- Jupiter and Saturn will align in the night sky on Monday. It will be the closest to appear in 800 years.
- The two planets move into alignment, or conjugation, every 20 years. But this year they will be so close that they will look like “double planets”.
- The last time both Saturn and Jupiter were close and the scene was in 1226.
- Here are the best ways to view or view live streams, photos of a combination.
- For more stories visit the Business Insider homepage.
Jupiter and Saturn, about to line up in the night sky, are getting so close on Monday that they will begin to touch.
The last time they were seen was about 800 years before Earth’s vantage point, on 4 March 1226.
An astronomical event in which the celestial bodies align is called conjugation. Since this combination includes the two largest gas giants in our solar system, it is known as the great combination. It happens once every two decades.
“But it is fair to say that this combination is really extraordinary in that the planets get very close to each other,” said Patrick Hartigan, professor of physics and astronomy at Rice University.
“In fact, they will be so close that for many people it can be a challenge to tear them apart with no eyes,” he said.
How to see this rare coincidence on Monday night.
How to watch ‘double planet’
Jupiter and Saturn are actually more than four times the distance between the Earth and the Sun.
But on Monday, the night of the winter solstice, they would, according to Hurtigan, separate into the sky in a distance equal to about one-fifth of the diameter of the full moon. It is so close that two points of light will look as if they form a double planet. According to NASA, a pink finger at arm’s length should easily cover both Jupiter and Saturn in the sky.
According to NASA, this “Christmas Star”, as it is nicknamed in combination, should appear brighter than almost every star in the sky.
Viewed through a small telescope, Jupiter and Saturn must appear in the same region with some of their moons.
For audiences in the United States, Canada and Europe, this combination can be challenging to watch because of how low it will be on the horizon in the Northern Hemisphere, Hartigan said.
“The viewing position is closest to the equator, although no matter whether you’re there or not, the coincidence is about an hour or so to be immersed in planetary fog before observing,” he said.
To get a glimpse, exit after twilight – the hour after sunset – and point your telescope towards the southwest sky. (Websites like Stellarium can help you orient your telescope.)
“You won’t need to have a clear southwest horizon and no less clouds in the distance,” Hartigan said.
He recommends setting up your telescope before it becomes dark and bringing binoculars, which may also put you on Jupiter’s four moons.
If it ends up where you live on Mondays, don’t worry, Hartigan said. The conjunction is an ongoing event that lasts until December 25 – Monday is just when the two planets will be closest in the sky.
Henry Throop, a NASA astronomer, said in a press release, “You can imagine a run of the solar system, with each planet in its own lane as a runner and towards the Earth Stadium.” “From our vantage point, we will be able to see Jupiter on the inside lane, reach Saturn for the entire month and eventually overtake it on December 21.”
You can take pictures in conjunction with your phone
NASA said that the combination of Jupiter and Saturn “can be easily photographed on DSLR cameras and many cell phone cameras.”
The agency suggests using the “Night Mode” feature on the iPhone, Pixel, or Galaxy to get a stable, prolonged exposure photo.
NASA said, “Try to cover the planets with something – the silhouette of a tree, an outdoor landscape, an arch of a building or even a neon sign.”
If you use a DSLR camera, a tripod is recommended to get good long-exposure photos. In the absence of a tripod, set your camera to a shutter speed of less than a quarter of a second. NASA said make sure to open your camera’s aperture in its wider settings and also use manual focus mode.
For those who cannot opt out for this event, the Lowell Observatory in Flagstaff, Arizona, will host a YouTube livestream of views via its telescope starting at 7 pm ET on Monday. In Rome, the Virtual Telescope Project also plans to share live views of the combination.
Another such combination will come in 2080
In the last 2,000 years, only twice has it happened that Jupiter and Saturn have come close to the sky, as they will achieve this year. One was in 1623, but the glare of the sun made it impossible to see. The other was in 1226.
But if you miss the Constitution on December 21, another 60 years will come.
On March 15, 2080, Jupiter and Saturn will appear around this month. The event will be easy to see, as it will appear high above the horizon, Hartigan said.
“Big challenge,” he said, “you have to live for another 60 years to see it!”