Nearly 800 years ago, in 1226, two planets were visibly “aligned” in the night sky. It was the conjunction of Jupiter and Saturn. In a rare case, they appeared extremely close together, 1/15 of the apparent width of the moon.
This happened on March 4, 1226 – just a few months before the death of Francis of Assisi to give you an idea of the time frame. It was also the 20th year of Genghis Khan’s reign and one year before his death in 1227.
While 1226 was the last time an extremely close conjunction between Saturn and Jupiter was visible, it is not the last time this has occurred. In fact, conjunctions between Jupiter and Saturn occur every 19.6 years. Because of the angle at which Jupiter (1.3º) and Saturn (2.5º) both orbit the sun, when they meet every 19.6 years, they will be at different distances from each other, somewhere between 4º or less. Therefore, it is even rarer to see a conjunction smaller than 1 °.
In 2020 we will see one of the rare ones close to encounters, a tenth degree conjunction. To find a close connection comparable to the one in 2020, you have to go back to the 17th century in addition to 1227.
In the summer of 1623, Galileo enjoyed the telescope he had made 14 years earlier, in 1609. He did not know that there was a conjunction of planets taking place. Even if he had known, he wouldn’t have seen it. This planetary alignment occurred within 13 ° of the sun and was therefore not visible from Earth. Sad day for Galileo.
Now, in 2020, we will be seeing this spectacle in the coming weeks. If you look every night, you can see that the two planets are getting closer every night.
The “Great Conjunction” as it is called will eventually take place on the night of the winter solstice.
Right! Coincidentally, at the beginning of the longest night of the year, we will see two planets appear, separated by one-tenth of a degree (0.1 °). That’s about one fifth of the moon’s apparent diameter!
If you look through a telescope or even binoculars, you can probably see both Saturn and Jupiter in the same frame (already a rarity), as well as their moons!
Although these two gas giants ‘appear’ close together, they will of course still be hundreds of millions of miles apart. Jupiter is nearly 545 million miles from Earth and Saturn another 455 million miles beyond it.
Jupiter is the largest planet in our solar system and will shine the brightest. Saturn has a golden hue.
When these two planets “converge” on December 21, look at dusk and just after the sun sets. These two planets will also “set” pretty quickly and you don’t want to miss it! Look west.
Some have called this meeting the “Christmas Star” because the two planets together will appear so large and bright on December 21. I will note, however, that both astronomers and biblical scholars have determined that the star of Bethlehem could not be a conjunction between Jupiter and Saturn during the birth of Jesus, since a conjunction at that time would have been only about half a degree, or about the width of the moon, and therefore not so bright. Certainly not as bright as we will see on December 21. Also, remember that this event can happen any time of the year, not just December. It all depends on the 19.6 year cycle.
While this event will also take place in 2040 and 2060, it won’t be until March 15, 2080 before they are visibly that close again, or maybe even closer than we see in 2020.
If you see the poinsettia on December 21, send us your photos via the KOMU 8 Weather app!