Winter solstice: Today is the biggest night of the year coinciding with rare astronomical phenomena

This year, the winter solstice will coincide for the first time with a very rare "coupling" of the planetary giants Jupiter and Saturn in the Earth's sky, as well as with the culmination of the last meteor shower of the year, the Ursid.

The night of the solstice, the first night of winter, as well as the next ones will be the longest of the year in duration. Conversely, summer will begin in the southern hemisphere, with the day at its peak.

When the Sun passes the winter solstice, it begins to rise higher and higher in the sky again, with the result that the day regains lost "ground", until at the vernal equinox light and darkness again have almost equal duration.

The winter solstice does not always "fall" on the same date, but ranges between the 20th and the 23rd of December, with the most probable dates being the 21st and the 22nd. These calendar fluctuations are due to the Gregorian Calendar.

The winter solstice no longer occurs on December 25, as in the time of Christ, but a little earlier, because the older Julian Calendar, introduced by Julius Caesar from 44 BC, has been replaced. This had established the winter solstice on December 25, but lost one day every 128 years. In 1582, Pope Gregory XIII introduced a new calendar, named after him (Gregorian), which loses only one day over 4,000 years.

The Sun was worshiped by the ancients as a god and almost all ancient peoples established various festivals in its honor, from the Scandinavians and Iranians to the Mayas and the Incas. Almost everywhere, the biggest celebrations took place during the winter solstice, which was considered the celebration of the birth of the Sun, which also marked the beginning of the new year. Prehistoric monuments such as Stonehenge in Britain are believed to have been associated with recording the movements of the Sun in the sky.

Central to the Romans was the celebration of the "invincible Sun" on December 25, when it was celebrated that the Sun began to rise in the sky again and thus the days grew longer. The first Christians in Rome, who secretly resorted to their catacombs, decided to celebrate the birth of Christ on the same date, December 25, when the Romans celebrated their own feasts of Saturnalia.

Rare celestial "coupling"

On December 21, the day of the winter solstice, the large planets Jupiter and Saturn will get so close to each other that they almost seem to touch and "kiss", resembling a double planet, according to NASA.

This spectacular astronomical phenomenon also called the "Great Coupling", is the first time it has happened in the earth's night sky in centuries. In fact, Saturn will be at least 730 million kilometers behind Jupiter, which will be 890 million kilometers from Earth.

According to Sky & Telescope, Saturn will be seen with binoculars or with naked eyes on the right of the brighter Jupiter, while four large satellites of Jupiter and at least one of Saturn, a total of seven celestial bodies, will also be visible with an amateur telescope in the southwest.

The approaches of the two planets - as seen from our planet - are relatively sparse, as they occur every 20 years or so. But this year's coupling is special because Jupiter and Saturn will seem to be coming so close. According to one estimate, the last time people could see something like this was in 1623, when Galileo was still alive, while the previous time was in 1226 in the Middle Ages. The rare "coupling" of the two large gas planets is due to their mismatched orbits. Jupiter, the largest planet in the solar system, takes almost 12 Earth years for a full orbit around the Sun, while Saturn takes almost 30. In addition, the two giants move in orbits with different inclinations around our parent star, which also makes it more difficult for them to pair up.

The two planets have been approaching each other in the Earth's sky since this summer and on December 21 they will be apparently separated by only one-fifth of the Moon's diameter. For about five days before and after December 21st, the two planets will appear to be as far apart as the diameter of the Moon. Those who prefer to wait will see a close coupling of Jupiter and Saturn again in March 2080, while this will not happen again until 2400.

Ursid meteor shower

At the same time, on the night of December 21st, the relatively light Ursid meteor shower will peak, the last "falling stars" of the year. The Ursid shower, which occurs between December 17-25 and produces five to ten meteors per hour, comes from dust left behind by Comet Tuttle, first discovered in 1790.

The diviners seem to come from the direction of the constellation Ursa Minor, hence their name. The sky will be dark enough to observe, as the next full moon will occur on December 30th.