The information linked was taken from In-The-Sky website by Dominc Ford.
(UTC = Coordinated Universal Time +00:00 / BST = British Summer Time +01:00)
January 2021
| 02 Jan 2021 | 13:50 UTC | The Earth at perihelion | Pisces |
| 03 Jan 2021 | – | Quadrantid meteor shower | Bootes |
| 06 Jan 2021 | 09:37 UTC | Moon at Last Quarter | Virgo |
| 09 Jan 2021 | 15:36 UTC | The Moon at perigee | Scorpius |
| 09 Jan 2021 | 21:14 UTC | Conjunction of Mercury and Saturn | Capricornus |
| 10 Jan 2021 | 16:09 UTC | Conjunction of Neptune and Ceres | Aquarius |
| 11 Jan 2021 | 11:06 UTC | Conjunction of Jupiter and Mercury | Capricornus |
| 11 Jan 2021 | 20:11 UTC | Conjunction of the Moon and Venus | Sagittarius |
| 12 Jan 2021 | 23:50 UTC | The Moon at perihelion | Sagittarius |
| 13 Jan 2021 | 05:00 UTC | New Moon | Sagittarius |
| 14 Jan 2021 | 08:14 UTC | Conjunction of the Moon and Mercury | Capricornus |
| 14 Jan 2021 | 21:26 UTC | 134340 Pluto at solar conjunction | Sagittarius |
| 19 Jan 2021 | – | γ-Ursae Minorid meteor shower | Ursa Minor |
| 20 Jan 2021 | 21:02 UTC | Moon at First Quarter | Pisces |
| 21 Jan 2021 | 05:36 UTC | Conjunction of the Moon and Mars | Aries |
| 21 Jan 2021 | 13:10 UTC | The Moon at apogee | Aries |
| 21 Jan 2021 | 21:34 UTC | Asteroid 15 Eunomia at opposition | Cancer |
| 21 Jan 2021 | 23:34 UTC | Conjunction of Mars and Uranus | Aries |
| 24 Jan 2021 | 01:59 UTC | Mercury at greatest elongation east | Capricornus |
| 24 Jan 2021 | 03:04 UTC | Saturn at solar conjunction | Capricornus |
| 24 Jan 2021 | 14:22 UTC | Asteroid 14 Irene at opposition | Cancer |
| 25 Jan 2021 | 07:37 UTC | Mercury at dichotomy | Capricornus |
| 27 Jan 2021 | – | Mercury reaches highest point in evening sky | Capricornus |
| 28 Jan 2021 | 19:16 UTC | Full Moon | Cancer |
| 29 Jan 2021 | 00:35 UTC | Conjunction of Venus and Pluto | Sagittarius |
| 29 Jan 2021 | 01:44 UTC | Jupiter at solar conjunction | Capricornus |
| 29 Jan 2021 | 02:08 UTC | Mercury at perihelion | Capricornus |
| 29 Jan 2021 | 16:28 UTC | The Moon at aphelion | Leo |
February 2021
| 02 Feb 2021 | 21:34 UTC | Asteroid 18 Melpomene at opposition | Cancer |
| 03 Feb 2021 | 19:02 UTC | The Moon at perigee | Virgo |
| 04 Feb 2021 | 17:37 UTC | Moon at Last Quarter | Libra |
| 08 Feb 2021 | – | α-Centaurid meteor shower | Centaurus |
| 08 Feb 2021 | 13:41 UTC | Mercury at inferior solar conjunction | Aquarius |
| 10 Feb 2021 | 09:48 UTC | The Moon at perihelion | Capricornus |
| 10 Feb 2021 | 11:11 UTC | Conjunction of the Moon and Saturn | Capricornus |
| 11 Feb 2021 | 19:06 UTC | New Moon | Capricornus |
| 18 Feb 2021 | 10:21 UTC | The Moon at apogee | Aries |
| 18 Feb 2021 | 22:45 UTC | Conjunction of the Moon and Mars | Aries |
| 19 Feb 2021 | 18:48 UTC | Moon at First Quarter | Taurus |
