Photo credit: Wikimedia
The 2011 December solstice occurs during the night tonight for us in the central United States, at 11:30 p.m. CST. That’s December 22, at 5:30 Universal Time. It’s when the sun on our sky’s dome reaches its farthest southward point for the year. After today, the sun’s path will begin climbing back northward again. For us in the Northern Hemisphere, days will begin to lengthen, as we move once more toward summer.
How do I translate Universal Time to my time?
Stonehenge marks winter solstice sunset GALLERY
At this 2011 December solstice, you can easily see several planets in the night sky. More about the planets below.
December 2011 guide to the five visible planets
But first … the solstice itself. At this solstice, we celebrate the (unofficial) first day of winter in the Northern Hemisphere and first day of summer in the Southern Hemisphere. Unofficial? Yes. Winter and summer start at the solstices by tradition, not official decree.
Yet these solstices bring very real occurrences to our sky, which you can witness for yourself. In both the Northern and the Southern Hemispheres, the December solstice brings the southernmost sunrise and the southernmost sunset of the year. If you stand in one spot day after day, week after week – for example, gazing out a window toward the sunset on the horizon – you will surely notice the sunset’s northward trek along the horizon over the coming months. From time to time, try fixing a bit of tape to the window on which you’ve written the date, to help you mark the sun’s passage.
In the Northern Hemisphere, the southernmost sunrise and sunset usher in the year’s shortest day and the longest night. In the Southern Hemisphere, it’s the exact opposite, for the year’s southernmost sunrise and sunset give the Southern Hemisphere its longest day and shortest night.
Not everyplace worldwide has a sunrise and a sunset on the day of the December solstice. North of the Arctic Circle – or north of 66.5 degrees north latitude – there is no sunrise or sunset today, because the sun stays beneath the horizon all day long. South of the Antarctic Circle – at 66.5 degrees south of the equator – you won’t see a sunrise or sunset either, because the sun stays above the horizon all day.
Jupiter in the south and Venus in the southwest at nightfall
Want more? Everything you need to know: winter solstice
Planets visible at 2011 December solstice. To celebrate the winter solstice, try looking at the blazing planets Venus and Jupiter at nightfall. Although the solstice occurs on or near December 21 every year, the planets’ positions in the starry heavens are not fixed. For instance, Jupiter now lodges at the border of the constellations Pisces and Aries. One year from now – on the 2012 December solstice – Jupiter will be in front of the constellation Taurus the Bull, near the star Aldebaran.
If you’re up early tomorrow, on Thursday, December 22, you might witness another event that’s special to this year’s December solstice: the pairing of the moon and the planet Mercury in the predawn and dawn sky. Look in the southeast around 90 to 60 minutes before sunrise, as displayed on the chart at left. In fact, the next few weeks will present a particularly favorable time for catching Mercury in the morning sky.
After the sun reaches its southernmost point on the sky’s dome on the December solstice, watch as the sun seems to pause for a number of days before it starts its northward trajectory on the sky’s dome once again.
By the way, the image at the top of this post shows the 2004 winter solstice viewed at the Lawrence Hall of Science in Berkeley, California, USA.
Botton line: In 2011, the December solstice comes on December 21 at 11:30 p.m. CST. That’s December 22 at 5:30 UTC. It’s when the sun on our sky’s dome reaches its farthest southward point for the year. At this solstice, you can easily see Jupiter and Venus in the evening sky. You can also see Mercury near the moon before dawn.
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I was wondering why today –Dec 21 winter solstice– isn’t the coldest day of the year in the northern hemisphere. So I read about this “Seasonal Delay” phenomenon, where the coldest day of the year is not generally close to the shortest day, but comes a couple of weeks to a month later. Our coldest months in northern latitudes are December, January, and February, even though the winter solstice is in December. So there is a delay, or lag between the shortest day (the day with the least amount of sunlight during the year) and the coldest time of the year. The same situation happens with June 21 (the summer solstice), which is the longest, but not the hottest day of the year.
For the winter solstice, the reason for this delay between maximum cooling and maximum cold (temperature) is that heat stored in the ground gradually leaks out, giving us our coldest weather in January and not in December, when the shortest day occurs.
For the summer solstice, the reason for this delay between maximum heating and maximum heat (temperature) is that it takes time to warm up the ground thus the hottest days come in July, not in June, for the northern hemisphere, that is, about a month’s delay from the onset of summer –the longest day of the year–.
I read all this in an Iowa State University online article titled “Seasonal Delay” because I was wondering why TODAY isn’t at all the coldest day of the year, for northern hemisphere inhabitants and got a very clear answer to my question, so I wanted to share with you all!
while it takes time 4 the ground 2 heat up and cool off, a large portion of this delay also is due to the same phenomenon occurring with the air itself and ocean especially) and fresh water bodies (particularly any water near the surface, both salty and fresh). it’s kinda like if u imagine turning a burner with cold water in it up to medium heat for 2 minutes, then high heat for 2, then back to medium heat for 2 more. Obviously the water will b warmer the second time it is on medium heat (equivalent to the fall equinox) rather than the 1st time (equivalent to the spring equinox). And the water, assuming it doesn’t boil, will be warmest after the midpoint of its high heating (equivalent of the summer solstice). Like wise when the heat is turned off, it will cool off in a manner such that even if the heat were turned back on, the minimum temperature would b right be4 the heat was turned back on (or even after if the heating is very small and the water is still radiating a lot of heat to the surroundings), rather than at the middle point of no heat (equivalent to the winter solstice). hope that made sense.
Yeah, proximity of water is definitely the other part of the equation. Water is much better at storing energy than dry soil. So, if you are surrounded by water, as some island-like countries are, then the water stores energy from the summer and releases it throughout the winter, which keeps things warmer (and delays the minimum temperature in the winter as well).
And the last part of the equation are HUGE air masses coming from the arctic (which may gradually COOL DOWN the temperature of a given city, delaying or completely eliminating the heating of the place during summer), or HUGE currents of warm water coming from a nearby ocean on the contrary, may delay or even completely eliminate the cooling down of a place in winter.
Some places even have both things (cool air from the arctic and the warm air from the ocean) colliding against each other, therefore creating a very variable weather!