Solar System Phenomena — Uranus in 2021

The path of Uranus against the background stars in 2021

The chart shows the path of Uranus across the background stars over the course of the year. Stars to magnitude +9.5 are shown. The white circles represent the planet on the first day of the month and are scaled according to apparent magnitude. The faint paths before the first circle and after the last circle represent the planet's positions in December of last year and January of next. In general, the planet moves from right to left except when it's in retrograde and proceding in the opposite direction.

The lower chart shows how the appearance of Uranus changes over the year. Below each image is listed the date, the apparent magnitude, the apparent diameter of the disk (in arc-seconds) and the geocentric distance (in au). Because the relative distance of Uranus does not greatly vary throughout the year, neither does its appearance through a telescope.

Uranus hovers around sixth magnitude so it is best viewed with some kind of optical aid. It enters the year in retrograde motion in the evening sky and sees a much brighter Mars glide past in late January. Its closer encounters with Mercury and Venus occur too close to conjunction in April to be visible. The green ice giant reappears at dawn in late May. Its position in the constellation of Aries means that northern hemisphere observers have the best views of this faint planet. Uranus passes by the sixth-magnitude star ο Arietis twice, in June and October, on its way to opposition in early November. In addition, the Moon makes a series of increasingly close flypasts; next year these will become lunar occultations.

12 Januarymaximum declination south
14 Januarystationary point in right ascension: retrograde → direct
20 Januaryplanetary conjunction: 1.6° south of Mars
26 Januaryeast quadrature
17 February3.0° north of the Moon
17 March2.7° north of the Moon
13 April2.5° north of the Moon
23 Aprilplanetary conjunction: 0.3° north of Venus
24 Aprilplanetary conjunction: 0.7° south of Mercury
30 Aprilconjunction
10 May2.4° north of the Moon
07 June2.1° north of the Moon
04 July1.9° north of the Moon
01 August1.7° north of the Moon
07 Augustwest quadrature
19 Augustmaximum declination north
20 Auguststationary point in right ascension: direct → retrograde
28 August1.4° north of the Moon
24 September1.3° north of the Moon
21 October1.3° north of the Moon
05 Novemberopposition: magnitude +5.7, apparent diameter 3.7 arc-seconds
18 November1.5° north of the Moon
15 December1.5° north of the Moon


The dates, times and circumstances of all planetary and lunar phenomena were calculated from the JPL DE406 solar system ephemeris using the same rigorous methods that are employed in the compilation of publications such as The Astronomical Almanac.