| 20 Feb 2021 | 08:36 UTC | Venus at aphelion | Capricornus |
| 22 Feb 2021 | 16:46 UTC | Asteroid 29 Amphitrite at opposition | Leo |
| 24 Feb 2021 | – | Mercury reaches highest point in morning sky | Capricornus |
| 27 Feb 2021 | 08:17 UTC | Full Moon | Leo |
March 2021
| 01 Mar 2021 | 03:57 UTC | The Moon at aphelion | Virgo |
| 02 Mar 2021 | 05:17 UTC | The Moon at perigee | Virgo |
| 02 Mar 2021 | 14:10 UTC | Mercury at dichotomy | Capricornus |
| 04 Mar 2021 | 23:58 UTC | Asteroid 4 Vesta at opposition | Leo |
| 05 Mar 2021 | 06:49 UTC | Conjunction of Jupiter and Mercury | Capricornus |
| 06 Mar 2021 | 01:30 UTC | Moon at Last Quarter | Ophiuchus |
| 06 Mar 2021 | 09:48 UTC | Mercury at greatest elongation west | Capricornus |
| 09 Mar 2021 | 22:58 v | Conjunction of the Moon and Saturn | Capricornus |
| 10 Mar 2021 | 15:37 UTC | Conjunction of the Moon and Jupiter | Capricornus |
| 11 Mar 2021 | 00:02 UTC | Neptune at solar conjunction | Aquarius |
| 11 Mar 2021 | 01:02 UTC | Conjunction of the Moon and Mercury | Capricornus |
| 11 Mar 2021 | 02:01 UTC | The Moon at perihelion | Capricornus |
| 13 Mar 2021 | 10:21 UTC | New Moon | Aquarius |
| 14 Mar 2021 | 01:45 UTC | Mercury at aphelion | Aquarius |
| 14 Mar 2021 | – | γ-Normid meteor shower | Norma |
| 18 Mar 2021 | 05:02 UTC | The Moon at apogee | Aries |
| 19 Mar 2021 | 17:47 UTC | Conjunction of the Moon and Mars | Taurus |
| 20 Mar 2021 | 09:22 UTC | March equinox | Pisces |
| 21 Mar 2021 | 14:41 UTC | Moon at First Quarter | Gemini |
| 24 Mar 2021 | – | 10P/Tempel at perihelion | Aquarius |
| 26 Mar 2021 | 06:20 UTC | Venus at superior solar conjunction | Pisces |
| 27 Mar 2021 | 14:43 UTC | 136472 Makemake at opposition | Coma Berenices |
| 28 Mar 2021 | 19:48 BST | Full Moon | Virgo |
| 29 Mar 2021 | 03:39 BST | Venus at greatest brightness | Cetus |
| 29 Mar 2021 | 20:10 BST | Conjunction of Mercury and Neptune | Aquarius |
| 30 Mar 2021 | 07:15 BST | The Moon at perigee | Virgo |
| 30 Mar 2021 | 23:40 BST | The Moon at aphelion | Libra |
April 2021
| 04 Apr 2021 | 11:02 BST | Moon at Last Quarter | Sagittarius |
| 05 Apr 2021 | 08:10 BST | Asteroid 9 Metis at opposition | Virgo |
| 06 Apr 2021 | 09:30 BST | Conjunction of the Moon and Saturn | Capricornus |
| 07 Apr 2021 | 08:18 BST | Conjunction of the Moon and Jupiter | Capricornus |
| 07 Apr 2021 | 13:05 BST | 1 Ceres at solar conjunction | Cetus |
| 09 Apr 2021 | 09:32 BST | The Moon at perihelion | Aquarius |
| 12 Apr 2021 | 03:31 BST | New Moon | Pisces |
| 14 Apr 2021 | 04:04 BST | 136199 Eris at solar conjunction | Cetus |
| 14 Apr 2021 | 18:45 BST | The Moon at apogee | Taurus |
| 17 Apr 2021 | 13:08 BST | Conjunction of the Moon and Mars | Taurus |
| 17 Apr 2021 | 13:10 BST | Lunar occultation of Mars | Taurus |
| 18 Apr 2021 | 01:04 BST | 136108 Haumea at opposition | Bootes |
