The earth is presently hurtling towards that instant in time when its axis points most directly away from the sun (for the axis "protruding" out of earth's north pole, in the northern hemisphere) and most directly towards the sun (for the axis "protruding" out of earth's south pole, in the southern hemisphere) -- that is to say, the moment of the December solstice.

For those in the northern hemisphere, this moment is the winter solstice, although it is the summer solstice for the southern hemisphere.

Previous posts discussing the solstices compared the earth to a sailing ship of old: if the north pole is the spar protruding from the bow of the ship, and the south pole is the lantern at the stern of the ship, then the December solstice is that moment in which the lantern points directly at the sun as the ship circles the sun (in this metaphor, the "ship" stays pointed in the same direction, even as it orbits the sun).  For diagrams see this previous post.  

For other posts discussing the mechanics of the solstices and equinoxes, see also "Winter Solstice 2011," "Important cross-quarter day approaching!" "Summer Solstice 2013," and "The Hobbit and Summer Solstice," among others.

Also, this excellent post from Deborah Byrd at EarthSky gives some good discussion of the mechanics of the solstices, as well as pinpointing the time that earth will pass through the December solstice this year: at 17:11 Greenwich Mean Time tomorrow (21 December), which will be 9:11 am the same day (21 December) for North America's Pacific coast (at least for those on California time).

For observers in the northern hemisphere, the December solstice is that point at which the sun's arc finally ceases its downward (southward) motion.  It has been rising further and further south (along the eastern horizon), and arcing across the sky at a lower and lower angle (closer and closer to the southern horizon) ever since it passed the point of the June (summer) solstice.  Now it ceases that "descending" motion and begins to ascend again -- back towards the summit of the summer solstice.

The ancient Egyptians symbolized this point of the sun's commencing its northward-upward journey with profound allegorical imagery.  The Sun embodied the life-giving principle, and its commencement of the return back towards the north and the plant-growing time of the year was described as the rising of the mummified god Osiris.  The line between the lowest point on the zodiac wheel (the winter solstice) and the highest point (the summer solstice) was like a pillar in their symbology -- and that pillar was described as the backbone of Osiris, the life-giving backbone which supported the whole world and in fact supports the whole universe.  

For diagrams of the wheel of the zodiac, see for instance the circular zodiacs shown in this previous post. Those zodiac wheels are discussing the ages-long "movement" of the solstice points through the different houses of the zodiac, which is a function of precession, but if you draw a vertical line from the lowest point on those wheels (at the line between the signs of Sagittarius the Archer and Capricorn the Goat, extending upward to the line between the signs of Gemini the Twins and Cancer the Crab, which looks more like a Lobster on those particular zodiac wheels) then you will have an idea of the ancient "pillar" which the ancient Egyptians described as the "backbone of Osiris."

This pillar, a pillar of great importance -- a life-giving pillar -- was called the Djed column by the Egyptians.  Some early Egyptian scholars spelled it the "Tet" column or the "Tat" column, although they usually placed a small dot under both "t"s in the word, to show that they should be "voiced" (so that it would sound more like "Djed").

In Ancient Egypt the Light of the World, the insightful nineteenth-century scholar, thinker, and elucidator of the mysteries of ancient Egypt, Gerald Massey, says this of the Djed column:
[. . .] the tat pillar [. . .] was founded in the winter solstice as the figure of a stability that was to be eternal.  In the mythos the tat is a type of the sun in the winter solstice that has the power of returning from the lowest depth and thus completing the eternal road.  In the eschatology it is the god in person as Ptah-Sekeri or Osiris, the backbone and support of the universe.  Horus erecting the tat in Sekhem was raising Osiris from the sepulchre, the father re-erected as the son in the typical resurrection and continuity of the human spirit in the after life.  190.
The image above shows the Djed column, with its stylized "backbone" shape, surmounted by two arms (which often represent the ka), and an Ankh, the cross of life.  In this particular image, which comes from the Papyrus of Ani, which contains texts from the Egyptian Book of the Dead, the arms are holding up the Sun, and thus the symbology of the Djed pillar, the Ankh of life, and the now-ascending life-giving Sun all work together to convey the concepts discussed above and tend to validate the assertions of Gerald Massey regarding the backbone of Osiris and the winter solstice.

These are important things to understand and to contemplate on this December solstice, 2013.