Ted S. Warren / AP
If popular culture has taught us anything about the holidays, it’s time for reunions: a time when people can conquer great distances and long divisions to be together again. Usually, though, such stories involve cross-country trips – not the orbits of the two largest planets in our solar system.
This year will be different.
On December 21, Jupiter and Saturn – are actually separated More than 400 million miles – appear closer to each other in the night sky than they have been for centuries. Seen at the right time, through a telescope or with the naked eye, gas giants are separated by about one-fifth the diameter of a normal full moon. In this proximity, the planets touch or form a large, brilliant star in the sky.
The scenery is an interesting effect of their orbits. Since Jupiter takes less than 12 years to orbit the Sun and Saturn takes more than 29 years, the planets meet once every 20 years on Earth, which astronomers call the “great conjunction”. The last great conjunction occurred in May 2000, but at that time the average stargazer was likely to lose its position in the sky in the light of the sun.
Such a combination is so close and you have to go a long way to the past to find the last example it looks like to stargazers. Perth Observatory in Australia Said Jupiter and Saturn last consulted with each other in July 1623, but like the conjunction in 2000, it is very difficult to detect.
“You must return on the morning of March 4, 1226, to see the close alignment between these objects visible in the night sky.” Patrick Hortigan, An astronomer at Rice University, explained in a statement Last month.
Beyond the simple coincidence of timing, here is another holiday connection at work. Some astronomers, Dated by Johannes Kepler In the 17th century, that was reversed Star of Bethlehem What guided the three wise men to the birthplace of Jesus Christ in the Bible is like a set that will appear later this month – despite having different planets.
Saturn and Jupiter began to appear closer to each other this past summer, but this proximity scene is clearly visible in mid-December.
“Look low for them in the southwest hour after sunset. And on December 21st, the two largest planets will only appear one-tenth of a degree – it’s about the thickness of a dime at arm’s length!” NASA explained Earlier this month. “This means that both planets and their moons are visible in the same scene through binoculars or a small telescope. In fact, Saturn looks as close to Jupiter as some of Jupiter’s moons.”
After the winter, the two planets begin to separate again.
Now, this sentimental holiday reunion is not a Hallmark movie; If you missed it this year, don’t expect to see it again next December. Astronomers say that by 2080 there will not be another great conjunction near this.