| 19 Apr 2021 | 02:36 BST | Mercury at superior solar conjunction | Aries |
| 20 Apr 2021 | 07:59 BST | Moon at First Quarter | Cancer |
| 22 Apr 2021 | – | Lyrid meteor shower | Hercules |
| 23 Apr 2021 | – | π-Puppid meteor shower | Puppis |
| 27 Apr 2021 | 02:23 BST | Mercury at perihelion | Aries |
| 27 Apr 2021 | 04:32 BST | Full Moon | Libra |
| 27 Apr 2021 | 16:22 BST | The Moon at perigee | Libra |
| 28 Apr 2021 | 20:29 BST | Conjunction of Ceres and Eris | Cetus |
| 29 Apr 2021 | 04:32 BST | The Moon at aphelion | Scorpius |
| 30 Apr 2021 | 20:55 BST | Uranus at solar conjunction | Aries |
May 2021
| 03 May 2021 | 17:59 BST | Conjunction of the Moon and Saturn | Capricornus |
| 03 May 2021 | 20:50 BST | Moon at Last Quarter | Capricornus |
| 04 May 2021 | 22:03 BST | Conjunction of the Moon and Jupiter | Aquarius |
| 06 May 2021 | – | η-Aquariid meteor shower | Aquarius |
| 08 May 2021 | – | η-Lyrid meteor shower | Lyra |
| 09 May 2021 | 11:25 BST | The Moon at perihelion | Pisces |
| 11 May 2021 | 20:00 BST | New Moon | Aries |
| 11 May 2021 | 22:53 BST | The Moon at apogee | Aries |
| 12 May 2021 | 06:13 BST | Mercury at dichotomy | Taurus |
| 12 May 2021 | 23:04 BST | Conjunction of the Moon and Venus | Taurus |
| 13 May 2021 | – | Mercury reaches highest point in evening sky | Taurus |
| 13 May 2021 | 18:58 BST | Conjunction of the Moon and Mercury | Taurus |
| 16 May 2021 | 05:47 BST | Conjunction of the Moon and Mars | Gemini |
| 17 May 2021 | 09:04 BST | Mercury at greatest elongation east | Taurus |
| 19 May 2021 | 20:13 BST | Moon at First Quarter | Leo |
| 26 May 2021 | 02:49 BST | The Moon at perigee | Libra |
| 26 May 2021 | 12:14 BST | Full Moon | Scorpius |
| 26 May 2021 | 12:18 BST | Total lunar eclipse | Scorpius |
| 27 May 2021 | 20:46 BST | The Moon at aphelion | Ophiuchus |
| 29 May 2021 | 06:20 BST | Conjunction of Venus and Mercury | Taurus |
| 31 May 2021 | 02:18 BST | Conjunction of the Moon and Saturn | Capricornus |
June 2021
| 01 Jun 2021 | 10:00 BST | Conjunction of the Moon and Jupiter | Aquarius |
| 02 Jun 2021 | 08:25 BST | Moon at Last Quarter | Aquarius |
| 04 Jun 2021 | 08:10 BST | Asteroid 63 Ausonia at opposition | Scorpius |
| 04 Jun 2021 | 18:43 BST | Conjunction of Uranus and Ceres | Cetus |
| 08 Jun 2021 | 03:27 BST | The Moon at apogee | Aries |
| 09 Jun 2021 | 04:42 BST | The Moon at perihelion | Taurus |
| 10 Jun 2021 | 02:01 BST | Mercury at aphelion | Taurus |
| 10 Jun 2021 | 11:42 BST | Annular solar eclipse | Taurus |
| 10 Jun 2021 | 11:53 BST | New Moon | Taurus |
| 10 Jun 2021 | – | Daytime Arietid meteor shower | Aries |
| 11 Jun 2021 | 02:05 BST | Mercury at inferior solar conjunction | Taurus |
| 12 Jun 2021 | 07:43 BST | Conjunction of the Moon and Venus | Gemini |
| 12 Jun 2021 | 18:34 BST | Venus at perihelion | Gemini |
