Planets align as rare 'Christmas Star' appears in SA skies tonight

21 December 2020 - 06:00 By Toni Jaye Singer
According to NASA, the last time Earth had such a good view of a great conjunction of Jupiter and Saturn was in 1623.
According to NASA, the last time Earth had such a good view of a great conjunction of Jupiter and Saturn was in 1623.
Image: 123RF/Claudio Ventrella

Jupiter and Saturn, the two biggest planets in our solar system, are putting on a celestial show just in time for the holidays.

On December 21, which coincidentally is the summer solstice, these planets will align in a “great conjunction”, causing them to appear close together in the night sky.

They will look as if they're only about a fifth of the diameter of a full moon apart, says Dr Daniel Cunnama, science engagement astronomer at the SA Astronomical Observatory.

Though this astrological event occurs every 20 years, we don’t always get a good view of it from Earth. In fact, NASA states this is the “greatest great conjunction between Jupiter and Saturn” we can expect to see until 2080.

Media reports are calling the phenomenon a “rare double planet”, “Christmas Star” or the “Star of Bethlehem”.

These festive nicknames aren't technically correct because you'll be looking for two planets, not a single star, says Cunnama.

He says they likely stem from the work of Johannes Kepler, a noted 17th century German astronomer who argued that the Star of Bethlehem in the Bible story was actually the result of a great conjunction.

HOW BEST TO SEE THE GREAT CONJUNCTION

Look to the western horizon just after sunset and you'll be able to spot Jupiter and Saturn — the two brightest objects in the sky — in the same field of view, advises Cunnama.

These planets should be visible to the naked eye, but if you’d like a closer look and don’t have a telescope at hand, a pair of binoculars will do.

While not of huge astronomical significance, Cunnama says events like this great conjunction are wonderful because they “give everyone a chance to reconnect with the stars and planets and to look beyond Earth and all its troubles”.