Tonight Christmas Star Lights Up the December Sky for the First Time in 800 Years

When I think of the Christmas Star I think of two things. One the story of the three wise men in the Bible following the Christmas Star to the manger to honor Christ. The second is not so biblical. It's from "National Lampoon's Christmas Vacation" when Uncle Lewis says, "That's not the friggin' Christmas Star, Gris... It's the light at the sewerage treatment plant." See Chevy Chase and the rest of the cast couldn't have seen the Christmas Star because it hasn't been this bright in the December sky since the middle ages.

If there's one thing that I remember from my college astronomy class it's that the Christmas Star isn't a star at all. It's actually two planets that appear so close to each other that they are the brightest objects in the sky. That’s right, during the upcoming winter solstice, Jupiter and Saturn will line up to create what is known as the “Christmas Star” or “Star of Bethlehem.” An event that hasn't been seen in 800 years.

Alignments between these two planets are rather rare, occurring once every 20 years or so, but this time they will be really, really close together. Actually, they will just appear to us to be really close. In astronomical terms, they will actually be about 5 au's apart. An au is a measurement they use in astronomy called an Astronomical Unit it's the distance from the Earth to the Sun, about 92,000,000 miles. So, on December 21st during the winter solstice, Jupiter and Saturn will be about 460,000,000 miles apart.

We should turn our heads and telescopes to the southwest portion of the sky about 45 minutes after sunset to see the planets align on Dec. 21. However, you will be able to see the Christmas Star all week.

Wow, this is the first time I've actually used something from my college astronomy class. See my parents didn't just waste that college money on me.