Opposition

by Dominic Ford, Editor
Last updated: 16 Jul 2020
Opposition

Mars at opposition in 2001, as seen by the Hubble Space Telescope. Image courtesy of NASA.

An astronomical body is said to be at opposition when it makes its closest approach to the point directly opposite to the Sun in the night sky.

This means that the object will appear highest in the sky at around midnight, local time, and will be above the horizon for much of the night.

For objects which orbit further out in the Solar System than the Earth – almost all bodies other than Mercury and Venus – this configuration happens when the Solar System is aligned such that the object lies in a straight line with the Earth and the Sun, the Earth being in the middle.

Consequently, this is also the time when the object makes its closest approach to the Earth, making it appear at its largest and brightest in the night sky.

List of oppositions

The table below lists the dates when objects are at opposition in 2021, computed from NASA's DE430 planetary ephemeris. To show events in other years, use the control below.

Change year

Objects at opposition in 2021

Date Object Declination
Date Object Declination
21 Jan 2021 21:34 UTC15 Eunomia at opposition16°48'NMore information »
24 Jan 2021 14:22 UTC14 Irene at opposition28°37'NMore information »
02 Feb 2021 21:34 UTC18 Melpomene at opposition11°52'NMore information »
22 Feb 2021 16:46 UTC29 Amphitrite at opposition13°40'NMore information »
04 Mar 2021 23:58 UTC4 Vesta at opposition15°57'NMore information »
27 Mar 2021 14:42 UTC136472 Makemake at opposition23°16'NMore information »
05 Apr 2021 04:46 UTC9 Metis at opposition0°57'NMore information »
18 Apr 2021 00:03 UTC136108 Haumea at opposition16°05'NMore information »
04 Jun 2021 07:10 UTC63 Ausonia at opposition33°21'SMore information »
18 Jul 2021 06:20 UTC134340 Pluto at opposition22°34'SMore information »
18 Jul 2021 21:34 UTC6 Hebe at opposition10°35'SMore information »
30 Jul 2021 19:10 UTC12 Victoria at opposition1°10'SMore information »
02 Aug 2021 06:01 UTCSaturn at opposition18°31'SMore information »
12 Aug 2021 21:34 UTC349 Dembowska at opposition26°27'SMore information »
19 Aug 2021 19:10 UTC43 Ariadne at opposition6°32'SMore information »
20 Aug 2021 00:16 UTCJupiter at opposition13°38'SMore information »
24 Aug 2021 14:22 UTC89 Julia at opposition0°15'SMore information »
11 Sep 2021 19:10 UTC2 Pallas at opposition0°16'SMore information »
14 Sep 2021 09:06 UTCNeptune at opposition4°27'SMore information »
02 Oct 2021 02:22 UTC40 Harmonia at opposition3°43'SMore information »
17 Oct 2021 16:32 UTC136199 Eris at opposition1°19'SMore information »
04 Nov 2021 23:43 UTCUranus at opposition15°10'NMore information »
27 Nov 2021 07:00 UTC1 Ceres at opposition16°44'NMore information »
10 Dec 2021 19:10 UTC44 Nysa at opposition17°24'NMore information »

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