| 13 Jun 2021 | 20:53 BST | Conjunction of the Moon and Mars | Cancer |
| 18 Jun 2021 | 04:54 BST | Moon at First Quarter | Virgo |
| 18 Jun 2021 | – | 15P/Finlay at perigee | Pisces |
| 21 Jun 2021 | 04:16 BST | June solstice | Taurus |
| 23 Jun 2021 | 10:54 BST | The Moon at perigee | Ophiuchus |
| 24 Jun 2021 | 19:40 BST | Full Moon | Sagittarius |
| 25 Jun 2021 | 06:47 BST | The Moon at aphelion | Sagittarius |
| 27 Jun 2021 | 10:27 BST | Conjunction of the Moon and Saturn | Capricornus |
| 27 Jun 2021 | – | June Bootid meteor shower | Bootes |
| 28 Jun 2021 | 19:41 BST | Conjunction of the Moon and Jupiter | Aquarius |
July 2021
| 01 Jul 2021 | 22:11 BST | Moon at Last Quarter | Cetus |
| 05 Jul 2021 | 05:01 BST | Mercury at greatest elongation west | Taurus |
| 05 Jul 2021 | 15:46 BST | The Moon at apogee | Taurus |
| 05 Jul 2021 | 23:27 BST | The Earth at aphelion | Pisces |
| 07 Jul 2021 | – | 15P/Finlay reaches its brightest | Aries |
| 08 Jul 2021 | 05:39 BST | Conjunction of the Moon and Mercury | Taurus |
| 09 Jul 2021 | 18:40 BST | Mercury at dichotomy | Taurus |
| 10 Jul 2021 | 02:17 BST | New Moon | Gemini |
| 10 Jul 2021 | 02:49 BST | The Moon at perihelion | Gemini |
| 11 Jul 2021 | – | Mercury reaches highest point in morning sky | Taurus |
| 12 Jul 2021 | 10:10 BST | Conjunction of the Moon and Venus | Leo |
| 12 Jul 2021 | 11:11 BST | Conjunction of the Moon and Mars | Leo |
| 13 Jul 2021 | 01:25 BST | Mars at aphelion | Leo |
| 13 Jul 2021 | 08:06 BST | Conjunction of Venus and Mars | Leo |
| 14 Jul 2021 | – | 15P/Finlay at perihelion | Taurus |
| 17 Jul 2021 | 11:11 BST | Moon at First Quarter | Virgo |
| 18 Jul 2021 | 07:20 BST | 134340 Pluto at opposition | Sagittarius |
| 18 Jul 2021 | 22:34 BST | Asteroid 6 Hebe at opposition | Aquila |
| 21 Jul 2021 | 11:24 BST | The Moon at perigee | Ophiuchus |
| 23 Jul 2021 | 14:44 BST | The Moon at aphelion | Sagittarius |
| 24 Jul 2021 | 01:39 BST | Mercury at perihelion | Gemini |
| 24 Jul 2021 | 03:37 BST | Full Moon | Capricornus |
| 24 Jul 2021 | 17:38 BST | Conjunction of the Moon and Saturn | Capricornus |
| 26 Jul 2021 | 02:21 BST | Conjunction of the Moon and Jupiter | Aquarius |
| 28 Jul 2021 | – | Piscis Austrinid meteor shower | Piscis Austrinus |
| 30 Jul 2021 | – | Southern δ-Aquariid meteor shower | Aquarius |
| 30 Jul 2021 | – | α-Capricornid meteor shower | Capricornus |
| 30 Jul 2021 | 20:10 BST | Asteroid 12 Victoria at opposition | Aquila |
| 31 Jul 2021 | 14:16 BST | Moon at Last Quarter | Aries |
August 2021
| 01 Aug 2021 | 14:54 BST | Mercury at superior solar conjunction | Cancer |
| 02 Aug 2021 | 07:01 BST | Saturn at opposition | Capricornus |
| 02 Aug 2021 | 08:35 BST | The Moon at apogee | Taurus |
| 08 Aug 2021 | 14:50 BST | New Moon | Cancer |
| 09 Aug 2021 | 19:40 BST | The Moon at perihelion | Leo |
