Jupiter and Saturn will line up in the night sky on December 21, if astronomers call “great conjunction“- also called” Christmas Star “- marking the closest meeting of the planets in almost 400 years.
When Saturn and Jupiter converge on December 21, the two planets may appear as a bright spot of light that will be easily visible in the night sky. The two planets have slowly moved closer to each other in recent weeks.
A conjunction occurs when the planets appear incredibly close to each other in the sky because they align with the Earth in their respective orbits.
“You can imagine the solar system being a race track, with each of the planets as a runner on its own lane and the Earth toward the center of the stadium,” said Henry Throop, an astronomer in NASA’s Division of Planetary Sciences. said in a NASA statement. “From our point of view, we will be able to see Jupiter in the inner band, approaching Saturn all month and finally surpassing it on December 21.”
Related: Get ready for the “Great Conjunction” of Jupiter and Saturn
A rare alignment
While the orbits of Saturn and Jupiter bring the planets into alignment once every 20 years or so, this year marks the first time since 1623 that the two gas giants have passed so close to each other.
This year great conjunction it also marks the first time in nearly 800 years since the planets lined up at night and sky observers were able to witness the event. (The conjunction of 1623 was not visible to observers in the sky over much of the Earth because of its location in the night sky, so the last time the event was visible was in 1226.)
The planets will be closest to each other in the sky on December 21, appearing only at one tenth of a degree. They will remain closely aligned for a few days and will be easily visible to the naked eye when looking southwest immediately after sunset. While the two planets can be seen as a single point of light, they will remain hundreds of millions of miles in space, according to NASA.
Coincidentally, this year’s big conjunction also falls into first day of the winter in the northern hemisphere. As a result, some have referred to planetary alignment as forming a “Christmas star,” referring to the Star of Bethlehem, given that the event falls just a few days before Christmas.
“Such conjunctions could happen on any day of the year, depending on where the planets are in their orbit,” Throop said in a statement. “The date of the conjunction is determined by the positions of Jupiter, Saturn and Earth in their paths around the sun, while the date of the solstice is determined by the inclination of the Earth’s axis.
The solstice is the longest night of the year, so this rare coincidence will give people a great chance to go outside and see the solar system. “
As you can see
To see the astronomical event, sky observers should look at an unobstructed part of the southwestern sky, about an hour after sunset, as the planets will quickly settle below the horizon.
Until the conjunction of 21 December, Saturn it will appear slightly above and to the left of Jupiter. Then the planets will reverse their positions in the sky, NASA officials said in a statement.
Jupiter and Saturn are bright, so they can be seen in areas with clear skies and no clouds – and even in most cities. It also means that the event can be seen with the naked eye. However, binoculars or a small telescope can allow spectators to see The four great months of Jupiter, according to the statement.
Editor’s note: If you catch a stunning picture of the Great Conjunction of December 21 and want to share it with Space.com for a story or gallery, send pictures and comments to [email protected].
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