-   December 21, 2020 - 18:27 (UTC)   -

The last months of 2020 Jupiter and Saturn have dominated the night sky, being an unmistakable visual reference. Now, as the year ends and as their positions approach twilight, they will end up offering a final show: the Great Conjunction, a "Gathering of Giants." Their closest apparent approach, on the line of visual projection from Earth, will occur on December 21 at 18:27 (UTC), at which time the angular separation of these gas giants will be only 6.11 minutes arc. The image that we will have in the sky will be the one contemplated by the simulation of the attached figure (click on the image to enlarge), with an unprecedented dance of satellites in this reduced visual field.

A conjunction of Jupiter and Saturn is not exceptional, but it is unusual. It can occur 4 or 5 times every 100 years. This time it is really special because his lineup is very close. As can be seen in the attached image, (which collects approximations for 2 centuries), another similar conjunction will not occur until the year 2080. The previous one of these characteristics took place on July 16, 1623.

But not only December 21 can be of interest to astrophotographers, amateurs and astronomers in general. The observations of days before and immediately afterwards will also be interesting, in which both planets will combine their approach until reaching the maximum. (See also next image).

To facilitate and channel the desirable activities on the occasion of this particular event, the entities listed on the right bank have joined forces in order to join forces and offer means, carry out actions, including dissemination, and encourage the participation of professionals and amateurs in the same. It is intended that these pages collect and be a reference for these activities, in addition to serving as a communication channel between all Pro-Am who can and wish to participate in this "Giants Meeting".


- Collaborating observatories

  • on-line broadcasts
    (provisional advance - information will be updated).

  • There will be a centralized session through the Zoom platform (12.21.2020 - 6:30 PM CET [5:30 PM UT]), with simultaneous connections to the different observatories.

  • You can follow the session on the FAAE YouTube channel.

  • You can also independently access the different channels of the related observatories.


- Planetario de Pamplona && Red Astronavarra Sarea
Observación y retransmisión en directo - Canal YouTube.

Al tiempo se proyectará sobre el edificio del planetario la noche del 21 de diciembre.
Contacto: Fernando Jáuregui <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Observatorio de Guirguillano (Navarra):
Observación y retransmisión. Canal YouTube
Contacto: Iñaki Ordóñez-Etxeberria <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Observatorio del Aula Espazio Gela (Bilbao):
Observación y transmisión en directo. Días previos y el 21D.

Telescopio reflector de 20" y refractor de 12".

Contacto: Santiago Pérez-Hoyos <This email address is being protected from spambots. You need JavaScript enabled to view it.> y Ricardo Hueso <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Observatorio del Museo de las Ciencias de CLM && AstroCuenca (Cuenca)
Observación y transmisión en directo. Días previos y el 21D.
Telescopio 16" + CCD: QHY90A y QH5-III. Canal YouTube AstroCuenca - Canal YouTube MCCM.
Contacto: J. Álvaro <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Sociedad Malagueña de Astronomía (Málaga).
Observación y transmisión en directo. Canal YouTube.
Telescopio C11 && ZWO ASI224MC.
Contacto: Juan Carlos Aznar <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Observatorio Astronómico de la Hita (La Puebla de Almoradiel - Toledo).
Observación y transmisión en directo. Canal YouTube.
Contacto: Faustino Organero <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Complejo Astronómico Municipio de El Espinar -CAME - (Segovia) - Asoc. Hespérides
Observación y transmisión en directo. Canal de Youtube
Contacto: Juanjo García <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Astróbriga (Ciudad Rodrigo - Salamanca)
Observación y transmisión en directo. Canal de Youtube.
Telescopio C SCT 9.25 && ZWO ASI 290MC

Contacto: Óscar Corvo <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Observatorio Astronómico de la Sagra - (Puebla de Don Fabrique - Granada)
Telescopio C14 (f/2.1) - QHY174. Canal YouTube
Contacto: Emilio J. García <This email address is being protected from spambots. You need JavaScript enabled to view it.>

- Observatorio Lago Alqueva (OLA) - Monsaraz (Portugal) - 17:30 h UT
Canal web

- Nayoro Observatory of Japan - 08:30 h UT
Transmisión en streaming. Canal YouTube.
Telescopio 1.600 mm DF 19.200 mm

