We are approaching an amazing close conjunction of Jupiter and Saturn on Dec 21. This will be the closest well-placed conjunction since 1226. The weather prognosticators are forecasting some cloudy and showery weather in the coming days and nights. Don’t lose hope.
Saturn and Jupiter were about 1 ½ degrees apart onDec. 7. In the Umpqua Valley, the great conjunction will be visible on the evening of Dec. 21 with the minimum separation of 6 arc minutes and 20 arcseconds between 4:30-4:45 p.m.
Officially, the minimum separation is 6 arcminutes at 10:20 a.m. How small is 6 arcminutes? If you gaze at the waxing moon with your unaided eyes, you can spot a dark oval near the top right of the moon. That’s the Sea of Crises and it appears about 6 arcminutes across.
Observers looking with unaided eyes will not notice the 2 or 3 arcminute difference from Dec. 20-22. Observers using binoculars or a telescope will be able to detect the apparent movements of Jupiter relative to Saturn. On Dec. 20, Jupiter will appear almost directly beneath Saturn. The next night, Jupiter will be below and slightly to the left of Saturn.
Looking on Dec. 22, Jupiter is now directly left of Saturn. Only on Dec. 23 will the two planets be clearly visible with your unaided eye with a separation of 16 arcminutes. Seeing Jupiter and Saturn appearing to nearly touch this close, as seen on Dec. 23, has only happened one other time in the last 200 years.
By Christmas night, Jupiter will appear to have moved nearly a moon-width away from Saturn. Although the separation is about 30 arcminutes, only three times in the last 200 years has that occurred.
Weather conditions in December can make stargazing difficult. Cloudy nights are now common. However, to see the conjunction, you will only need a small break in the clouds near the southwest horizon for a few minutes around 5 p.m. No matter what the forecast indicates as an overall pattern, being prepared, being patient and persevering can obtain a short opportunity to see the conjunction.
Also, you can look for several nights from Dec. 20 to Christmas night to see a wonderful celestial event. Don’t be fixating on Dec. 21 as your only chance. Check out every night and cross your fingers for a lucky break.
Okay, but what can I do if the clouds won’t part on Dec. 21? If the clouds win, you can seek images of the minimum separation online. The Virtual Telescope Project in Italy is hosting a great conjunction viewing starting at 8 a.m. on Dec. 21. Go to www.virtualtelescope.eu/webtv.
You may also try the Astronomy Magazine website at 4 p.m. at astronomy.com/news/sky-events/2020/12/jupiter-and-saturn-will-form-rare-christmas-star-on-winter-solstice to watch the conjunction.
Remember this is a multiple night event well worth attempts any night from Dec. 20-25. Good luck and good observing.