Rare ‘Christmas Star’ to be visible tonight
Today also marks the summer soltice, the longest day in the southern hemisphere
There will be a great conjunction of Jupiter and Saturn on 21 December
The year 2020 will go down in history as quite gloomy. But, it also brings a “bright star”. There will be a great conjunction of Jupiter and Saturn on Monday 21 December.
These occur about once every 20 years or so, but are often not visible as they can occur during the day.
According to the Hayden Planetarium in New York, one was recorded in 1623, but that conjunction was not very visible from Earth.
One has to go back further, to 1226, according to Virginia Tech astronomer Nahum Arav, to have seen the two this close together.
The next time that they will appear to be this close together is in 2080. A great opportunity for grandparents to show their grandchildren – and when they in turn see it again, they can tell their grandchildren that they saw it 60 years before!
For us in South Africa the spectacle happens after sunset at around 20:00 when the pair will be about 20 degrees above the western horizon, with a separation of 6′ (arc minutes), or about a tenth of a degree.
With the planets this close, they can be seen in a low power telescopic or a pair of binoculars. Jupiter’s disk will be twice as big as that of Saturn’s but its rings will appear larger than Jupiter’s diameter.
This will be a spectacular sight with the naked eye or binoculars.
It is of course also the longest day of the year, but not the time of earliest sunrise and latest sunset, which occur on 6 December and 7 January respectively. The reason for this is that Earth does not travel at a constant speed around the Sun since its orbit is an ellipse. Our watches run according to an “averaged-out” time, so there will be a slight difference between sun-time and watch-time! The difference is known as the “Equation of Time” and can be as much as 16 minutes.
These two events are good enough reason for us to celebrate the festive season, at home with our families and a bottle of bubbles, and may 2021 be a better year!
This article was republished from Mosselbay Advertiser with permission
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