Uranus ends retrograde motion

Dominic Ford, Editor
From the Outer Planets feed


Objects: Uranus

Uranus 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.

2235 apparition of Uranus

18 Mar 2235 – Uranus enters retrograde motion
01 Jun 2235 – Uranus at opposition
17 Aug 2235 – Uranus ends retrograde motion

Observing Uranus

Uranus leaves retrograde motion as its 2235 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:

Object Right Ascension Declination Constellation Magnitude Angular Size
Uranus 16h13m50s 21°07'S Scorpius 5.6 3.8"

The coordinates above are given in J2000.0.

From Cambridge , it will become visible at around 20:50 (EST), 22° above your south-western horizon, as dusk fades to darkness. It will then sink towards the horizon, setting at 23:56.

Over the following weeks, Uranus will reach its highest point in the sky four minutes earlier each night, gradually disappearing into evening twilight.

The sky on 4 Dec 2024

The sky on 4 December 2024
Sunrise
06:55
Sunset
16:11
Twilight ends
17:52
Twilight begins
05:14


Waxing Crescent

19%

3 days old

Planets
Rise Culm. Set
Mercury 07:10 11:48 16:26
Venus 10:13 14:44 19:16
Moon 10:22 14:38 19:00
Mars 19:57 03:25 10:52
Jupiter 16:17 23:47 07:17
Saturn 12:15 17:46 23:17
All times shown in EST.

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

17 Aug 2235  –  Uranus ends retrograde motion
21 Mar 2236  –  Uranus enters retrograde motion
05 Jun 2236  –  Uranus at opposition
21 Aug 2236  –  Uranus ends retrograde motion

Image credit

© NASA/Voyager 2

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