- Nagoya City Science Museum of Japan - 08:15 h UT
Telescope and camera: 20-cm refracting telescope, F/10, EOS R
URL of broadcasting: https://www.youtube.com/c/NagoyaCityScienceMuseum

Koyama Astronomical Observatory of Kyoto Sangyo University - 08:30 UT
Telescope and camera: 12-cm refracting telescope, digital camera or CMOS camera
URL of broadcasting: https://www.youtube.com/c/KSUKoyamaTenmondai

Akashi Municipal Planetarium - 08:30 UT
URL of broadcasting: https://www.youtube.com/channel/UCEEFdpOwKKORoc8SRMCtROg

Minami-aso Luna Observatory - 08:30 UT
URL of broadcasting: https://www.youtube.com/channel/UCx3tewSFj03nl1MEk3Zl3-A

- Virtual Telescope Project of Italy - 16:30 h UT

- Observatorio Colegio San Antonio - (Puerto Rico) - 21:00 h UT
Telescopio Celestron Edge HD Schmidt-Cassegrain 280 mm && Orion Sky Quest XX 16" + ZWO ASI 120MC
Canal webinar/zoom
Contacto: Merry Manso <This email address is being protected from spambots. You need JavaScript enabled to view it.>


  • If you have an observatory (amateur / professional), you are going to observe the conjunction of Jupiter and Saturn on December 21st and you plan to broadcast the observation through an online channel, you can register your activity here and we will broadcast it in our centralized session of collaborating observatories, within our technical possibilities.


- Amateurs / Astrophotographers 

  • The joint vision of Jupiter and Saturn is an inspiring image, a true Gathering of Giants capable of raising our gaze towards the sky. We would like to have your observation of both planets. Whether you are a fan of deep sky astrophotography, or if you prefer planetary photography or even night landscapes, we invite you to observe these planets during the next few nights and send us your observations to the gallery of photographs that we are preparing.

  • We are especially interested in the photographs that show the conjunction on different dates as both planets gradually get closer to each other until they end only 6 minutes apart on December 21, to progressively move away from that moment. If you wish to send us your images, please send your photographs to J. Álvaro, <This email address is being protected from spambots. You need JavaScript enabled to view it.>, together with your name and data of interest, including the date / time of capture, (we recommend also including an identifying watermark). The images will be available on this web page and, if they are very numerous, we will make a complete gallery and another of selected images. 


© Giorgia Hofer

Conjunction video (Maarten Roos - VOC for the EPSC 2021)


  • Observation of Jupiter and Saturn with binoculars and telescope.

In this document.pdf you will be able to find useful information for observing the two planets and their satellites, as well as useful tips for recording observations and a file to record them. It is also recommended to attend the workshops and talks that have been organized to celebrate the event.

  • Tips for observing Jupiter and Saturn with the naked eye.

From the end of November to the end of December 2020, it is very easy to locate these two giant planets of the Solar System. Looking at sunset towards the southwest, where the Sun has set on the horizon ... (read more)

Jupiter and Saturn closer than Algedi and Dabih in Capricorn. They will get as close as the double Algedi optics, whose two stars are 6.6 arc minutes apart, just wait until December 21. (Click on the image to enlarge).



- WorkShops - (View recorded sessions - in Spanish)

  • Friday, December 11 - 18:00 h
    • planetary drawing workshop, by Leonor Ana Hernández (AstroHita)

Intended for all beginners and advanced astronomers of all ages. Its purpose is to help improve as observers and obtain a personal record of these bodies in the Solar System. In this workshop we will learn how to organize an optimal observation of the planets to make the most of the night, we will see the necessary materials for their registration by hand and the most used techniques to ensure that our final work is faithful to what we observe.

How to optimize the night of observation? What materials are essential? What details to look at? We will learn how we should apply the pencil or use the eraser, as well as we will know some tools to get the fine details. The important thing is to bring us an unforgettable visual memory and put what we have observed on paper. The result is always surprising.

