For the first time in 800 years, people on Earth will be able to see the “Christmas star” in the night sky.
Astronomers call the phenomenon the “Great Conjunction” because it is when Jupiter and Saturn – the two biggest planets in the solar system – are close to Earth and to each other.
South Africans will be able to see the “Christmas star” on 21 December in the hours after sunset.
This December, South Africans will be able to see the rare “Christmas star” with their naked eyes. The last time the phenomenon was visible from Earth (1226 AD), the medieval Kingdom of Mapungubwe was still thriving in the north of South Africa and Europe was in the Dark Ages.
Although it is called the “Christmas star”, it is not actually a star shining brightly in the night sky. Astronomers refer to the celestial phenomenon as the “Great Conjunction”, says South African Astronomical Observatory astronomer Daniel Cunnama. It is when the solar system’s gas giants – Jupiter and Saturn – are close to Earth and each other.
Although the two planets align every 20 years, not all conjunctions are equal. “The last time they appeared this close was in 1623 AD, but they would have appeared very close to the Sun, and so very difficult for people to see,” he says. This year, like in 1226 AD, it is not near the Sun, so people can actually witness the Christmas star.
By chance, the conjunction also happens to coincide with the summer solstice – the longest day in the southern hemisphere, which occurs on 21 December. “The best time to see it is just after sunset,” says Cunnama. “If you look to the west, you’ll see two bright objects, two of the brightest things in the sky.” It is already possible to see them, he says, and over the next two weeks they will draw even closer together – although they will never actually overlap. “It is worth going out and having a look now.”
This year, the two planets are so close to Earth that you can see them with the naked eye. But Cunnama says that with a pair of binoculars or a small telescope, it is possible to observe the rings on Saturn and some of the moons that orbit Jupiter.
“It is really worth going out and looking at it for that reason alone,” says Cunnama. The next Great Conjunction will occur in 2080.
Source : Business Insider