| 10 Aug 2021 | 01:42 BST | Conjunction of the Moon and Mars | Leo |
| 11 Aug 2021 | 07:59 BST | Conjunction of the Moon and Venus | Virgo |
| 12 Aug 2021 | – | Perseid meteor shower | Perseus |
| 12 Aug 2021 | 22:34 BST | Asteroid 349 Dembowska at opposition | Piscis Austrinus |
| 15 Aug 2021 | 16:20 BST | Moon at First Quarter | Libra |
| 17 Aug 2021 | 10:15 BST | The Moon at perigee | Ophiuchus |
| 18 Aug 2021 | – | κ-Cygnid meteor shower | Draco |
| 19 Aug 2021 | 05:06 BST | Conjunction of Mercury and Mars | Leo |
| 19 Aug 2021 | 20:10 BST | Asteroid 43 Ariadne at opposition | Aquarius |
| 20 Aug 2021 | 01:16 BST | Jupiter at opposition | Capricornus |
| 20 Aug 2021 | 23:15 BST | Conjunction of the Moon and Saturn | Capricornus |
| 21 Aug 2021 | 00:31 BST | The Moon at aphelion | Capricornus |
| 22 Aug 2021 | 05:56 BST | Conjunction of the Moon and Jupiter | Capricornus |
| 22 Aug 2021 | 13:02 BST | Blue Moon | Aquarius |
| 24 Aug 2021 | 15:22 BST | Asteroid 89 Julia at opposition | Aquarius |
| 30 Aug 2021 | 03:22 BST | The Moon at apogee | Taurus |
| 30 Aug 2021 | 08:13 BST | Moon at Last Quarter | Taurus |
September 2021
| 01 Sep 2021 | – | Aurigid meteor shower | Auriga |
| 01 Sep 2021 | – | Mercury reaches highest point in evening sky | Virgo |
| 06 Sep 2021 | 01:17 BST | Mercury at aphelion | Virgo |
| 07 Sep 2021 | 01:52 BST | New Moon | Leo |
| 08 Sep 2021 | 21:18 BST | Conjunction of the Moon and Mercury | Virgo |
| 09 Sep 2021 | 01:17 BST | The Moon at perihelion | Virgo |
| 09 Sep 2021 | – | September ε-Perseid meteor shower | Perseus |
| 10 Sep 2021 | 03:08 BST | Conjunction of the Moon and Venus | Virgo |
| 10 Sep 2021 | – | 4P/Faye at perihelion | Taurus |
| 11 Sep 2021 | 11:03 BST | The Moon at perigee | Libra |
| 11 Sep 2021 | 20:10 BST | Asteroid 2 Pallas at opposition | Pisces |
| 13 Sep 2021 | 21:39 BST | Moon at First Quarter | Ophiuchus |
| 13 Sep 2021 | 22:44 BST | Mercury at greatest elongation east | Virgo |
| 14 Sep 2021 | 10:05 BST | Neptune at opposition | Aquarius |
| 17 Sep 2021 | 03:33 BST | Conjunction of the Moon and Saturn | Capricornus |
| 18 Sep 2021 | 03:49 BST | Mercury at dichotomy | Virgo |
| 18 Sep 2021 | 07:54 BST | Conjunction of the Moon and Jupiter | Capricornus |
| 18 Sep 2021 | 17:44 BST | The Moon at aphelion | Aquarius |
| 20 Sep 2021 | 12:46 BST | Mars at apogee | Virgo |
| 21 Sep 2021 | 00:55 BST | Full Moon | Pisces |
| 22 Sep 2021 | 20:06 BST | September equinox | Virgo |
| 26 Sep 2021 | 22:43 BST | The Moon at apogee | Taurus |
| 27 Sep 2021 | – | Daytime Sextantid meteor shower | Sextans |
| 29 Sep 2021 | 02:57 BST | Moon at Last Quarter | Gemini |
| 30 Sep 2021 | 15:50 BST | 136472 Makemake at solar conjunction | Coma Berenices |
October 2021
| 02 Oct 2021 | 03:22 BST | Asteroid 40 Harmonia at opposition | Cetus |
