This Monday (21st), there is an alignment between Jupiter and Saturn, one of the most awaited astronomical events of 2020. The phenomenon can be seen from anywhere in Brazil with the naked eye, as long as the weather conditions are favorable.
During the “great conjunction”, as the encounter is known, the two celestial bodies will be aligned in such a way that they will appear to form a kind of double disc, making a great spectacle in the night sky.
The total alignment began on Wednesday (16), and can be seen initially in the regions closest to the Equator, and runs until Christmas Day. But its peak will occur on the 21st, the date that marks the summer solstice in the Southern Hemisphere.
Anyone who misses the chance to see the conjunction of Jupiter and Saturn in 2020 will need to wait until 2080 to have an opportunity with similar conditions. And after the latter, such a visible alignment will only happen around 2400.
A little of history
Also nicknamed “star of Bethlehem” and “Christmas kiss”, due to the time when it will happen this time, the approximation between the two largest planets in the Solar System occurs every 19.85 years. But they don’t always get as close to each other as they do now.
The last time Jupiter and Saturn had an alignment as close as that of 2020 was in 1623, that is, 400 years ago. And in conditions similar to those of now, taking place at night, the most recent event took place in 1226, still during the Middle Ages.
This phenomenon marks the time it takes the two gas giants to find themselves aligned, after completing the orbit around the Sun. While Jupiter travels in “just” 11.86 years, Saturn takes a little longer to finish the journey: 29.4 years.
It is noteworthy that both will not be on the same plane during the event or as close as it may seem to be observing from Earth. It’s all about perspective. They will be at different points in the sky and will be approximately 700 million kilometers apart.
How to observe the conjunction
On the 21st, about an hour after sunset, it will be possible to see the conjunction between Jupiter and Saturn. To do so, look towards the west and locate the alignment formed at a lower point in the sky, characterized by two objects of great brightness.
Larger and brighter, Jupiter will be on the left, showing a whitish luminosity. Saturn can be seen on the right, showing an orange glow.
For a wider view, the ideal is to be in an open place, without buildings and trees nearby, in addition to having little artificial light. It is also essential that the sky has no clouds at the time of the phenomenon.
If you have a telescope, even if it is simpler, you can observe the alignment with a broader level of detail, seeing the four largest moons of Jupiter orbiting the planet, for example. Even binoculars offer some advantages.
On YouTube, you will be able to follow a live broadcast by the Planetarium Rubens de Azevedo, in Ceará. The live will feature comments from Professor Dr. Ednardo Rodrigues, from the Seara Astronomy Group (GAS Interstellar) team.