HUNTSVILLE, Ala. — One the night of December 21st, folks across the Tennessee Valley will be able to step outside and witness something that hasn't been seen in nearly 800 years.
This isn't an event that happens once every 800 years, but it is an event that hasn't happened this perfectly in about 800 years.
Jupiter and Saturn appear to pass each other in their respective orbits once every 20 years according to NASA. Jupiter takes about 12 years to orbit the sun while Saturn takes 29.5 years to orbit the sun. Every 20 years, Jupiter catches up to and appears to pass Saturn.
The reason this event is called a "Great Conjunction" is because Jupiter and Saturn move very slow, so they almost never appear to align or pass each other. Again, this only happens once every 20 years.
The thing about this year is that it has been 400 years since the planets have passed each other while appearing so close to each other. It has been 800 years since this event occurred at night making it visible for everyone.
According to Space.com, the next time this event happens exactly as it will on Monday December 21st. is July 6, 2477.
For the best viewing, it is suggested that you go outside just after sunset and look towards the SW. A viewing aide will not be necessary, though if you use one, you should be able to view the moons of Jupiter.
The fact that this event is happening on the winter Solstice is a pure coincidence. What will be the incredibly bright spot in the sky is being referred to as the "Christmas Star" given how close we are to Christmas.