| 03 Oct 2021 | 01:43 BST | Venus at aphelion | Libra |
| 05 Oct 2021 | – | October Camelopardalid meteor shower | Draco |
| 06 Oct 2021 | 12:05 BST | New Moon | Virgo |
| 08 Oct 2021 | 05:19 BST | Mars at solar conjunction | Virgo |
| 08 Oct 2021 | 16:45 BST | The Moon at perihelion | Libra |
| 08 Oct 2021 | 18:27 BST | The Moon at perigee | Libra |
| 08 Oct 2021 | – | Draconid meteor shower | Draco |
| 09 Oct 2021 | 17:11 BST | Mercury at inferior solar conjunction | Virgo |
| 09 Oct 2021 | 19:35 BST | Conjunction of the Moon and Venus | Scorpius |
| 10 Oct 2021 | – | Southern Taurid meteor shower | Cetus |
| 11 Oct 2021 | – | δ-Aurigid meteor shower | Auriga |
| 13 Oct 2021 | 04:25 BST | Moon at First Quarter | Sagittarius |
| 14 Oct 2021 | 08:09 BST | Conjunction of the Moon and Saturn | Capricornus |
| 15 Oct 2021 | 11:03 BST | Conjunction of the Moon and Jupiter | Capricornus |
| 17 Oct 2021 | 17:31 BST | 136199 Eris at opposition | Cetus |
| 18 Oct 2021 | 02:12 BST | The Moon at aphelion | Aquarius |
| 18 Oct 2021 | – | ε-Geminid meteor shower | Gemini |
| 20 Oct 2021 | 00:56 BST | Mercury at perihelion | Virgo |
| 20 Oct 2021 | 15:57 BST | Full Moon | Pisces |
| 21 Oct 2021 | – | Orionid meteor shower | Orion |
| 21 Oct 2021 | 23:21 BST | 136108 Haumea at solar conjunction | Bootes |
| 23 Oct 2021 | 23:32 BST | Mercury at dichotomy | Virgo |
| 24 Oct 2021 | – | Leonis Minorid meteor shower | Leo Minor |
| 24 Oct 2021 | 16:28 BST | The Moon at apogee | Taurus |
| 25 Oct 2021 | – | Mercury reaches highest point in morning sky | Virgo |
| 25 Oct 2021 | 04:35 BST | Mercury at greatest elongation west | Virgo |
| 28 Oct 2021 | 15:22 BST | Venus at dichotomy | Ophiuchus |
| 28 Oct 2021 | 21:05 BST | Moon at Last Quarter | Cancer |
| 29 Oct 2021 | 15:43 BST | Venus at greatest elongation east | Ophiuchus |
November 2021
| 02 Nov 2021 | – | 67P/Churyumov-Gerasimenko at perihelion | Gemini |
| 03 Nov 2021 | 18:39 UTC | Conjunction of the Moon and Mercury | Virgo |
| 04 Nov 2021 | 21:15 UTC | New Moon | Libra |
| 04 Nov 2021 | 23:43 UTC | Uranus at opposition | Aries |
| 05 Nov 2021 | 22:17 UTC | The Moon at perigee | Libra |
| 06 Nov 2021 | 17:21 UTC | The Moon at perihelion | Ophiuchus |
| 07 Nov 2021 | – | 67P/Churyumov-Gerasimenko reaches its brightest | Gemini |
| 08 Nov 2021 | 05:20 UTC | Conjunction of the Moon and Venus | Sagittarius |
| 08 Nov 2021 | 05:28 UTC | Lunar occultation of Venus | Sagittarius |
| 10 Nov 2021 | 14:24 UTC | Conjunction of the Moon and Saturn | Capricornus |
| 11 Nov 2021 | 12:46 UTC | Moon at First Quarter | Capricornus |
| 11 Nov 2021 | 17:17 UTC | Conjunction of the Moon and Jupiter | Capricornus |
| 12 Nov 2021 | – | Northern Taurid meteor shower | Taurus |
| 12 Nov 2021 | – | 67P/Churyumov-Gerasimenko at perigee | Cancer |
