By Phil Plait | December 21, 2006 2:22 pm

Today, December 21st, at 7:22 p.m. Eastern Standard Time, the Winter Solstice arrives.

What does this mean, exactly?

  • It is the longest night of the year, and therefore the shortest day.
  • If you were to trace the path of the Sun across the sky today, and note how high off the horizon the Sun was when it was due south, at the apex of its arc, then that point on the sky is the lowest it will be all year. In other words, tomorrow, the apex of that arc will be a tiny bit higher, and the next day it’ll be even higher, and so on. On June 21, 2007, the arc will be as high as it can be, and then it will inexorably start to drop again.

  • If you are in the southern hemisphere, then switch everything I’m saying here. Down is up, summer is winter, war is peace, and we have always been at war with Oceana (and I hear the chocolate rations are being increased).
  • The seasons are not caused by our distance from the Sun! In fact, we reach perigee perihelion (closest approach to the Sun) on January 3, 2007. If you are in the southern hemisphere, this may cause more confusion. That’s your own fault for living upside-down.
  • You still can balance an egg.

If you want more info on the solstice, try Sky and Telescope’s page, or the U.S. Naval Observatory’s FAQ page. And thanks to the Morehead Planetarium for letting me steal that image, even if they maybe don’t know I did so much.

CATEGORIZED UNDER: Astronomy, Cool stuff, Science, Time Sink

Comments (21)

  1. Cindy

    But Dec 7th was the day of the earliest sunset for those of us at latitude 40 North. And January 5th is the day of latest sunrise.

    A good explanation of this is at

  2. On June 20, 2008, the arc will be as high as it can be, and then it will inexorably start to drop again.

    Getting ahead of ourselves are we? What about June 20, 2007?

  3. Rob

    Happy Solstice from down under here in Australia. Fortunately chocolate is plentiful and down still appears to be down!

  4. Dangit, Janie, you’re not supposed to find my mistakes! Fixed.

  5. ABR

    I noticed that, too. I think skipping June 2007 is due to a last minute law passed by this Congress to outlaw the solstices next year (because of The War on The-War-on-Christmas, of course). Hopefully, the law will be scheduled to — ahem — sunset late next year.

    Oh…it was just a typo. Where’s the fun in that?

  6. Michael

    HA! Great Orwellian reference…

  7. I do read books other than texts sometimes…

    … and you mean “references.” I put in three. :-)

  8. Tim G

    Phil, do you mean “perihelion” instead of “perigee”?

    Barring the effects of cloud cover, I look forward to a sunnier day tomorrow.

  9. I hope everyone is preparing a proper sacrifice for the solstice. I’m going to be pissed if I wake up tomorrow to eternal darkness because some lazy SOB didn’t perform the necessary rituals to ensure that the God is reborn of the Goddess to bring forth the return of the Sun!

    Yeah, you talk all smart with your science and stuff, but you won’t be laughing after the world is plunged into eternal winter and darkness!

    OEJ ,-)

  10. Kristin

    Is anyone else bothered by that graphic? The two paths should be parallel, but instead it looks like the Sun will rise and set in the same place on the two solstices. For most of us in the Northern Hemisphere, the sun rises south of east (and sets south of west) now, and rises north of east (and sets north of west) 6 months from now.

  11. Sorry, Dr. BA. At least you didn’t get busted by the 17 year old fan-girl on the perigee/perihelion thing. Now THAT would have been embarrassing for an astronomer of your caliber.

    In my defense, however, let me just point out that Shakespeare was gnawing on my left arm at the time (he seems to have a thing for chewing only my left arm that I can’t explain), and Kate was attempting to um… otherwise distract me.

    Her technique is somewhat different from Shakespeare’s though.


  12. Phil,

    This is also the time of year when the full moon rises highest in the north. That 23 degree tilt makes for wonderful moonlight tracking in the snow. Unfortunately, this year it hasn’t even really been cold yet, and there’s not a snowflake in sight here in my part of Upstate New York.

  13. ThinCritter

    “UPSIDE DOWN”!!!, We’re not upside down, you’re upside down!!.

    Happy Solstice from down-under.


  14. Rob

    The Sydney Morning Herald has just posted a Reuters article about an artist creating a sculpture “Stellar Axis” comprising 99 blue fibreglass spheres on a 182 m diameter site in Antarctica on the solstice. The sculpture can only be set up for one day after which it has to be removed. No pictures yet though.

  15. So, is there a real Santa Claus on the South Pole?

    Yes, of course. He would be named SANTArctica.

    Then, he would bring toys to the children on June 25th.

    Of course Rudolph’s nose would have to be another color besides red, right?

    And, what color would that be…?

  16. On January 1 at 0200 the clocks go ahead a year. This “Daylight Savings Year” is being instituted by executive order to better service the ongoing conflicts in Iraq and Afghanistan.

  17. Seamyst

    Heeheeheehee… I almost snorted my OJ when I read your 1984 references, BA. Made my day.

  18. Oh nuts! TimG is right, and I corrected it. I’m making lots of dumb little errors like that lately. I have a lot on my mind, I guess.

  19. ioresult

    Phil said: “And thanks to the Morehead Planetarium for letting me steal that image, even if they maybe don√Ę‚ā¨‚ĄĘt know I did so much.”

    Oooh! You’re EVIL!!! hehehe

  20. “Of course Rudolph√Ę‚ā¨‚ĄĘs nose would have to be another color besides red, right?

    And, what color would that be√Ę‚ā¨¬¶? ”

    Green of course.

  21. Longest night of the year . . . and I’m observing tonight. . . all night . . .


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