Jupiter and Saturn form the Christmas Star on the winter solstice, the first “double planet” to appear in 800 years

By the end of 2020, Jupiter and Saturn will be so close that they appear to be a “double planet.” This amazingly well-connected combination, as the planet’s alignment is known, did not happen in nearly 800 years.

When their orbits align every 20 years, Jupiter and Saturn get very close to each other. Jupiter orbits the sun every 12 years, while Saturn’s orbit takes 30 years, so every few decades Jupiter loses Saturn, according to NASA.

The great 2020 correlation is particularly rare – the planets were less close together in nearly 400 years, and have not been seen so close to night since the Middle Ages, in 1226.

“Alignment between these two planets is very rare, happening once every 20 years or so, but this connection is very rare due to the proximity of the planets to each other. , “Rice University astronaut Patrick Hartigan said in a statement.” You had to go all the way back just before the morning of March 4, 1226, to see a closer alignment between these objects seen in the night sky. “

What makes a good relationship?

In 1610, the Italian astronomer Galileo Galilei discovered both the four branches of Jupiter – Io, Europa, Ganymede, and Callisto – and Saturn’s rings. Shortly afterwards, in 1623, the two planets were first seen to be aligned.

The connection is sometimes referred to as the “Christmas Star” or the “Star of Bethlehem” for its connection to the story of Christian nature. In the story, the star leads the wise men to the home of Jesus, which many Christians believe was a miracle. Astronomers have tried to associate the star with a number of rare celestial events – including a comet, a supernova and an association.

Aligning with the winter solstice on December 21, 2020, the two planets will be just 0.1 degrees apart – less than the diameter of a full moon, EarthSky said. The word “connection” is used by astronomers to describe the meeting of objects in our night sky, and the great connection occurs between the two largest planets in the solar system. We: Jupiter and Saturn.

The planets are so dense, they appear, from some perspectives, in full interference, creating the effect of a rare “double planet”. So close, that “a pinkie arm at arm ‘s length easily covers both planets in the sky,” NASA said.

However, while they may appear from Earth to be very, very close, in reality, they are still hundreds of millions of miles apart.

Jupiter and Saturn will come within 0.1 degree of each other on December 21, 2020, during what is known as the “great connection.”

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How to watch the big link

During the last major connection in 2000, Jupiter and Saturn were so close to the sun that it was difficult to see the event. But skiers should have a clearer view of the celestial event this time around. The giant conglomerate shines shortly after sunset, low in the southwestern skies, as seen from the Northern hemisphere, NASA said.

Throughout December, astronomers will find it easy to see both planets with the naked eye. You can look up every evening to see them coming closer and closer in the sky – they are so bright, they are even visible from most cities.

Jupiter is currently appearing brighter than any star in the sky. Saturn is slightly lower, but still as bright as the brightest stars, with a recognizable yellow glow.

Saturn will appear just above and to the left of Jupiter, and will even show as close to the planet as some of its own branches, visible with a telescope or telescope. Unlike connecting stars, the two planets maintain a constant, easy-to-find brightness on clear nights.

“You can imagine the solar system as a racetrack, with each of the planets as a runner in their own series and the Earth towards the center of the stadium,” said Henry Throop, astronomer there the Department of Planning Science at NASA Headquarters. “From our vantage point, we will be able to see Jupiter on the inner row, approaching Saturn all month and finally passing through December 21.”

The event is visible from anywhere on Earth, as long as the sky is clear. “The farther north an observer is, the less time they have to see the connection before the planets will sink under the horizon,” Hartigan said.

The planets appear very close for about a month, giving viewers plenty of time to observe their amazing alignment through the holiday season. The event coincides with the December solstice, marking the shortest day of the year in the northern hemisphere.

“Such sympathies can occur on any day of the year, depending on where the planets are in their orbits,” Throop said. , and the Earth in their orbits around the Sun, while the date of the solstice is determined by the tilt of the Earth’s axis. The solstice is the longest night of the year. , so this rare mutual understanding will give people a good opportunity to go out and see the solar system. “

To learn more about when and where to look for the connection, Throop will be live on NASA ‘s website to answer questions Thursday afternoon.

This is the biggest “biggest” connection for the next 60 years, to 2080. Hartigan said that, after that connection, the two will not take such a close approach until sometime after the year 2400.