  • Monday, December 14 - 18:00 h 
    • planetary astrophotography

 "The observation of the giant planets and the conjunction of 21D", by Santiago Pérez-Hoyos (UPV/EHU)

In this workshop we will interactively review some essential tools for observing and processing images of the giant planets, Jupiter and Saturn, in order to prepare for the next conjunction on December 21

"The Great Conjunction", by Carolina Clavijo (ApEA)

From today until next December 21, 2020, we are going to study the great conjunction. We will see how the planets move in the sky, and specifically how Jupiter "approaches" Saturn. This will not happen again for 60 years.



- Outreach - [View recorded session - in Spanish] 

  • Friday, December 18 - 18:00 h  
    • conferences

"Giants of the Solar System: Exotic and immense sculptors of our planetary system", by Ricardo Hueso Alonso (UPV/EHU)

"On the hunt for the space Snark. On Exploring the Planetary Oceans with Empty Maps", by Olga Prieto Ballesteros (CAB-INTA-CSIC)

    • round table and debate

Miguel Ángel López Valverde - IAA
Amelia Ortiz Gil - IAU
Ricardo Hueso Alonso - UPV/EHU
Olga Prieto Ballesteros - CAB-INTA-CSIC
modera: Mabel Angulo


- Poster and Resources


  • If you participate or collaborate with activities of the event and want to use the poster designed for the occasion, you can download it by clicking on the image.


What is a planetary conjunction?

A conjunction is an astronomical event that occurs when two stars have a very small apparent distance between them when they are observed from Earth. The conjunctions occur between the planets, the Moon and the Sun, because they are objects that gradually change their position in the sky, either by their own movement or by the movement of the Earth. Conjunctions are relatively frequent phenomena because all objects in the Solar System follow movements apparently along a line in the sky, the same for all, which we call "ecliptic." This is because all the planets and objects in the Solar System are approximately in one plane, as a consequence of their formation process, about 4,500 million years ago, when the nebula of dust and gas that gave us origin contracted by gravity. In the case of planetary conjunctions it is necessary that the Earth and the two planets that are part of the conjunction are aligned.

Does the fact that they look very close together in the sky mean that they also get closer to each other?

No. The approximation between objects in conjunction is a visual phenomenon and does not imply that both objects are close to each other. In this conjunction the physical distance between Jupiter and Saturn reached its minimum distance on October 12, 2020, with a separation of almost 730 million kilometers. However, the greatest visual proximity between the two planets will occur on December 21. This is because not only the movements of Jupiter and Saturn come into play, but also the translational movement of the Earth and its alignment with the other two planets.

When was this conjunction last seen, and when will it be seen again?

The conjunction between Jupiter and Saturn is periodic, and occurs approximately every 20 years. However, the last time there was a chance to see such a close conjunction between the two planets was in 1623. To see a conjunction at such a short distance again, we will have to wait until 2080.

- relative positions from December 15 to December 27 -

How can I observe the conjunction?

Jupiter and Saturn are bright planets that can be seen as bright stars without the need for optical instruments. The days leading up to December 21, the two planets can be observed with the naked eye in a very close position in the sky. On December 21 it will be convenient to use binoculars to distinguish them from each other. If you have a simple telescope, you will be able to distinguish, in addition to the planets, the rings of Saturn and the largest of the moons of both planets.

Where do I have to look?

The conjunction between Jupiter and Saturn will be visible at dusk with both objects at elevations of about 20 degrees above the horizon at the beginning of the night. Looking west, both planets can be seen as two very close bright stars or a single, very bright point. With binoculars, the distance between both objects will be observed well and some of their satellites can be seen.

And if it's cloudy, will I be able to see it before or after December 21?

Yes, the conjunction can be observed the days before and after, although the distance between Jupiter and Saturn will not be so small. In any case, if atmospheric conditions do not allow us to observe the conjunction from our location, we can resort to online observation of the event. For this, from this same page we will facilitate the transmission of the conjunction from different professional and amateur observatories.

I am Pisces, can this planetary alignment affect me in any way?

Yes. If you observe the conjunction with binoculars you will see how celestial mechanics works live, and you will see in detail this special and beautiful event that astronomy gives us. You will also observe that the firmament is already wonderful enough that it is totally unnecessary to invent or believe in unfounded astrological ideas. It also works if you are a Sagittarius.


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