In a few days, our solar system's two biggest planets - Jupiter and Saturn - will come within close proximity of one another in what is known as a great conjunction, a rare event that may resemble the biblical Star of Bethlehem, also known as the Christmas Star, according to the US National Aeronautics and Space Administration (NASA).
The term "conjunction" in astronomy is used to refer to the meeting point of celestial objects in space. A great conjunction refers to the rare moments in our solar system's history when its two largest planets have come close together.
“You can imagine the solar system to be a racetrack, with each of the planets as a runner in their own lane and the Earth toward the center of the stadium,” said Henry Throop, astronomer in the Planetary Science Division at NASA Headquarters in Washington, according to the NASA website. “From our vantage point, we’ll be able to be to see Jupiter on the inside lane, approaching Saturn all month and finally overtaking it on December 21.”
Jupiter and Saturn have been traveling together all year. But over the first three weeks of December, they have gradually come closer together. This form of celestial teasing will culminate on Monday, December 21, when it might seem like the two planets have completely integrated into one massive star.
"This rare astronomical event, known as the great conjunction, only appears every 20 years," NASA Headquarters guide Tahira Allen explained, according to the space agency. "However, the last time they've been seen this close was in 1623."
And that's not all. This year's great conjunction will be the closest observable one since 1226, according to EarthSky news website.
Witnessing the closest connection between Saturn and Jupiter seen in nearly 800 years is guaranteed to be a spectacular event – and will not even require a professional telescope. In fact, the two huge planets will be so close together, and close enough to Earth, that the cosmic event will be viewable with the naked eye in clear weather conditions.
Jupiter and Saturn are both considered extremely bright, with Jupiter being "brighter than any star" and Saturn shining with a "distinctly golden color," EarthSky noted. Saturn has even been referred to as the "jewel of the Solar System." But, unlike stars, the meeting point between Jupiter and Saturn will not appear to be twinkling. Instead, it will shine steadily.
Over the years, theologists and enthusiasts alike have speculated that the Biblical Star of Bethlehem that appears in the nativity story of the Gospel of Matthew was actually an instance of a great conjunction between Jupiter and Saturn in disguise. In the story, the bright star guided "wise men from the East" to baby Jesus in Bethlehem.
However, there are quite a bit of reservations to this theory. For starters, no one has actually seen a great conjunction like this one in 800 years, and there's no guarantee that the two planets will appear to overlap. As Jupiter is brighter, some astronomers believe you will be able to distinguish the individual planets with the naked eye.
Bible experts are also divided, according to the UK Express website. The Reverend Dr. M.W. Burke-Gaffney wrote in the Journal of the Royal Astronomical Society of Canada that "no matter how close together two planets come – even if one planet should be so close to another as to partly obscure it – Wise Men would not mistake them for a single star. A few nights' watching would show them separating – as they would have also been seen to come together."
In any case, this is the greatest great conjunction between the two giants for the next 60 years. They will not appear so close in the sky until the year 2080. So whether you believe it made a guest appearance in the Bible a couple of thousand years ago or not – it's an event worth marking in your calendars.