| 17 Nov 2021 | 06:51 UTC | The Moon at aphelion | Pisces |
| 17 Nov 2021 | – | Leonid meteor shower | Leo |
| 19 Nov 2021 | 08:58 UTC | Full Moon | Taurus |
| 19 Nov 2021 | 09:03 UTC | Partial lunar eclipse | Taurus |
| 21 Nov 2021 | 02:12 UTC | The Moon at apogee | Taurus |
| 21 Nov 2021 | – | α-Monocerotid meteor shower | Canis Minor |
| 27 Nov 2021 | 06:29 UTC | 1 Ceres at opposition | Taurus |
| 27 Nov 2021 | 12:28 UTC | Moon at Last Quarter | Leo |
| 28 Nov 2021 | – | November Orionid meteor shower | Orion |
| 29 Nov 2021 | 04:20 UTC | Mercury at superior solar conjunction | Scorpius |
December 2021
| 02 Dec 2021 | – | Pheonicid meteor shower | Phoenix |
| 02 Dec 2021 | 23:34 UTC | Mercury at aphelion | Ophiuchus |
| 03 Dec 2021 | 00:28 UTC | Conjunction of the Moon and Mars | Libra |
| 04 Dec 2021 | 07:33 UTC | Total solar eclipse | Ophiuchus |
| 04 Dec 2021 | 07:43 UTC | New Moon | Ophiuchus |
| 04 Dec 2021 | 10:04 UTC | The Moon at perigee | Ophiuchus |
| 05 Dec 2021 | 09:23 UTC | The Moon at perihelion | Sagittarius |
| 06 Dec 2021 | – | December φ-Cassiopeid meteor shower | Andromeda |
| 07 Dec 2021 | 00:48 UTC | Conjunction of the Moon and Venus | Sagittarius |
| 07 Dec 2021 | – | Puppid-Velid meteor shower | Vela |
| 07 Dec 2021 | 16:07 UTC | Venus at greatest brightness | Sagittarius |
| 08 Dec 2021 | 01:50 UTC | Conjunction of the Moon and Saturn | Capricornus |
| 09 Dec 2021 | – | Monocerotid meteor shower | Monoceros |
| 09 Dec 2021 | 06:11 UTC | Conjunction of the Moon and Jupiter | Capricornus |
| 10 Dec 2021 | 16:46 UTC | Asteroid 44 Nysa at opposition | Taurus |
| 11 Dec 2021 | 01:36 UTC | Moon at First Quarter | Aquarius |
| 12 Dec 2021 | – | σ-Hydrid meteor shower | Hydra |
| 13 Dec 2021 | 06:45 UTC | Conjunction of Venus and Pluto | Sagittarius |
| 14 Dec 2021 | – | Geminid meteor shower | Gemini |
| 14 Dec 2021 | – | Venus reaches highest point in evening sky | Ophiuchus |
| 16 Dec 2021 | – | Comae Berenicid meteor shower | Leo |
| 18 Dec 2021 | 02:14 UTC | The Moon at apogee | Taurus |
| 18 Dec 2021 | 06:58 UTC | The Moon at aphelion | Taurus |
| 19 Dec 2021 | 04:36 UTC | Full Moon | Taurus |
| 19 Dec 2021 | – | December Leonis Minorid meteor shower | Leo Minor |
| 21 Dec 2021 | 15:45 UTC | December solstice | Sagittarius |
| 22 Dec 2021 | 02:48 UTC | Conjunction of Venus and Pluto | Sagittarius |
| 22 Dec 2021 | – | Ursid meteor shower | Ursa Minor |
| 27 Dec 2021 | 02:24 UTC | Moon at Last Quarter | Virgo |
| 29 Dec 2021 | 01:02 UTC | Conjunction of Venus and Mercury | Sagittarius |
| 30 Dec 2021 | 14:18 UTC | Conjunction of Mercury and Pluto | Sagittarius |
| 31 Dec 2021 | 19:53 UTC | Lunar occultation of Mars | Ophiuchus |
| 31 Dec 2021 | 20:13 UTC | Conjunction of the Moon and Mars | Ophiuchus |
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