earth passes between Uranus and the Sun. The solar system is lined up with Uranus 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, Uranus orbits much further out in the solar system than the Earth – at an average distance from the Sun of 19.19 times that of the Earth, and so its angular size does not vary much as it cycles between opposition and solar conjunction.

Observing Uranus

At opposition, Uranus 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 Uranus across the sky in 2080 can be found here, and a chart of its rising and setting times here.

At the moment of opposition, Uranus will lie at a distance of 18.76 AU, and its disk will measure 3.8 arcsec in diameter, shining at magnitude 5.7. Its celestial coordinates at the moment it passes opposition will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Uranus 20h20m10s 20°09'S Capricornus 5.7 3.8"

The coordinates above are given in J2000.0.

Over the weeks following its opposition, Uranus 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 19 May 2024

The sky on 19 May 2024
Sunrise
05:00
Sunset
20:51
Twilight ends
00:10
Twilight begins
01:40


Waxing Gibbous

89%

11 days old

Planets
Rise Culm. Set
Mercury 04:27 11:23 18:20
Venus 04:56 12:38 20:19
Moon 16:28 22:10 03:38
Mars 03:38 10:04 16:30
Jupiter 05:06 12:54 20:41
Saturn 02:57 08:28 13:58
All times shown in BST.

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 Jul 2080  –  Uranus at opposition
10 Oct 2080  –  Uranus ends retrograde motion
13 May 2081  –  Uranus enters retrograde motion
30 Jul 2081  –  Uranus at opposition

Image credit

© NASA/Voyager 2

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