# What is Christmas: Definition and 140 Discussions

Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration by billions of people around the world. A feast central to the Christian liturgical year, it is preceded by the season of Advent or the Nativity Fast and initiates the season of Christmastide, which historically in the West lasts twelve days and culminates on Twelfth Night. Christmas Day is a public holiday in many of the world's nations, is celebrated religiously by a majority of Christians, as well as culturally by many non-Christians, and forms an integral part of the holiday season organized around it.

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1. ### Christmas Presents: What Did Santa Bring You?

Alright guys, spill the tea... what'dya get? Santa gave me a neat little periodic table paperweight-thing with some samples inside. 😄 Happy Christmas!
2. ### B Happy Christmas: Is it Really True?

Is this really true? It resembles the binomial theorem. I've posted it twice which might be breaking rules. Happy Christmas PF.
3. ### Are you ready to celebrate with fellow PF members this Christmas?

Merry Christmas PF members! Thanks everyone for another interesting and fun year! And thanks to @Greg Bernhardt for keeping the forum alive! (especially during these trying times we have lived, and are living, with the corona virus)
4. ### MHB Burning time of Christmas Tree

Hey! :giggle: The burning time of an electric candle is between $60$ and $80$ hours. It is considered to be continuously uniformly distributed over this period. A Christmas tree with $12$ candles (independent of the burning time), only lights up as long as all candles are working. Determine...
5. ### I Observing Christmas Lights in a Black Hole: What You See

If a string of blinking Christmas lights extends from the center of a black hole out to a large radius r. What do I see, if I am perpendicular to the line of lights, at radius r? Experiment specifics 3 solar mass, non-charged, non spinning black hole. Observer is 1,000 Au from the center of...
6. ### Got the new Microsoft Flight Sim for Christmas

It was a gift from my daughter and her boyfriend. I had the older Flight Simulator X, and the timing of the release of this new version coincided with my getting a new computer. I'll have to say that I am impressed. Even though I'm not running the graphics at the full realism setting, I was...
7. ### Merry Christmas 2020 | Wishes to All

Merry Christmas to all!

45. ### A Christmas tree ball hangs from a hook in the ceiling.

Homework Statement A Christmas tree ball hangs from a hook in the ceiling. If the radius of the ball is 8 cm, find the period of the ball's oscillation as it swings on the hook. Homework Equations T=2pi*√L/g The Attempt at a Solution I tried pluggin the number and I'm way off...
46. ### Christmas Tree Light: Investigating the Math Behind Its Curve

Forgive the sloppy use of math and inability to produce an image. I noticed this last christmas. If you have a fairy light ( or perhaps any LED etc), and shine it normal to a surface, you see a circle. If you place the light flat on the surface you see a curve - to me the fairy lights' curve...
47. ### Are You Ready to Become an Astrophysicist with Your New Telescope?

You should have seen my face when I tore open one of my christmas presents this year. I got a MEADE ETX-80 Refracting Telescope. Last night the sky was a bit cloudy, thus we could not see any stars, or the moon, thus we couldn't use the telescope. But tonight it was a perfect night. Me and my...
48. ### What did you get for Christmas this year?

What did you or your significant other get for Xmas this year? Anything surprising, anything unexpected or over-the-top or just totally unexpected? My wife got fuzzy sandals from her sister that make her look like the Energizer Bunny, but she wore them last night. Duke got a tug-toy that...
49. ### Christmas season temporary jobs

Tis almost the season when all of the folks hired temporarily for the Christmas season get tossed out on the streets, to wander aimlessly about until they find the unemployment line. I wonder what it must be like to be a Christmas season temporary employee. Finally, someone has captured the...
50. D

### What Are the Best Science Books to Get for Christmas?

Hello, I'm new to these forums and not 100% sure of where this type of thread would go. I have decided that this year, for Christmas, I would be getting a bunch of books on science :cool:. I got up to \$200 dollars to spend, including shipping, and want to know if there are any books that...